Photodetector for the infrared region of the spectrum
(57) Abstract:Usage: FPU relates to electronic devices, in particular to the photodetector having sensitivity in the infrared range of the spectrum, multiple or singleton with impurity photoconductivity. The inventive FPU contains a substrate of semiconductor, compensated deep high-z impurity, creating a double negatively charged levels. On both sides of the FPU created conductive bus, consisting of the contact layer in the substrate and deposited material that generates electrical contact with the substrate. The contact layer in contrast to the prototype consists of two fields at 300 K with different impurity concentrations, enriching this layer. The first region of maximum concentration, providing a width of greater than or equal to the length of diffusion of majority carriers. A second area with a concentration of impurities enriched (1 - 2) % above the concentration of small impurities in the substrate. The width of this field must be greater than the length of the shielding media with accurate compensation of impurities. When cooled FPU in the near contact region manifests the transition region n+- n (p+- p) with an injecting properties, the investing of media injected from a contact. The second area allows electrical contact to a compensated semiconductor is divided into two contacts with different functions: the contact film of Nickel and enriched region of the substrate, which is resistive; the second contact region and the substrate, which is an injecting contact. 1 C. p. F.-ly, 2 ill., 3 table. Photodetector FPU relates to electronic devices, in particular to the photodetector having sensitivity in the infrared range of the spectrum, multiple or singleton with impurity photoconductivity.FPU for the infrared region of the spectrum is generally used in pulse mode survey. Photovoltaic parameters of the FPU are determined by the properties of the electrical contact to a compensated semiconductor. When the enable pulse voltage to the FPU from contact injections main current carriers, and part of them is captured on traps. During the pause between pulses is the release of trapped carriers of heat or fotogaleria. The magnitude of the photocurrent is proportional to the current recharge levels of traps.Known photodetector (C. G. Ivanov. FTP, 1979, vol. 9, T. 13, S. 1838 1841), which contains poluprovodnikovogo half of the band gap of the substrate material. The admixture is multiply charged with twice negatively charged level for the major carriers. FPU has an outer layer of the tire is made from a material forming an ohmic contact with the substrate and is transparent to the projected radiation. Photodetector has a number of disadvantages: the instability of the electrical properties of the resulting contact of the outer layer to the substrate, the influence of the surface properties of the substrate and properties of the outer layer on the photovoltaic parameters FPU, poor reproducibility of the technological process in the manufacture of the ohmic contact.Known infrared detector matrix (patent GB N 2125217) containing a substrate made of silicon doped with boron and offset controlled divacancies, on both sides of which are formed conductive perpendicular tires of the Au, which in turn consist of the contact layer, an area of enrichment and metal film deposited on the contact layer. Such contact at low temperatures forms a transition of type n+-n(p+-p), which is formed close to the surface, which leads to a dependence of the properties of the transition from the surface of the contact, the possibility of increasing the photosensitivity.The primary object of the present invention is, firstly, an increase in the photosensitivity FPU in the pulse mode of the survey, and secondly, the increase in the uniformity of the distribution of photosensitivity on the field FPU and obtaining a stable reproducible photovoltaic parameters of the FPU.The positive effect from the use of the invention to create a stable an injecting contact to a compensated semiconductor, which does not depend on the surface properties and metal deposited on the surface and increase the photosensitivity FPU in a pulsed mode in comparison with the stationary regime.This effect is achieved by the fact that in the proposed FPU for the IR region of the spectrum containing a substrate of semiconductor doped shallow donor impurity and accurately compensated deep multi-charged acceptor impurity, creating a double negatively charged levels, on both sides of which a conductive bus consisting of created in the substrate contact layer enriched with specially designed small impurity of the same conductivity type as the substrate, and the applied film of metal, the scrap with a maximum impurity concentration equal to
< / BR>under the condition of L1L the WPPT. where D is the diffusion coefficient of the major carriers: Lthe WPPT.the length of the diffusion of majority carriers; the coefficient of recombination of charge carriers; L1the thickness of the first region and the second region with an impurity concentration of 1 2 higher concentration of shallow donor impurities of the substrate, and their thickness are correlated as follows:
< / BR>where L2the thickness of the second region; to improve the ohmic properties of the metal used film of Nickel.Thus, in the proposed FPU contact layer at room temperature consists of at least 2 areas: the first area enrichment of N++(p++); the second area of enrichment with a lower concentration of n+(p+). When cooled in this contact appears the third transition region of the uniform n+n (p+p), the height of the potential barrier which is equal to the difference between the Fermi levels in region 2 and in the volume of the substrate. In the transition n+n (p+p) there is a plane in which impurities are accurately compensated. Injected carriers captured on traps are non-equilibrium and create additional volume charge, which screens an injecting contact. where Ntnodark concentration of carriers in the conduction band at the exact compensation of impurities; the height of the potential barrier (n+-n) transition.The width of the area 2 must be greater than or equal to the maximum length of the escape transition of n+n(p+p), which is defined by the formula (2) and the condition record
