Magnetic field sensor

 

Usage: in a semiconductor magnetic field sensors. The inventive magnetic field sensor includes a semiconductor sensor with an active area in which during operation a signal is generated in response to a magnetic field. The semiconductor element is at least partially, in the mode of pure conduction in the absence of bias, and at normal operating temperature. The element contains a transition that is shifting to reduce pure conduction in the active region and the limitations of the charge carriers predominantly only one type in accordance with saturated impurity mode and includes means for detecting the signal generated in the active region in response to the applied magnetic field. The technical result of the invention is to improve the measurement accuracy due to the fact that the sensitivity to the measurement of the magnetic field essentially does not depend on the temperature sensor. 2 N. and 25 C.p. f-crystals, 16 ill., 3 table.

This invention relates to the magnetic field sensor of a semiconductor material.

Before discussing the prior art will be discussed polyproteins, and, generally speaking, there are three critical conduction mode: unsaturated impurity, saturated doped and pure (native), and they are at low, medium and high temperature respectively. In the unsaturated impurity mode current thermal energy is insufficient to ionize all of the impurities, and the carrier concentration depends on temperature due to the fact that with increasing temperature ionize more impurities. The media must be activated from the dopants of the same species, donors or acceptors. The conductivity is essentially due to one type of media in the same area, i.e., electrons in the conduction band or holes in the valence band, but not both. Saturated impurity mode is similar, but occurs at higher temperatures, when virtually all impurities become ionized, but insufficient thermal energy is suitable for ionization of a significant number of States of the valence band to create electron-hole pairs: here, the carrier concentration mainly depends on the temperature.

In pure mode in conductivity makes a significant contribution to thermal ionization States of the valence band, giving both types novtel the ity is due to both types of media in both zones, i.e., electrons in the conduction band and holes in the valence band. The conductivity varies with temperature in this mode, because the concentration of electron-hole pairs depends on the temperature. There is an intermediate zone of transition between modes of doped and pure conduction, where the conductivity is partly impurity and is partly of their own, which leads to an increase in the number of charged carriers of one type over another, i.e. are the majority carriers and minority carriers, as it happens, for example, in Ge at ambient temperature or close to it, depending on the doping. The initial temperature for the impurity of the conductivity depends on the width of the energy gap and the concentration of dopant; it may be below ambient temperature up to 150K for narrow-gap semiconductors with a low dopant.

Materials such as Si and GaAS with saturated impurity regime at room temperature are preferred for use in the magnetic field sensor, in spite of the worst properties of mobility, due to the fact that the Hall effect or resistance basically should not depend on temperature. On a at ambient temperature, weakly doped Si is sometimes considered to be pure falsely, as it takes place in controlled resistive diodes (PIN diodes), where I is the region with high resistivity (“pure”) is actually at ambient temperature impurity region. The clean Si available at the present time, has impurities on the order more than you want to be pure when the ambient temperature.

The magnetic field sensors using semiconductor materials, has been known for many years. They include:

(a) magneto-resistive sensors, which change electrical resistance in response to the applied magnetic field, and

(b) sensors based on the Hall effect, the response to the magnetic field is the emergence of a voltage proportional to the current sensor and the field strength.

The electrical resistance RMmagneto-resistive sensor with impurity semiconductor in a magnetic field is given by the formula

where- the mobility of charge carriers and R0- the resistance of the sensor in the absence of a magnetic field.

Magneto-resistive contribution in equation (1) is

where Ey- electric field (intensity), the resulting Hall effect;

ty- the size of the semiconductor thickness, in the direction which is measured VH;

n is the concentration of charge carriers;

e is the charge on each charge carrier (negative for electrons and positive for holes);

jxthe current density in the semiconductor per unit cross-sectional area;

Inz- magnetic field; and

the indices x, y, z represent coordinate axes x, y and z and the direction of the parameters to which they are added.

For impurity mode with one type of charge carriers, the Hall coefficient RHis defined as

The situation is more complex than the equation (3), if the semiconductor is in pure mode with two types of charge carriers.

The conductivity of the materialis defined by the formula

=ne< the charge carriersHdefined as the hall mobility can be obtained by multiplying equations (3) and (4), i.e.

H=RH(5)

If the conductivity is doped, the hall mobility is different from the mobility at the expense of conductivity on the numerical value, which depends on the scattering mechanism (relaxation) media. However, the hall mobility and mobility at the expense of conductivity follow the same General principles will be considered equal and denoted as. If the conductivity is pure (native), the expression for the Hall coefficient is more complex and depends on the magnetic field.

For ease of measurement requires significant the Hall voltage. It can be achieved by using a high current density, which requires a low resistivity to limit the dissipation of energy and, consequently, high carrier mobility. Also for magneto-resistive sensors are required to have a high mobility of carriers to reduce the resistance and, therefore, energy costs and to increase the sensitivity of a magneto-resistive sensor OTNOShENIYa (1). Narrow-gap semiconductors, such as InSb or InAs that best satisfy this criterion of mobility. InSb has e-mobilitye=8 m2/with approximately ten times greater than that of GaAs, for which mobility is 0.85 m2/that, in turn, is better than the mobility of the Si.

In spite of the excellent properties of mobility, narrow-gap semiconductors not generally used in the sensors based on the Hall effect or magneto-resistive sensors, as they are pure at ambient temperature. This is reflected in low values of the Hall coefficient and Hall voltage, and the voltage change of the Hall and the sensor resistance with temperature. This comes into conflict with an important requirement of the magnetic field sensor, namely its response to a magnetic field should be relatively insensitive to temperature changes. Another consequence of the pure mode is that the Hall effect is nonlinear with respect to the magnetic field (magneto-resistive properties vary in accordance with the square of the magnetic field, regardless of Repola, operating at room temperature (C) or above: in particular, they need to be heavily doped to reduce the temperature dependence of the carrier concentration (i.e., to make their impurity). This leads to the fact that he was losing the sense of purpose of their use, because it reduces the mobility of carriers and significantly counteracts the implementation advantages.

Conventional magnetic field sensors operate in a saturated impurity mode, where the carrier concentration is largely constant, and does not occur undesirable changes in the resistance and Hall effect. The temperature dependence of the resistivity and Hall effect arise, however, due to the decrease in mobility with increasing temperature associated with increased phonon scattering and the initial electron-hole scattering.

