Semiconductor heterostructure

FIELD: physics.

SUBSTANCE: stressed semiconductor heterostructure (10) has an injection region which includes a first emitter layer (11) and a second emitter layer (12), as well as light-generating layer (13) between the emitter layers (11, 12). Between the light-generating layer (13) and the second emitter layer (12) there is an electron capture region (14) which has a capturing layer (16) next to the second emitter layer and a boundary layer (15) next to the said electron capture layer. Concentration of electrons in the second emitter layer (12) is equal to the product of concentration holes in the first emitter layer (11), the ratio of the diffusion coefficient for holes in the second emitter layer (12) to the diffusion coefficient for electrons in the first emitter layer (11) and the ratio of the diffusion length for electrons in the first emitter layer (11) and to diffusion length for holes in the second emitter layer (12).

EFFECT: invention enables design of a stressed semiconductor heterostructure with high apparent power of light generation.

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The technical FIELD

The present invention relates to semiconductor heterostructures for light-emitting devices, in particular the structure formed from semiconductor materials with the mismatch of the crystal lattice. This heterostructure includes injection region, consisting of two emitters, the layer generating light and a region of electron capture. In particular, the heterostructure can be made of pyroelectric materials, such as nitrides of group III and their alloys. In addition, the heterostructure can be made of nitrogen-containing arsenides and phosphides of metals of group III.

The LEVEL of TECHNOLOGY

External quantum efficiency of a light emitting diode, below called led, can be defined as:

ηt=γ·ηRAA·ηint·ηout,

where γ is the coefficient of injection, ηcap- capture efficiency of charge carriers in the region generating light, ηintthe radiation efficiency due to radiative recombination of charge carriers in the generation of light, ηoutthe efficiency of extraction of light. The maximum efficiency of the led is obtained by the maximum values of all parameters. The first three coefficients are interrelated, and therefore in the design of the led is useful to consider them in sosaku the property.

The first factor to consider is the efficiency of capture of charge carriers in the region generating light. In case of mismatch of the crystal lattice between the layers of the device layer thickness, in which recombination of electrons and holes must be sufficiently low to preserve the quality of the material and avoid the stress relaxation due to the formation of dislocations. However, when reducing the thickness of the capture of charge carriers in the layer generating light is significantly reduced. This grip can be described by the ratio

where q+and q-the flow of charge carriers within the layer generating light and passing through it, n is the concentration of charge carriers in the emitter, d - width of the narrow-gap layer generating light and τ is the time of capture of charge carriers, usually determined by the interaction of electrons with optical phonons. This equation shows that the captured portion of the flow of the carriers decreases with decreasing thickness of the layer generating light and inversely proportional to the time of capture of charge carriers. When the fixed width of the layer generating light capture of charge carriers has a lower efficiency for electrons due to the smaller effective mass of the electrons and, hence, more time τ the relaxation energy is I.

Another essential mechanism that reduces the capture of charge carriers in the narrow gap region, is partially reflected electron or hole wave from this area. Therefore, the probability of charge carrier in the narrow gap region decreases, which leads to less effective communication with localized States in narrow-gap layer and increase the time τ of the capture of charge carriers. As a result, the efficiency of the capture device is reduced and the maximum of efficiency dependence of ηextfrom the injection current is is significantly below the typical operating current for the device. To solve this problem it was suggested many designs. One solution is to use an extra wide gap layer in the generation of light from the side of the injection holes to prevent the escape of electrons outside this area. This decision was adapted for the case of light-emitting devices based on nitrides Nagahama (Nagahama) and the other in U.S. patent No. 6677619 and existing links. However, the presence of this barrier increases the reflection of electrons and holes, which makes this solution is not optimal.

To prevent charge carriers from the region of generation of light Nakamura (Nakamura) and others in the application for U.S. patent No. 2004/0101012 proposed to create two barriers is and on both sides of the generation of light. Due to the fact that this solution is essentially leads to a strong reflection of charge carriers from the barriers, the authors proposed to make these barriers are more subtle, to increase the probability of tunneling through them charge carriers. However, one drawback of this solution is that the tunneling of charge carriers in this case is not resonant, and therefore, when any reasonable thickness of barriers reflection of charge carriers from barriers significantly reduces the efficiency of capture of charge carriers in the region generating light. Wang (Wang), and others in the United Kingdom patent No. 2352326 revealed the design of the CART, in which electrons are collected in the preliminary tank in the field structure with n-type conductance, where they are resonant tunneling in the region generating light. For the efficient collection of charge carriers tank must be sufficiently thick. In fact, it is difficult to produce a thick, high-quality layer based on semiconductor materials with the mismatch of the crystal lattice.