< / BR>The concentration of the injected trapped charge carriers at a voltage limit of filling of traps is equal to the concentration of empty seats on the acceptor level in the substrate. The thickness of the first field must be greater than or equal to the diffusion length of the main current carrier, which is determined by the formula
< / BR>where D is the diffusion coefficient of small impurities in 1 region; -the coefficient of recombination of majority carriers, Nmaxthe maximum impurity concentration in 1 area.In order to fulfill the condition L1Lthe WPPTyou must enter in area 1 impurity concentration
NmaxD/L2dInterfax.< / BR>The contact metal and the region 1 is formed a space charge region with the height of the potential barrieroand the maximum electric field Emaxat a depth equal to otter-substrate. Each area of such contact performs its functions: the first function ohmic (injects) contact metal enriched layer of N++the second region at low temperatures an injecting contact N+region and the substrate FPU, i.e. forms directly injects transition n+-n (p+p). The distribution of the concentration of charge carriers in such a contact is shown in Fig. 1. Next we will show how increasing the sensitivity in the proposed FPU. The concentration of charge carriers injected from the contact is determined by the properties of an injecting contact, the voltage and the dimensions of the elements FPU. In the pulse mode of survey FPU considerable increase of photosensitivity in comparison with the stationary regime. In the first moment when the supply voltage impulse flows injection belovoskey current, the peak value of which
< / BR>dielectric constant; m is the mobility of carriers; V - supply voltage; L is the distance between the electrodes; and S the area of the element. The amount of current in a stationary mode through the same element is expressed
< / BR>where nArt.the concentration of photocarriers in the conduction band in a stationary mode. HC is the pulse duration and pause between them, from the background oblojennosti. The pulse amplitude of the photocurrent is given by the expression
wheretothe capture of carriers in the impurity level;
timp.the pulse duration;pausethe duration of a pause; With parameter-dependent properties of an injecting contact.Increasing the photosensitivity is represented as the ratio of the currents
< / BR>In FPU prototype surface of the substrate is covered with a gold film. Gold in Germany creates acceptor levels.However, technologically reproducible contact cannot be obtained, because the gold by sputtering and subsequent annealing was diffundiruet in germanium at a depth greater than the width of the enriched region 1, therefore, was created much precompositional a thin layer of Ge(Au,Sb), which at low temperatures becomes more resistive than the transition n+n and all voltage drops on this layer, resulting in the loss of an injecting contact properties and photosensitivity.In the proposed FPU when applying Nickel is also its diffusion, however, the region 2 is much greater than the length, which manages to prodifferentiating Nickel, and therefore retained the transition n n, from which the following properties of n+n (p+p) transition and the benefits of such contact.In Fig. 1 shows the distribution of the carrier concentration of the current in the FPU of Fig. 2 FPU based on the structure matrix type: 1 substrate; 2 enrichment of N++=1019cm-3; 3 range of enrichment of N+=1015cm-3; 4 film metal; 5 transition n+- n (p+p).An example of a specific implementation. FPU can be a single-element or multi-element matrix or linear types. The proposed FPU is shown in Fig. 2, FPU consists of a substrate Germany, doped with antimony and compensated silver (1), the enrichment of (2), in which the maximum concentration impurity enrichment 1019cm-3the area of enrichment (3) with a concentration of 1015cm-3, region (5), shown at low temperatures and forming the transition n+n (p+p), and a metal film (4), deposited on a substrate. Concentration in region (5) is changed from 1015cm-3to the concentration of charge carriers in the substrate no.FPU matrix type on one bus which serves the voltage pulses to the other buses connected to the amplifier. In the steady state substrate at room temperature is ora clearly apparent. When cooled to t To the substrate is high impedance and area 2 is transformed into two regions, where one of them low with concentrations greater than (1 2) than the concentration of the shallow donor impurity in the substrate, the second transition region nn (p+p). The height of the potential barrier of the transition is determined by the formula
< / BR>N N++In the prototype
N=N+in our case
The width of the transition n+n is determined by the formula
< / BR>When switching on the voltage pulse media injections of contact, prediffusion area 1 and 2, the carriers recombine. The injected carriers are partially captured in the transition region and into the substrate, creating a non-equilibrium associated charge. This charge screens the contact, the screening length of charge carriers is determined by the formula in the exact degree of compensation
< / BR>Changing the photosensitivity FPU is determined by non-stationary processes in the transition, so the creation of an area 2 allows to form a passage whose width is determined by the length of the shielding carriers on the depth L. In the prototype transition is formed close to the surface of the substrate and properties depend on the surface condition.