The magnetic field sensors of the prior art were based on the technology of silicon, which was physically laborious and was widely used in the transportation industry in harsh environments. They are used, for example, a brushless drive motor compact disc (CD), where priority is low noise. However, the problem avlei for some applications.

The purpose of the present invention is the creation of alternative forms of the magnetic field sensor.

In the present invention proposed a magnetic field sensor that includes a semiconductor sensor with an active area in which the work is formed (generated) signal in response to a magnetic field, characterized in that the sensor element:

(a) is, at least partially, in the mode of pure (native) conductivity in the absence of bias, and at normal operating temperature;

(b) includes the transition, which is shifting to reduce pure conduction in the active region and the limitations of the charge carriers predominantly only one type in accordance with saturated impurity mode, and

(C) includes means for detection (detection) signal generated in the active region (14, e) in response to the applied magnetic field.

A shift of the p-n junctions of this type, as described above, known in the photodiodes of U.S. patent No. 5016073.

This invention provides the advantage is that the magnetic field sensors are made of a material with high mobility, hitherto considered nepoch the ü improved linearity of the Hall effect as a function of the magnetic field: it is a consequence of the reduction of pure conduction, i.e. removal of electrons and holes in equal amounts and changes of conductivity in the valence band and the conduction band to the conduction essentially in one area at the expense of only one carrier. In practice, pure conductivity is not completely excluded, but is reduced to negligible proportions.

A shift of the transition can be a exclusive contact to the exclusion of minority carriers from the active region, and may be homoparental between materials of indium antimonide with different concentrations of dopants or heterojunction between indium antimonide and a material having a wider bandgap than the indium antimonide.

The sensor may be cross-shaped sensor based on the Hall effect with the Central region, from which extend four branches, with at least one branch connected to a exclusive contact to reduce the concentration of minority carriers in the active region at offset (voltage bias), while the first pair of branches attached to the power source, and the second pair of branches attached to the device, measuring the Hall voltage. Each branch can podsetiti, located adjacent to the Central region.

A shift of the transition can be extracting the transition for the extraction of minority carriers from the active region. This may be a transition between two areas of the sensor made of materials having different type of majority carriers and different width of the forbidden zone, and the transition should be thick enough to prevent electron tunneling and be thin enough to avoid relaxing the strain in the materials associated with it. This may be a heterojunction between InSb n-type and In1-xAlxSb, where x ranges from 0.1 to 0.5, or from 0.15 to 0.2, or essentially equal to 0.15.

The sensor may have a cross shape with four branches and a Central region and may have four sequentially deposited layers, of which two adjacent layers have the same type of majority carriers, and the other two adjacent layers have different type of majority carriers, and the transition may be a heterojunction layer between the active region and another layer with a different bandgap and other type of majority carriers, and the first pair of branches attached to the current source, the second pair of branches (14b, 14d) attaches is in the opposite direction, by connecting the substrate of the sensor. Four sequentially deposited layer may have a structureand the second pair of branches may have a tapered portion located adjacent to the Central region. The second pair of branches may have a contact area, which adjoins the Central region and is less than 10% of the width of each branch of the first pair of branches.

The transition can be positioned to highlight the flow of current in a direction essentially orthogonal to the deflection of charge carriers due to the magnetic field during normal operation.

The active area of the sensor can be p-type and have extracting a shift of the transition. It (the sensor) can be provided with dominant source of charge carriers in the form of a layer with-alloying impurities. It may include quantum pit, creating it the current path. The sensor itself may be a diode structure of the form- quantum well.

Alternatively, the sensor may have a diode structure of the form.

In another aspect the present invention provides a method of detecting a magnetic field, otlichalsya in itself semiconductor sensor element active region, in which during operation is formed (generated) signal in response to a magnetic field, and the sensor element is at least partially, in the mode of unalloyed conductivity at normal operating temperature in the absence of bias, and has a passage that is offset to reduce the pure contribution to the conductivity in the active region and the limitations of the charge carriers predominantly only one type in accordance with saturated impurity mode;

b) displacement of the active area of the sensor and the transition to ensure the flow of charge carriers in the active region and the operation of the sensor in accordance with saturated impurity mode, and the application of a magnetic field to the active region; and

c) detecting the signal generated by the active region, at least partially, in response to a magnetic field.

Phase offset active area of the sensor can be carried out at a constant voltage, and phase detection signal includes a detection voltage signal.

The sensor may be a sensor based on the Hall effect, and phase offset active area of the sensor includes the application of constant current, and phase of the signal detection includes detection is and it will be described the embodiments with reference to the accompanying drawings, where:

Fig.1 is a schematic view of the magnetic field sensor according to the invention in the form of a device based on the Hall effect;

Fig.2 represents a sectional view along the line II-II of Fig.1;

Fig.3 represents the energy band structure of the sensor of Fig.1 and 2;

Fig.4 shows the energy band structure of another sensor according to the invention; and

Fig.5 illustrates another sensor according to the invention; and

Fig.6 is a cross-section on the line VI-VI of Fig.5;

Fig.7 is an energy band diagram for the sensor of Fig.5;

Fig.8 illustrates the Central region of the sensor of Fig.5;

Fig.9 gives a different geometry for the sensor shown in Fig.5;

Fig.10 illustrates the contributions to the electron mobility in the material InSb n-type under different conditions of operation of the transducer;

Fig.11 illustrates the effect of temperature changes on the Hall coefficient RHfor equilibrium and extracted InSb;

Fig.12 is an illustration of the change of the Hall coefficient RHwhen changing the density of the magnetic flux for both equilibrium and extracted InSb;

Fig.13 is a circuit for the sensor of Fig.1;

Fig.14 is a circuit for the sensor of Fig.5;

Fig.15 presented is a; and

Fig.16 represents a sectional view of a magneto-resistive sensor according to the invention, which includes quantum pit.