The second factor considered is the ratio of injection. Because the light is generated in a thin layer generating light, which is located near the p-n junction, it is desirable in this transition to ensure the maximum rate of injection. The usual solution is that Maxim is) possible to legitamate emitters without deterioration of the material. However, for materials in which the concentration of the active centers of doping in one of the emitters is limited to fundamental material properties, excessive alloying of the other emitter upsets the balance of currents injection of electrons and holes in the layer generating light that reduces the rate of injection.

The third factor considered is the efficiency of radiation. If the device is made of a pyroelectric material in the structure is the spontaneous polarization and piezoresistive caused caused by deformation, resulting in a built-in electric field, which leads to a spatial separation of electrons and holes in the generation of light. In the radiative recombination can only go by indirect optical transitions. This indirect recombination leads to the decrease of the quantum yield of radiation in the device. This phenomenon is discussed in many publications, including works by Bernardini et al, "Spontaneous polarization and piezoelectric constants of III-V nitrides", American Physical Society Journal, Physics Review B, Vol. 56, No. 16, 1997, pages R10024-R 10027; Takeuchi et al, "Quantum-Confined Stark Effect due to Piezoelectric Fields in GalnN Strained Quantum Wells", Japanese Journal of Applied Physics, Vol. 36, Part 2, No. 4, 1997, pages L382-L385; and Ambacher et al., "Pyroelectric properties of Al(In)GaN/GaN hetero-and quantum well structures", Journal of Physics: Condensed Matter, Vol. 14, 2002, pages 3399-3434. To some extent the impact of the built floor the polarization can be reduced by using very thin layers generating light. However, as noted above, such a small thickness leads to inefficient capture of charge carriers. In addition, the width of the layers generating light may become comparable with the fluctuations of the thickness. These fluctuations can lead to the formation of "holes" in the layer generating light, which act as centers of nonradiative recombination, thus further reducing the efficiency of the device. And finally, due to the built-in polarization electric field limits the effectiveness of radiation and capture rate. In U.S. patent No. 6515313 revealed several ways of reducing the influence charges, induced polarization: selective doping designed to deliver such charge impurities, which could compensate for the charge-induced polarization; meningeal layers with varying composition; an active region with a variable or a mixed composition; inverted polarization. Another solution is to use as materials for the generation of light semiconductor structures with coherent lattice. However, in the pyroelectric material has spontaneous polarization, which is different from zero even in loose layers or layers with a matched crystal lattice. For example, the magnitude of spontaneous polarization in nitrides meta the crystals of group III to the same value, due to the piezoelectric effect. Some other ways to reduce the piezoelectric polarization are disclosed in U.S. patent No. 6569704 and No. 6630692.

As follows from the above, the development of highly efficient light-emitting structure will be more efficient sequential solution preferably all of these issues.

The PURPOSE of the INVENTION

The purpose of the invention is to eliminate the above disadvantages.

One of the specific objectives of the present invention is to provide a new type strained semiconductor heterostructures with high total power generation of light, and this heterostructure is made, for example, from the pyroelectric semiconductor materials, such as nitrides of III group metals and their alloys, or of the nitrogen of arsenides and phosphides of metals of group III.

In addition, the present invention is to provide a new type of light-emitting diode that uses a strained semiconductor heterostructure.

The INVENTION

Strained semiconductor heterostructure made according to the present invention, is characterized by the features disclosed in claim 1 of the claims.

According to the present invention a semiconductor heterostructure contains: the injection region is, including a first emitter layer, having conductivity of p-type, and the second emitter layer, having conductivity of n-type layer generating light, located between the emitter layers and the area of electron capture, which is located between the second emitter layer and a layer generating light. The area of electron capture layer includes capture, located next to the second emitter layer, and a restrictive layer adjacent to the layer capture. In the present description, the term "strained heterostructure", usually refers to the heterostructure, consisting of separate layers, where the in-plane lattice constant of at least one layer differs from its equilibrium value, and the term "layer"generally refers to a single crystal epitaxial layer. The area of electron capture is designed to provide relaxation energy of the electrons and reduce the likelihood of migration of electrons outside layer generating light. The width of the bandgap in the layer generating light is less than the width of the forbidden band in the emitter layers and the restrictive layer. The width of the gap layer capture is less than the width of the forbidden zone in a restrictive layer. In addition, the energy position of the lowest energy levels for electrons in a layer of capture is higher than in the layer generating light.