v+of 0.14 EV, Ec-0,28 EV, Ec-0,09 eV. If two levels are completely filled, partially filled and the upper, nois determined by the formula
< / BR>The concentration of photocarriers is determined by the formula
< / BR>where NSbthe concentration of antimony in the substrate; Ncm3- the effective density of States, given to the top level of silver; 3=NAg/NSbthe degree of compensation of impurities in the substrate, gfthe photoionization cross section of the upper level of silver; (g recombination coefficient; I is the radiation intensity, mothe concentration of electrons at the top level of silver.
< / BR>where 10-12cm-3with-1; gf=10-17cm2; I 51012Kwan/cm2s; V 1B; e 16th cent to 8.85 10-14FSM-1; L 310-2seeAs can be seen from table 2, the increase of the photocurrent can be obtained on the substrate with precompetitive with the stationary regime. The variation of the degree of compensation on the substrate is mainly defined by the distribution of antimony in Germany when the radial distribution 2 (3 1,02 1,0), which leads to a change of photosensitivity in a stationary mode at 40Kn1/n34,1 1012/8 1075 104again, in the pulse mode, this ratio will 4,11012/8107125= 4102times, i.e., the photocurrent increases 5104/4102< / BR>102time.When allocating 0.5 % of n1/n2= 4,11012/3 108103using the pulse mode 4,11012/310831=30, i.e., the photocurrent increases 30 times.Since the increase of the photocurrent in precommissioning the portions of the substrate is greater than in areas with exact compensation, when the pulse mode of the survey reduced the heterogeneity of the distribution of photosensitivity on the working field of the FPU. When the degree of compensation 3 = 1,0; 3 = 1,02 variation of the photocurrent is 5 104once in stationary mode, pulse mode 4 102times.Thus, when creating the transition region 2 with a thickness there is a separation of the functions of an injecting contact to offset the substrate into two: the first function of the ohmic contact performs the contact metal and poverhnosti volume of the substrate. The width of the area 2 should be L, n+-n junction at the exact compensation of impurities. This allows to obtain technologically reproducible contact, reducing the heterogeneity of the distribution of photosensitivity, increase the photosensitivity in the pulse mode survey at low temperatures, eliminates the effect of surface on an injecting contact.2. Compared with gold, deposited on a substrate was obtained more stable ohmic contact compensated Germany.In table. 3 presents FPU with different metal films. 1. Photodetector for the infrared region of the spectrum containing a substrate of semiconductor doped shallow donor impurity and accurately compensated deep multi-charged acceptor impurity, creating a double negatively charged levels, on both sides of which a conductive bus consisting of created in the substrate contact layer enriched with specially designed small impurity of the same conductivity type as the substrate, and the applied metal film, creating an electrical contact, wherein the contact layer comprises a first region in contact with meth what/SUB>,
where D is the diffusion coefficient of majority carriers;
Lthe WPPTthe diffusion length;
the coefficient of recombination of carriers;
L1the thickness of the first region and the second region with an impurity concentration of 1 to 2% above the concentration of the shallow donor impurity of the substrate, and their thickness are correlated as follows:
< / BR>where L2the thickness of the second region;
Dv the height of the potential barrier of the n+n - or p+p - transition;
e the electron charge;
Ntthe concentration of traps in the levels of the acceptor impurity in the exact compensation of impurities equal to the dark concentration of carriers;
Emaxthe maximum field of the space charge region of the contact metal substrate;
vothe height of the potential barrier of the contact metal substrate.2. The device under item 1, characterized in that the metal film is Nickel.
FIELD: spectral-analytical, pyrometric and thermal-vision equipment.
SUBSTANCE: emitter has electro-luminescent diode of gallium arsenide, generating primary emission in wave length range 0,8-0,9 mcm, and also poly-crystal layer of lead selenide, absorbing primary emission and secondarily emitting in wave length range 2-5 mcm, and lead selenide includes additionally: admixture, directionally changing emission maximum wave length position as well as time of increase and decrease of emission pulse, and admixture, increasing power of emission. Photo-element includes lead selenide layer on dielectric substrate with potential barrier formed therein, and includes admixtures, analogical to those added to lead selenide of emitter. Optron uses emitter and photo-elements. Concentration of addition of cadmium selenide in poly-crystal layer of emitter is 3,5-4,5 times greater, than in photo-element. Open optical channel of Optron is best made with possible filling by gas or liquid, and for optimal synchronization and compactness emitter and/or photo-element can be improved by narrowband optical interference filters.