With reference to Fig.1 and 2 show the magnetic field sensor 10 based on the Hall effect according to the present invention, shown in plan and in cross section respectively. It includes cross layer 12 of indium antimonide (InSb) n-type with four branches with 14a through 14d (General designation - 14) coming from the Central square region 14, and the branches 14a and 14C are orthogonal (perpendicular) relative to the branch 14b and 14d. The peripheral length of the side branches 14 covered areas 16A through 16d (General designation - 16), each of which consists of a layer of InSb n-type with the appropriate designation from 17A to 17d (General designation - 17), which are aluminum (Al) electrodes 18a through 18d (General designation 18), respectively. The Superscript “+” in the designation “n+means much higher concentration of dopant than in the layer 12.

The sensor 10 has an insulating substrate 20 made of sapphire, silicon with high resistivity (> 50 Ohm/square) or insulating GaAs. As illustrated, the InSb layer 12 is attached to the substrate 20 using CL is ireh electrodes 18 creates ohmic contact with the respective layer 17 InSb n+-type and connected to the connecting wire 19.

Fig.3 is a graph 30 of the energy band structure for the layers 12 and 17 InSb n-type and n+-type, respectively. It shows the area 32 of the conduction and valence zone 34 for unbiased n+n junction 36 between the layers 17 and 12, with parts 36b and 36d in Fig.2.

The sensor 10 operates as follows. It is a device with the exception of the minority carriers, in which each layer 17 of n+-type forms the n+-hampered 36 with the underlying layer 12 of n-type. As described previously, the exception carriers known to date in relation to the photodiodes of U.S. patent 5016073 issued to Elliott and Ashley (Elliot and Ashley). The bias voltage is applied between the contacts 18a and 18C on opposite branches 14a and 14C, the contact 18a is positive with respect to pin 18C. Contacts 18b and 18d on mutually opposite legs 14b and 14d are voltage detectors for measuring the Hall voltage. As the layer 17 of n+-type heavily doped, it has a negligible concentration of minority carriers (holes). Consequently, he is able to take the main carriers for the fleece inside. n+n-Hampered 17A/12, or 36, therefore, is an exclusive contact, i.e., the electrons (the majority carriers) easily pass from layer 12 to layer 17A, but much less current due to holes (minority carriers) flows in the opposite direction from the layer 17A to the layer 12.

In addition, holes are removed from the layer 12 on the opposite n+n-homoparental between layers 17c and 12. Subsequently, the application of a bias voltage between the contacts 18a and 18C leads to the fact that the concentration of minority carriers in the layer 12 becomes smaller because the holes are removed from it, but their number is completely re not updated. The concentration of majority carriers in this layer may fall to the same number as the concentration of minority charge carriers, are derived from the rules electroneutrality; therefore, the number of electrons and holes is reduced equally, which reduces the pure contribution to the conductivity of the layer 12 (the reduction of the impurity contribution will be to act only on the type of majority carriers). The excluded region, i.e. the region where the number of charge carriers decreased thus passes through the layer 12 in the branches 14b and 14d between layers 17A and 17c n+type.

The electrode material of CR-Au em - more of a thick layer of Au.

As marked with signs 39A - 39C, the previously described parts have the same reference position, each layer 17 InSb n+-type may be replaced by a layer 40 of materialtype, or, alternatively, two layers, layer 41-type and a layer 42 of n+-type; emphasis here(and later alsothis refers to the material with a larger bandgap than nepoddelnuyu equivalent; for example, Fig.4 represents a diagram of the energy band structure showing the substitution effect layer 17 layer 40 of material-type of In1-xAlxSb with x=0,15. Area 43 of the conduction and valence area 44 is shown for unbiased-heterojunction 46, is formed between the layer 40-type and layer 12-type InSb.

Layer 40-type has a low concentration of minority carriers (holes) because of its large width of the forbidden zone leads to a smaller number of electron-hole pairs are excited by thermal image than for jet holes from the layer 12 of n-type, that can't be replaced from the layer 40-type because of their lack of the latter. Similar comments apply to the layers 41 and 42.

Now with reference to Fig.5 shows another sensor 50 on the basis of the Hall effect in accordance with the present invention. It includes a cross-shaped structure 52 of indium antimonide (InSb) n-type with four branches with 53A through 53d, going from a square Central region a (General designation - 53), and branch 53A and s are orthogonal with respect to the branches 53b and 53d. The peripheral length of the side branches 53 is covered by a layer 54A through 54d of InSb n+type (General designation - 54), which are aluminum (Al) electrodes (not shown). The sizes of the branches 53 and the Central region e are indicated by the parameters a, b and C, where:

a = length of branch 53 + square side e

b = the length of the branch 53

C=a-b = width of the branch 53=side of the square e

Fig.6 is a cross-section on the line VI-VI in Fig.5, perpendicular to the plane of the latter, showing the layer structure of the sensor 50. It is shown not to scale. The sensor 50 includes a layer 64 with a thickness of 2 microns of material InSb p+-type substrate 62 of InSb or GaAs. Layer 64 In1-xAlxSb R+-type with a value of x in the range from 0.1 to 0.5, preferably from 0.1 to 0.2, for example, of 0.15. Layer 66 is covered with a layer 53 with a thickness of 0.5 μm from InSb n-type, which consist of branches and the Central part 53. Electrode layers 54b and 54d at the ends of the respective branches 53 have a thickness of 0.3 μm and made of InSb n+type. Layers 54 n+-type layer 53 of n-type and the layer 66type each have two end surfaces lying in respective planes 74 and 76 and the corresponding end surfaces of the branches 53. The end faces 74 and 76 adjacent to the protective layer 78 of the oxide formed on the layer 64 of InSb p+type. On the other hand, instead of the protective oxide layer can be used a layer of polyamide. All contact layers 80 and 82 are formed on each region 54 of the InSb n+-type and on adjacent protective layer 78 of the oxide. The substrate 62 has a fifth ohmic contact 84, which is made from aluminium.

Fig.7 describes the band structure of the sensor 50 in the absence of any applied bias, and contains an area of 102 conduction, valence zone 104 and 106 Fermi. Layers 54 n+-type form four n+n-homoparental with branches 53 n-type at the first border mazloum 66-type on the second border section 110; layer 66-type forms-heterojunction layer 64 R+-type on the third surface section 112.

Layer 66type forms a barrier in the zone 102 conduction impeding the flow of electrons from the layer 64 R+-type layer 53 of n-type and a layer 54 of n+type.

The sensor 50 operates as follows. Semiconductor layers 64, 66, 53 and 54 form a four diode structures, two of which are shown in cross section in Fig.6. Layers 64, 66 and 53 and-switch 110 are common to all four diodes, but each has a separate layer 54, as shown in Fig.5.-Switch 110 is shifted in the opposite direction by application of a voltage between the electrode substrate 84 and one of the surface electrodes 80 or 82. This has a significant impact on the extraction of minority carriers from the region 53 of n-type.

The principle of extraction media known from the prior art and is described, for example, in European patent EP 0167305 and U.S. patent 5016073. He is the removal of minority carriers from the semiconductor region the major carriers and on which they are extracted and are lost to the region. The carrier transport through the interface 110transition contains:

(a) the current conduction of majority carriers with sufficient thermal energy to overcome the potential barrier of the transfer; and

(b) diffusion current of the minority carriers that diffuse to the junction and pass through it due to the potential difference.

Thus, the carrier transport through the interface 110, 112transition contains:

(a) the current conduction of holes from the area 64 p+-type region 53 of n-type;

(b) diffusion current of electrons from the field of 64 R+-type region 53 of n-type, it is very small, because there are a small number of electrons in the regions R+and;

(c) the current conduction of electrons from the field 53 of the n-type region 64 R+-type, which is also very small; and

(d) the diffusion current of holes from the field 53 of the n-type region 64 R+type.

The following qualitative description of the work negligibly small electron currents are ignored.

In the absence of displacement of electron and hole currents of conductivity and diffusion currents through each boundary 108, 110, 112 are balanced, i.e., the sensor 50 is D/img_data/83/838533.gif">the transition at the interface 110 is shifted in the opposite direction, therefore, minority carriers (holes) in the cross layer 53 of n-type, which diffuse to the interface 110, pass through it due to the potential difference (potential drop). At the same time, this potential difference reduces the flow of holes from the layer 66 is a cross-type layer 53. Therefore, the offset in the opposite direction reduces the current of conduction electrons from the cross layer 53 to the field of 64 p+-type and current conduction of holes from the field of 64 R+-type to a cross layer 53. Therefore, holes are removed from the field 53 of n-type by diffusion and can not be completely replaced due to the conductivity of region 64+-type due to the potential barriertransition is shifted in the opposite direction at the interface 110. As noted earlier, is the effect of extraction of minority carriers.

Cross layer 53 of n-type takes a negligibly small current of holes (minority carriers) from the layer 54 of n+-type, so that the concentration of holes is very small: it is the effect of the exclusion of minority carriers. Therefore, holes in the layer 53, diffusing to the border section the OEB 54 n+type, and, consequently, the concentration of minority carriers in cross layer 53 is reduced. As described previously, based on the need to respect the electroneutrality concentration of majority carriers should fall to the same value as the concentration of minority carriers, i.e., the concentration of electrons and holes fall equally in accordance with the reduction of electron-hole pairs: consequently, this reduces the pure contribution to the conductivity cross layer 53.

When the sensor 50-switch 110 is shifted in the opposite direction, and the sensor 10 operates with a bias current flowing between the opposing pairs of contacts 16A/16C, and a positive contact is exclusive. Both sensors, 10 and 50, work with layers 12 and 53 of n-type having a concentration of electron-hole pairs below the equilibrium; these layers are active areas for measurements of the magnetic field, and the Hall voltage detected through the pair of contact layers 16b/16d and 54b/54d. In the sensor 10, the carrier concentration above the equilibrium near the negatively biased contact due to the accumulation of carriers.

Fig.8 is a three-dimensional image of the Central square section e date is I. Axis of a Cartesian coordinate system is shown as 122 for use in determining the directions of the magnetic field and current. The surface of the Central square section e located in the XY plane, has a pair of sides parallel to the axes X and Y respectively and perpendicular to the axis Z. the current through the sensor 50 has first and second component of Iplaneandindicated by the arrows 124A beaches and 124b. The first component of the currentplaneflows parallel to the X axis essentially inside the layer 53 of n-type and between opposite branches 53A and s.

The second component of the currentflows parallel to the Z axis and appears as a result of displacement of the boundary line 110-transition. Strictly speaking, the current does not flow inside the area e, but consists of four components flowing to the respective end segments 54 on the branches 53 and is included in the drawing of Fig.8 for ease of reference. This current occurs due to thermal generation of charge carriers in the layer 53 of n-type, and therefore, the associated flow of holes is essentially homogeneous in the direction parallel to the Z axis down to the layer 66-type, while the stream of electrons flowing in the lateral direction is only under the areas 54 n+type.

Voltage is applied between the regions 54A and s to establish the current Iplanethat corresponds to a current density jxflowing parallel to the axis X. again referring to Fig.6, it can be seen that the sensor 50 is subjected to electric fields as extraction and conductivity. Field extraction is applied between the electrode substrate 84 and each of the four final layers 54A through 54d on the respective branches. Field conductivity is applied between the first pair of end layers 54A and s on opposite branches. Field extraction leads to the growth component of the currentwhich is diode leakage current, parallel to the axis Z. Field conductivity gives the component of current Iplanewith the current density jxthat is essentially the flow of electrons in the layer 53 of n-type, because the boundary 110junction acts as a barrier to penetration of the field layer 64 of p-type. The sensor 50 is located in a magnetic field BZparallel to the axis Z and, therefore, orthogonal to the plane of Fig.5. Current Iplaneand the magnetic field Bz form (generate) parallel to the Y-axis of the Hall voltage in the Central obl.

Current Iplaneessentially limited to the layer 53 of n-type, and the Hall voltage, respectively, appears inside this layer. However, due to the properties of the extraction and exclusion of the media, the inherent structures-type in the sensor 50, pure contribution to the carrier concentration is reduced, as described above. Conductivity and Hall effect are predominant due to the impurity of the conductivity in the saturated impurity mode with carrier concentration, largely independent of temperature. In addition, extraction reduces the carrier concentration, which reduces the electron-hole scattering, and this affects the mobility of carriers, which, in turn, becomes less sensitive to temperature changes.

With reference to Fig.9 shows an alternative form of the sensor 128. It corresponds to the sensor 50 (the same parts have this designation), except that it has a branch 53b and 53d, sensitive to the Hall voltage, which taper to a width d in the vicinity of the Central part e. Where narrowing no, all branches of the 53 have a width, and the width d is less than C; d is preferably less than one-tenth C.