EFFECT: higher efficiency, broader functional capabilities.
3 cl, 3 tbl, 6 dwg
FIELD: fiber-optic communications, data protection, telecommunications, large-scale integrated circuit diagnosing and testing, single molecule spectrometry, astronomy, and medicine.
SUBSTANCE: proposed device has substrate carrying contact pads, One strip is made of superconductor in the form of meander and its ends are connected to contact pads. Other, additional, semiconductor strip is connected in parallel with above-mentioned strip made in the form of meander. Additional strip is made of superconductor whose kinetic inductance is lower than that of strip made in the form of meander.
EFFECT: enhanced speed, sensitivity, and bandwidth of detector.
9 cl, 2 dwg
FIELD: infrared detectors.
SUBSTANCE: proposed photodiode infrared detector has semiconductor substrate translucent for spectral photodetection region rays and semiconductor graded band-gap structure disposed on substrate;. graded band-gap structure has following layers disposed one on top of other on substrate end. Highly conductive layer of one polarity of conductivity and fixed forbidden gap width produced by heavy doping; layer of other polarity of conductivity and other forbidden gap width in the form of little hump whose value gradually rises from that corresponding to forbidden gap width of preceding layer and then, with smoother decrease to value corresponding to forbidden gap width of preceding layer or smaller. Working layer of same polarity of conductivity as that of preceding layer and fixed forbidden gap width equal to degree of final decrease in forbidden gap width of preceding layer and also equal to forbidden gap width in first of mentioned layer or smaller. Working layer is provided with p-n junction exposed at its surface. Layer disposed on working-layer p-n junction and having gradually increasing forbidden gap width to value corresponding to working layer and polarity of conductivity reverse to that of working layer.
EFFECT: maximized current-power sensitivity, enhanced maximal photodetection frequency, uniform parameters with respect to surface area.
12 cl, 2 dwg
FIELD: power engineering.
SUBSTANCE: invention is used in optical data acquisition systems with high registration efficiency of light radiation by means of avalanche photodiodes with Geiger discharge quenching circuit. Into solid Geiger detector with active restorer, which includes avalanche photodiode the anode whereof is connected to the shift voltage bus and cathode is connected to the first electrode of damping resistor, and a switching restoring transistor, there introduced is the additional damping resistor. The first electrode of the additional damping resistor is connected to the second electrode of damping resistor and to the sink of switching restoring transistor the gate of which is connected to the first electrode of damping resistor, and sink is connected to the second electrode of the additional damping resistor and detector power bus. Switching restoring transistor is made in the form of transistor with a built-in channel.
EFFECT: increasing dynamic range of detector as well as increasing registration efficiency.
FIELD: physics, photography.
SUBSTANCE: invention can be used, for instance in wide-field heat direction finding or thermal imaging devices working in two spectrum regions. The dual spectrum photodetector consists of p modules, each having photosensitive elements, two multiple-element photosensitive lines, a multiplexer and a base. The first multiple-element line is sensitive in one spectrum region and lies on the substrate of the first photosensitive element and the second multiple-element line is sensitive in the other spectrum region and lies on the substrate of the second photosensitive element. In one version first photosensitive elements are trapezium shaped, which enables to arrange the modules such that photosensitive structures, each formed by the lines which are sensitive in one spectrum region, have the shape of regular polygons. In the other version second photosensitive elements are rectangular shaped, which enables arrangement of the modules such that photosensitive structures are in form of a line.
EFFECT: design of dual spectrum large-format multiple-module photosensitive structures of different configurations.
8 cl, 6 dwg
FIELD: physics, semiconductors.
SUBSTANCE: invention relates to microelectronics and can be used in designing semiconductor ultraviolet radiation sensors. A semiconductor UV radiation sensor has a substrate on which there are series-arranged wiring layer made from TiN, a photosensitive AlN layer, and an electrode system which includes a platinum rectifying electrode which is semi-transparent in the C-region of UV radiation, connected to the AlN layer to form a Schottky contact, first and second leads for connecting to an external measuring circuit, where the first lead is connected to the wiring layer and the second to the rectifying electrode. The method of making a semiconductor UV radiation sensor involves successive deposition of a wiring TiN layer and a photosensitive AlN layer onto a substrate through reactive magnetron sputtering on a general processing unit in a nitrogen-containing gas medium with subsequent formation of a platinum rectifying electrode which is semitransparent in the C-region of UV radiation, connected to the photosensitive AlN layer to form a Schottky contact, and leads for connecting the rectifying electrode and the wiring layer to an external measuring circuit. The wiring and photosensitive layers are deposited continuously without allowing cooling down of the substrate. The platinum rectifying electrode is made through three-electrode ion-plasma sputtering of a platinum target at pressure of 0.5-0.6 Pa for 4-6 minutes, target potential of 0.45-0.55 kV and anode current of 0.8+1.2 A. Sensitivity of the end product is equal to 65-72 mA/W.