When the sensor 50 minority novtel is img> therefore, should be extracted charge carriers not only from the ends of the branches with 53A through 53d, but also with a layer 53 of n-type through the Central region a. The length of each branch with 53A through 53d together with the Central node a, i.e., the dimension a should be sufficiently short to ensure that extraction could extend through the branch 53A - 53d and the Central node e. However, the path length over which there is a Hall effect must be large enough to allow charge carriers to deviate and to generate a measured signal.

The limitation of the sensor 10 is necessary to prevent the accumulation of charge within the Central region 14. When the final layers 16A and 16C branches served the bias voltage, the charge accumulated on any of them, has a negative offset with respect to another. Accumulation should occur far enough away from the Central region 14 to ensure, in order not to decrease the exception of the media. Therefore, this provides a minimum length for each branch 14a-14d (dimension b in Fig.5), which is determined by the operating conditions of the sensor and is limited by the diffusion length in an upward direction Ldwhich the media;

k - Boltzmann constant;

T is the absolute temperature of the sensor; and

l is the diffusion length of the carrier in zero field.

The diffusion length of the carrier in zero field 1 is given by the formula

where D is the diffusion coefficient of the charge carrier; and

- the average lifetime of the charge carrier.

In the sensor 50, the current Hall-Iplaneexposed to diode leakage currentTo reduce this impact Iplaneshould be, preferably, much more thanHowever, currentdepends on the bias voltage Vbias-the structure of the sensor 50, and Vbiasshould be large enough to ensure the efficient extraction. On the other hand, Iplanecan be as large as possible within the limits established at the expense of power density, which sensor 50 can be prevented. This implies a small cross-sectional area, through which flows a current Iplaneand is achieved by reducing the height of tZn-layer and the width C. the Minimum height of the layer 53 of n-type is determined by the width of the depletion region, which it supports, the La this level dopant and power offset only width-side cross-shaped structure 53 is the remaining variable parameter. Appropriate values will be discussed later.

Similar comments apply to the sensor 10, for which the bias voltage should be large enough to provide adequate exceptions carriers.

The sensors 10 and 50 show improved results when compared with the equilibrium devices of the prior art, as shown graphically in Fig.10-12. These drawings are based on calculations involving the layer 53 of InSb n-type with a concentration of donor impurities 1016cm-3. They include the contribution of impacts on the Hall effect both electrons and holes and, therefore, are more complex than the approximation given earlier. The carrier concentration and, hence, also the Hall coefficient in the sensors 10 and 50 are not completely independent of temperature, but the change is quite small (approximate change by 30-40% when the temperature changes at 50K) for a number of applications. The examples described below, improve these values.

In the sensor, where the contribution to conductivity make the media more than advised from the magnetic field (see, for example, kN. “Hall Effect and Semiconductor Physics” E. H. Putley, published by Butterworth and Co., 1960, Chapter 4). The dependence on the magnetic field is more pronounced for materials with higher mobility than silicon.

From equations (2) and (3) by substituting the expression for the current density

where tz- sensor size in thickness in a direction parallel to the magnetic field,

Ix- longitudinal current sensor orthogonal to the magnetic field and field Hall, and other parameters determined previously.

In Fig.10 shown four curves 132-138 of electron mobilityedepending on the temperature for InSb n-type for different scattering mechanisms and environments. Here is illustrated by the temperature sensitivity of the Hall coefficient RHfor narrow-gap semiconductors, where both electrons and holes contribute to the conductivity. The first curve 132 corresponds to the mobility, which affects only the scattering due to ionized impurities and electron-hole interactions. The second curve 134 shows the temperature change of such components mobility, which is exposed to the optical phonon to rasseyannoi the first and second curves 132, 134. These three curves 132, 134 and 136 were obtained on the basis of the equilibrium carrier concentration. The fourth curve 138 represents the change in mobilityewith the temperature T, when was extracted pure contribution to the conductivity.

Comparison of the curves 136 and 138 shows the advantage of the effect of extraction media for sensors in accordance with this invention, because the extraction increases mobility at temperatures above approximately 250K: the difference between the equilibrium curve curve 136 and 138 extraction becomes more noticeable at higher temperatures, resulting in large values of the Hall coefficient and the strengthening of the magneto-resistive properties. Comparison of the gradients of these two curves shows that the change in mobility with temperature T is also slightly decreases due to the extraction. This reduces the temperature dependence of the Hall coefficient and magneto-resistive properties.

In Fig.11 depict two curves 142 and 144 for the Hall coefficient RHdepending on the temperature of the semiconductor InSb in a magnetic field of 0.3 T at equilibrium conditions and extraction, respectively. On the equilibrium curve 142 RHfalls approximately on atural sensor 50 when exposed to extraction of minority carriers in accordance with the invention; here RHessentially does not depend on temperature in the same interval, demonstrating the advantage of the sensor according to the invention in relation to their insensitivity to temperature.

Fig.12 shows four curves 152, 154, 156 and 158 for the Hall coefficient RHdepending on the applied magnetic field for both equilibrium and extracted InSb under different temperature conditions. It illustrates the sensitivity of RHto the magnetic field for narrow-gap semiconductors in pure mode, when both electrons and holes contribute to the conductivity. Curve 152 built for sensor according to the invention with extraction and shows that RHis at least substantially independent of the magnetic field. Curve 154 is constructed for the sensor under equilibrium conditions and a temperature of 200K and shows that RHonly slightly depends on the field - there is a decline of approximately 3% between 0.1 and 1.5 T. the Curves 156 and 158 built for the sensor under equilibrium conditions and a temperature of 300 and 400K respectively. They show thatHchanges the sign and between 0.1 and 1.5 T decreases from +200 to -10 cm3In one case, and from +30 to -50 cm3In the other case. It shows soglasno the invention, which affect their work, are as follows:

(a) operating temperature range sensor: the current density of the sensor increases with operating temperature (for example, C), which may cause charge carriers with sufficient energy to overcome the barrier at the interface 110;

(b) the composition of the In1-xAlxSb barrier layer 66: table. 1 below shows the density of the leakage current as a function of the working temperature sensor for a range of materials barrier (values of x) and the concentration of donorsd;

(c) electric current: diode leakage currentpreferably amounts to 1% of the current Hall-Iplanealthough acceptable measurement accuracy of the sensor can be obtained with the currentconstituting approximately 10% of the current Iplane;

(d) the concentration of the dopant layer 53 of n-type: it limits the maximum current;

(C) power density: it should be limited to a supported level inside layer 53 in order to avoid thermal care, for example, it is approximately 100 W/cm2. For the sensor 50, the power density of the Pdis given by the formula

where Iplanethe current flowing in the plane layer 53; - the Lin the path of the current sensor; and

tz- the thickness of the layer 53;

(f) applied voltage: in addition to the Hall voltage VHthe other two voltage associated with the sensor 50: voltage Vbias(for example, 0.5 V) between the electrode substrate 84 and the electrode 80 or 82 branches shifts in the opposite direction-transition 110; voltage Vdrivebetween the opposite branches 53A and s controls the current Iplane. Voltage Vbiasextracts of thermally generated charge carriers from the region of n-type, while it affects the thickness of the depleted layer extracting PN junction;

(d) thickness tza layer 53 of n-type must be essential to maintain the depleted PN-layer, the doping level of 1016cm-3and voltage Vbias1, it is preferably 0.5 microns;

(n) the thickness of the layer 66-type is preferably 20 nm. This layer provides a barrier thickness of about 10 nm or more, sufficient to prevent electron tunneling. The barrier is sufficiently thin (<30 nm) to prevent deformation between it and the adjacent layers of InSb.

A theoretical model for the sensor 50 has been used is in the surrounding area of the leakage currentas a function of absolute temperature T for various levels of doping of Ndand parameters x of the composition of the material In1-xAlxSb.

For values of x and Ndshown in the table. 1, PL. 2 gives the other parameters of the sensor for temperature of 370K and the relationship of the leakage current to the current in plane/Iplanlimited to values from 0.9 to 1.1%.

The values in the table. 3 equivalent values from table. 2, except that the relation/Iplaneincreases and ranges from 10% to 12%. The sensors 10 and 50 may be relevant/Iplanein the range from 1 to 10%.

Table. 1 shows the difficulty of keeping the density of the leakage current j1at a suitable level at higher operating temperatures So the Increase of the parameter x of the composition of the barrier layer 66 reduces the density of the leakage currentand current management should maintain a constant attitude/Iplane; this also reduces the dissipation (dissipation) of energy sensor. For example, changing the x in the composition of from 0.15 to 0.25 p15cm-3corresponds to the working temperature of approximately 200K in contrast C.

Table. 2 shows that, when the impurity concentration of 1015cm-3it becomes difficult to detect the conditions under which the power density of the Pdremains suitable for reliable operation of the sensor, even with a large part of the barrier. On the other hand, the increase of impurity concentration from approximately 1015cm-3to about 1017cm-3reduces the mobility of carriers is approximately 3 times. In addition, the proximity regions of n-type regionstype can cause tunneling of carriers that contribute to the current densityTherefore, PL. 2 shows that the optimal concentration of dopants is approximately 1016cm-3; the path length of the current sensor, 5 ám, gives a suitable power density Pd124 W/cm2.

Table. 3 shows that the increase of the ratio/Iplaneenables you to use large sensors: the latter is easier to produce and sustain high currents equivalent power density, giving Bo the battery (battery) 210 with positive and negative pins 212 and 214 is connected directly to terminal layer 16C branches and through a series of resistors RL- end layer 16A branches, respectively.

The battery 210 shifts the limit layer 16C in a positive direction with respect to the end layer 16A, and generates a current Iplanethrough the end layer 16C, a branch 14C, the Central region 14, the branch 14a and the terminal layer 16A. Because of the positive bias terminal layer 16C is an exclusive contact towards the active region 14 of n-type, which, consequently, leads to a decrease in equal amounts of electrons and holes, as described previously, largely destroying the pure contribution to the conductivity. The exclusion zone passes through the branch 14C, the Central region 14 and the branch 14a. If a magnetic field is applied perpendicular to the plane of the drawing, the Hall voltage appears between regions 16b, 16d. The current flowing between the magnetic layer 16C and the layer 16A, mainly exists only due to media of the same type, i.e., the electrons are donor impurities, and the sensor operates in a mode that simulates saturated impurity mode of material with a wider bandgap, such as Si.

Now with reference to Fig.14 shows a circuit 300 for the sensor 50. The circuit 300 has a first battery 310 with positive Sledovatelnot resistors RS- end layer 16A branches, respectively. A second battery 320 is negative, the output 322 is connected through a sequence of resistors RBconnection 330 of the substrate of the sensor, and a positive output 334 connected to region 16C and to the negative terminal 314 of the first battery.

The first battery 310 supplies the bias voltage to the sensor 50 through the resistor RSand the current Iplaneflows between the leaf layers 54A and s through the branch 53A, Central region a and branch C.The second battery 330 moves the substrate 62 (see Fig.6) in relation to leaf layers 54A and s that moves in the opposite direction-heterojunction 110 between the layers 53 and 66. Layer 66 acts as an extracting contact with respect to the layer 53, which then largely destroyed pure contribution to the conductivity. Current Iplanein the layer 53 is, therefore, primarily exists due to only one type of charge carriers, i.e. electrons, activated from the donor impurities and the sensor 50 operates in a mode that simulates saturated impurity mode. If the magnetic field is perpendicular to the plane of the drawing, the sensor 50 generates a voltage Halticinae sensors work well in the variant with current control, when the sensor current is kept constant, and the changes in voltage are detected in order to determine the magnetic field In the sensor based on the Hall effect is given by the relation

where all the parameters are defined earlier.

From equation (1) followed by a

where VD- longitudinal voltage that controls the current Ixthrough the magneto-resistive sensor;

transforming, we get

In the variant with control of the current measured value of the field In depends on the carrier concentration n, which is exposed to noise generation-recombination in the semiconductor and also affects the measurement. Sensors with extraction of charge carriers subject to the influence of 1/f noise or due to fluctuations of the carrier concentration, or because of fluctuations in the mobility. Existing (inconclusive evidence in favor of fluctuations of concentration: therefore, in the case of working with current control and the read voltage will affect the influence of 1/f noise.