EFFECT: increased sensitivity of the end product.
2 cl, 2 dwg, 1 tbl
SUBSTANCE: infrared radiation sensitive structure having a substrate whose top layer is made from CdTe, a 10 mcm thick working detector layer made from Hg1-xCdxTe, where x=xd=0.2-0.3, a 0.1-0.2 mcm thick insulating layer made from CdTe, and a top conducting layer with thickness of approximately 0.5 mcm also has a 0.5-6.0 mcm thick lower variband layer between the substrate and the detector layer, where the said variband layer is made from Hg1-xCdxTe, where the value of x gradually falls from a value in the range of 1-(xd+0.1) to a value xd, between the working detector layer and the insulating layer, a top variband layer with thickness of 0.03-1.00 mcm made from Hg1-xCdxTe where the value of x gradually increases from a value xd to a value in the range of 1-(xd+0.1), and dielectric layers between the insulating layer and the top conducting layer. Disclosed also is a method of making the said structure.
EFFECT: possibility of making a highly stable infrared sensitive structure with broad functional capabilities.
12 cl, 1 dwg
SUBSTANCE: method of reducing spectral density of photodiode diffusion current fluctuation in high frequency range involves applying reverse bias V across a p-n junction with a short base and a blocking contact to the base, said reverse bias satisfying the conditions 3kT < q|V| < Vb,t and 3kt < q|V| < Vb,a, where: k is Boltzmann constant; T is temperature; q is electron charge; Vb,t is tunnel breakdown voltage; Vb,a is avalanche breakdown voltage.
EFFECT: disclosed method enables to increase the signal-to-noise ratio of the photodiode in the high frequency range by reducing spectral range of diffusion current fluctuation.
SUBSTANCE: high signal-to-noise (S/N) ratio infrared photodiode has a heavily doped layer (1) of a main p-n junction, a heavily doped layer (2) of an additional p-n junction, a padded base (3) for the main and additional p-n junctions and a substrate (5). The common base (3) has a space-charge region (4) for the main p-n junction. An ohmic contact (6, 7, 8) is formed for each of the layers of the structure. The total thickness of the heavily doped layer of the main p-n junction and the space-charge region of the main p-n junction lying in the common base satisfies a condition defined by a mathematical expression. To increase the S/N ratio in the infrared photodiode, diffusion current of the additional p-n junction and the sum of the diffusion current and photocurrent of the main p-n junction are recorded, and the diffusion current of the additional p-n junction is then used for correlation processing of the signal and noise of the main p-n junction. S/N ratio in the infrared photodiode is increased by using diffusion current of the additional p-n junction, whose noise is correlated with noise of the diffusion current of the main (infrared radiation detecting) p-n junction, for correlation processing of the signal and noise of the main p-n junction.
EFFECT: high signal-to-noise ratio of the infrared photodiode.
2 cl, 2 dwg
SUBSTANCE: inventions can be used in threshold photodetectors for detecting weak electromagnetic radiation in the infrared range. The high signal-to-noise ratio infrared photodiode has a heavily doped layer adjacent to a substrate which is transparent for infrared radiation, whose thickness l1 satisfies the condition: and a weakly doped layer of another conductivity type (base), whose thickness d satisfies the condition d<L. Ohmic contacts are formed along two opposite sides of the periphery of the weakly doped layer. To increase the signal-to-noise ratio in the infrared photodiode, the sum of diffusion current and photocurrent of the p-n junction, and current of the longitudinal conductance of the base, which flows between ohmic contacts formed along two opposite sides of the periphery of the weakly doped layer, is determined, while applying a small voltage across said contacts, which satisfies a given condition.
EFFECT: invention increases the signal-to-noise ratio of the infrared photodiode by using current of longitudinal conductance of the base, whose noise is correlated with noise of the diffusion current of the p-n junction, for correlated processing of the signal and the noise of the p-n junction which detects infrared radiation.
2 cl, 3 dwg