Alternative work for a magnetic field sensor according to the invention is the control voltage, i.e., operation at a constant control voltage and will remain in equation (12), as for the sensor based on the Hall effect it is obtained from the following equation:

where lx- the length of the sensor and the other members defined above.

In the variant with control voltage of the measured value does not depend on carrier density and depends only on the temperature due to the temperature dependence of mobility: the latter is a slow change and also prevents the effects due to changes in the concentration of any remaining media, as there are two opposite effects. In addition, this measured value will not be exposed to noise generation-recombination or 1/f noise, if the latter occurs due to density fluctuations.

Option control voltage is not commonly used, because it can lead to thermal runaway and instability of the sensor. However, the sensor according to the invention is stabilized against thermal runaway, as the latter is due to pure conduction, which in the invention is reduced. Moreover, in this variant does not require reduction of the pure contribution to such an extent as in the other embodiments, to obtain equivalent performance. Also schitaetsa work with the current control.

Another alternative is the operation of the sensor based on the Hall effect according to the invention in the variant with current control and current sensing: in this embodiment, the sensor current Ixis kept constant, and the Hall voltage is used to control the current in the external circuit connected across the electrodes, measuring the Hall voltage, and the latter current is measured. This option should, in principle, have the same benefits as option control voltage and the read voltage. Picture of the current flowing through the sensor in the variant with current control and current sensing is complex and requires numerical simulation for a full assessment. The current sensing is used when there is a need for device management directly using the output signal of the sensor.

Now with reference to Fig.15 shows in cross section of a magneto-resistive sensor 400 according to the invention, but, as noted zigzag lines, such as 402, the drawing is made without complying with the scale. Parts equivalent to the parts shown in Fig.6, have the same links with the previous number 400. The sensor 400 includes a layer 464 substrate with a thickness of 1 μm of InSb p+-type Podlaskie, if you want to. Layer 464 is covered with a layer 466 thickness of 20 nm of In1-xAlxSb R+-the type of x in the range from 0.1 to 0.5, preferably from 0.1 to 0.2, for example 0,15. Layer 466 is covered with a layer 404 with a thickness of 0.5 μm, consisting mainly of InSb p-type dopant concentration 31015cm-3but including 30 nm below the surface 406 ultrathin layer 408 silicon dotted line: layer 408 silicon is considered-doped layer. When working-doped layer 408 creates a two-dimensional electron gas with a concentration in the range of 61011cm-2to 21012cm-2for example 11012cm-2.

Two areas 411 of InSb n+-type with a thickness of 30 nm are applied to the layer 404, creating the electrical connection to it: it allows you to measure the voltage in the sensor 400 and, therefore, to determine the resistance of the sensor to provide a measurement of the magnetic field. They are separated by a distance in the range from 2 to 5 μm, for example 3.5 µm. In terms of sensor 400 is as shown in Fig.1, except that it has no branches 1 which covers the extraction media when the applied reverse bias, i.e. when one of the electrodes 411 is shifted in the positive direction with respect to the substrate 462. This is because the boundary between layers 411 and 404 represents the n+p-transition, which is extracting contact under reverse bias. The carrier concentration is reduced to concentrations that are much less pure concentration prevailing in the absence of bias, and it becomes largely independent of temperature, as in a saturated impurity mode.

Conductive layer of the electrons generated in the p-layer 404 usingdoped layer 408: electrons form a two-dimensional gas concentration, which also remains largely constant when the temperature changes, because it is due to the concentration of the dopant, and not due to thermal activation. Electrons from-alloying layer A are the dominant source of charge carriers in p-layer 404, which is an active area of the sensor. n+Layers 411 act as a connection source and a drain of the p-layer 404, which creates a conductive path between them. It is the resistance of this conductive p. the use of which is measured magnetic field.

The mobility of minority carriers (electrons) and hence also e diffusion length are much higher in the semiconductor material of the p-type than the hole mobility in the equivalent n-type effect extraction of carriers takes place during the diffusion length of minority carriers, and, therefore, of the two types of conductivity of the material p-type experiences much more efficient extraction, and the carrier concentration has a higher degree of temperature independence. In the sensor 400, the carrier concentration and the resistance R0change with the temperature change at 50K approximately 2%, which is essentially constant for many applications.

Now with reference to Fig.16 shows the cross section of a magneto-resistive sensor 500, but, as marked with zigzag lines, such as 502, the drawing is made without complying with the scale. The sensor 500 includes a layer 504 with a thickness of 1 μm R+-type of Inof 0.85Alof 0.15Sb with a concentration of dopant 21018cm-3. Layer 504 is located on the substrate 506 of InSb or CAAS and has contact 508 with electric shift, which can be removed to a greater distance. Layer 504 bears slo is carried out impurities - their concentration is less than 11016cm-3. Layer 510 coated quantum pit 512 thickness of 15 nm from InSb p-type dopant concentration 31015cm-3. Quantum well 512 is covered with a layer 514 of a thickness of 150 nm (a suitable range of thicknesses in a range from 100 to 200 nm), consisting mainly of Inof 0.85Alof 0.15Sb-type, which nominally doped with impurities at a concentration less than 11016cm-3. Layer 514type includes-alloying layer 518 n-type silicon on quantum pit 512 and removed from it at a distance in the range of 10-40 nm. When working-alloying layer 518 creates a two-dimensional electron gas with a concentration in the range of 61011cm-2to 21012cm-2for example 11012cm-2which is formed in the quantum well 512 due to its energy advantage: this is referred to as the doping type and concentration of the electron gas also remains constant when Elektricheskie connection: they allow you to measure the voltage in the sensor 500 and therefore, to determine the resistance of the sensor to provide a measurement of the magnetic field. They are separated by a distance in the range from 2 to 5 μm, for example 3.5 µm. In terms of the sensor 500 is as shown in Fig.1, except that it has no branches 14a and 14C.

The sensor 500 is a diode structure-quantum wellin which quantum well 512 feels extraction media, when applied reverse bias, i.e., one or both of the electrode 520 is shifted in the positive direction with respect to the substrate 506. This is because the boundary between layers 514 and 520 represents the n+p-transition, which is extracting contact under reverse bias. The carrier concentration in the quantum well 512 is reduced to a level that is considerably lower pure equivalent in the absence of bias, and here again it becomes largely independent of temperature, as in a saturated impurity mode. Electrons from-alloying layer 518 are the dominant source of charged carriers in the quantum well 512, which is an active area of the sensor. Other areas sitela can be considered permanent.

Layers 520 n+-type act as electrodes and source and drain between which there is a pathway throughlayer 514 and quantum pit 512. It is the resistance of this pathway depends on the magnetic field and allows to measure the magnetic field.

In the sensor 500, the carrier concentration changes with changing temperature on 50K less than 1%: this is a very high degree of permanence, which is suitable for the required applications. This gives advantages when compared with previous versions, because the carrier concentration in the quantum well is determined by the doping with modulation, which is a fixed parameter in contrast to thermal activation of electron-hole pairs.

The layer structure shown in Fig.6, 15 and 16, can be used to create and sensor based on the Hall effect and magneto-resistive sensor. The difference between the two types of sensors is simple: the first has a configuration with four pins, as in Fig.1, and the last has a configuration with two terminals, corresponding to the absence (or non-use) of branches 14b and 14d.

Claims

1. Magnetic sensor operation, a signal is generated in response to a magnetic field, characterized in that the element (10, 50) of the sensor (a) is, at least partially, in the mode of pure conduction in the absence of bias, and at normal operating temperature; (b) includes a passage (36, 110), which is a move to reduce pure conduction in the active region (14, e) and restrictions of charge carriers predominantly only one type in accordance with saturated impurity regime, and (c) includes means for detecting the signal generated in the active region (14, e) in response to the applied magnetic field.

2. The sensor under item 1, characterized in that the transition is a exclusive contact (36) to prevent minority carriers from the active region (14).

3. The sensor under item 2, characterized in that exclusive contact (36) is homoparental between materials of indium antimonide with different concentrations of dopant.

4. The sensor under item 2, characterized in that exclusive contact (36) is a heterojunction between indium antimonide (12) and the material (40,41), having a wider bandgap than the indium antimonide.

5. The sensor under item 1, characterized in that it is cross-shaped sensor based on the Hall effect with Central asset is, for example, 14a) connected to exclude the contact (e.g., 16A) to reduce the concentration of minority carriers in the active region at the offset, with the first pair of branches (14a, 14C) is connected to the current source, and the second pair of branches (14b, 14d) is attached to the device, measuring the Hall voltage.

6. The sensor under item 5, wherein each of the second pair of branches (53b, 53d) has a tapering portion adjacent to the Central active area (e).

7. The sensor on p. 5, characterized in that each branch (e.g., 14a) connected to a corresponding exclusive contact (e.g., 16A).

8. The sensor under item 1, characterized in that the transition is extracting transition (110) for the extraction of minority carriers from the active region (a).

9. The sensor under item 8, wherein extracting the transition (110) is a transition between two areas of the sensor made of materials having different type of majority carriers and different width of the forbidden zone.

10. The sensor under item 8, wherein extracting the transition (110) is a) is thick enough to prevent tunneling through him electrons; and (b) sufficiently thin to avoid relaxing the strain is a heterojunction of indium antimonide (53) n-type and In1-xAlxSb (54), where x is in the range from 0.1 to 0.5.

12. The sensor under item 10, characterized in that x is in the range from 0.15 to 0.2.

13. The sensor on p. 11, characterized in that x is essentially equal to 0.15.

14. The sensor under item 8, characterized in that it has a cruciform shape with a Central active area (e), from which extend four branches (53a-53d), and branches have four consistently applied layer(64, 66, 53, 54), of which two adjacent layers are layers with the main carriers of the same type, and the other two adjacent layers are layers with the main carriers of the other type, while extracting the transition (110) is a heterojunction between the layer (53) of the active region and the other layer (66) with a different bandgap and other types of fixed media, the first pair of branches (14a, 14C) is connected to the current source, the second pair of branches (14b, 14d) is connected to the device, measuring the Hall voltage, and extracting the transition (110) is shifting in the opposite direction by connecting the substrate of the sensor.

15. The sensor under item 14, characterized in that four sequentially deposited layers (64, 66, 53, 54) arestructure.

the e l e C bordering Central region (e).

17. The sensor under item 14, characterized in that each branch (53b, 53d) of the second pair of branches has a contact area adjacent to the Central active area (a) and estimated at less than 10% of the width of the branches of each branch of the first pair of branches (53A, s).

18. The sensor under item 8, characterized in that it is linked to current flow extraction in the direction essentially perpendicular to the deflection of charge carriers due to the magnetic field during normal operation.

19. The sensor under item 1, characterized in that the passage (514/520) is extracting, and the active region of the p-type.

20. The sensor under item 1, characterized in that the active region is a structure of the quantum well (510/512/514).

21. The sensor on p. 20, characterized in that it includes-doped layer located so as to be the dominant source of charge carriers to the quantum well structure (510/512/514).

22. The sensor under item 20 or 21, characterized in that it is a diode structure of the formquantum well.

23. The sensor under item 1, characterized in that it includes-legsto.

24. The sensor on p. 23, characterized in that it is a diode structure of the form.

25. The method of detecting a magnetic field, characterized in that it comprises the following stages: a) ensuring the presence of a magnetic field sensor that includes a semiconductor element (10, 50) of the sensor active region (14, e), in which during operation a signal is generated in response to a magnetic field, the element (10, 50) of the sensor is at least partially, in the mode of unalloyed conductivity at normal operating temperature, in the absence of bias, and includes a passage (36, 110), which is a move to reduce the pure contribution to the conductivity in the active region (14, e) and restrictions of charge carriers predominantly only one type in accordance with saturated impurity regime; (b) the offset of the active area of the sensor and transition (36, 110) to ensure the flow of charge carriers in the active region and the operation of the sensor in accordance with saturated impurity mode, and the application of a magnetic field to the active region (14, e); and c) detection of the signal formed by the active region (14, e), at least partially, in response to a magnetic field.

26. The way det at a constant voltage, and phase detection signal includes a detection voltage signal.

27. The method of detecting a magnetic field on p. 25, wherein the sensor is a sensor based on the Hall effect, the phase shift of the active area of the sensor includes the application of constant current, and phase detection signal includes detecting a current signal.

 

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