According to the SNO present invention, the concentration of electrons in the second emitter layer is chosen so that that is equal to the product of: (1) the concentration of holes in the first emitter layer, (2) the relationship of the diffusion coefficient for holes in the second emitter layer and the diffusion coefficient for electrons in the first emitter layer and (3) the relationship of the diffusion length for electrons in the first emitter layer and the diffusion length for holes in the second emitter layer. Under this condition, the concentration of holes and electrons in the injection region are equal and in balance injection currents in the layer generating light, which leads to increasing the rate of injection. Below summarizes theory, which lies at the basis of the specified selection electron concentration.

Because the light is generated in a thin layer generating light, which is located near a boundary between the p - and n-regions, it is desirable to provide at this boundary the maximum rate of injection. Within the model Shockley-Neuss-Sa (Shockley-Noyce-Sah), which involves the recombination in the field of space charge and corresponds to the typical operating currents of the led, the recombination rate is proportional to the product of the concentrations of electrons and holes, but not to the product of the concentrations of the major charge carriers in the emitter. Specialists in this field it is clear that the reason is that in the p-n junction, biased in the forward direction, the concentration of injectionand the x media depend on the concentration of minority charge carriers and the applied voltage, but not from the concentrations of the major charge carriers. Thus, the ratio of the maximum injection under the condition that the current density of electrons and holes are equal at the interface of the p - and n-regions, because the full current density is equal to the sum of these two current densities and constant throughout the structure. For a given concentration of ppholes in the emitter region of the p-type equality density currents of electrons and holes specifies the condition for the concentration of nnelectrons in the emitter region of n-type in the form:

where Dpand Dnthe diffusion coefficients, a Lpand Lnthe diffusion length for minority carriers in the emitter n-type and p-type conductivity, respectively.

Used in the present description the terms "diffusion coefficient and diffusion length can be found, for example, in the book N.W. Ashcroft, N.D. Mermin "Solid State Physics", Saunders College Publishing, 1976, pages 602-604. Professionals in this field are well known way of creating the required concentrations of electrons and holes in the layers. For the selected group of semiconductor materials (for example, nitrides of metals of group III) typically, the concentration of electrons in the emitter region of n-type several times higher than the concentration of holes in the emitter region of p-type. In this case, the current injection of electrons in the space charge region is higher than the OK injection holes, which leads to reduction of the rate of injection compared with the maximum possible efficiency. In this case, the most obvious solution to increase the efficiency of generation of light is to increase the concentration of holes in the emitter region of p-type. However, doping the semiconductor with the aim of increasing the concentration of holes may be limited by fundamental characteristics of the material. In a heterostructure made under this variant implementation of the present invention, the balance between the currents injection of electrons and holes is due to the special design of the emitter region of n-type in the p-n junction. In this case, the emitter region is n-type with a moderate doping level is placed between the layer of n-contact and the area of electron capture.

In one embodiment of the present invention strained semiconductor heterostructure made of pyroelectric semiconductor material, and a layer generating light has such a composition and thickness that the electric field due to spontaneous pyroelectric polarization, has a magnitude and direction that is essentially equal and opposite direction to the piezoelectric field due to mechanical stress. In the present description uses the terms "pyro polarizes the I and piezoelectric polarization, disclosed, for example, in the book N.W. Ashcroft, N.D. Mermin "Solid State Physics", Saunders College Publishing, 1976, page 555. The idea is to provide a fixed mismatch of the crystal lattice between the emitter layer and the layer generating light to an electric field Epiezodue to the superposition of the charges of the piezoelectric polarization compensated field Espdue to the superposition of spontaneous polarization charges:

Esp≈Epiezo

In this case, the charge carriers in the layer generating light are not separated spatially, and this leads to increased emission efficiency. For example, in the layer AllnGaN piezoelectric and spontaneous polarization can be directed in opposite directions depending on the composition. Therefore, the material layer for generating light, and adjacent layers are chosen so that to provide the size of the integrated field-induced spontaneous (pyroelectric) polarization equal to the value of the built-in piezoelectric fields, and the direction of the built-field-induced spontaneous (pyroelectric) polarization, opposite the direction of the built-in piezoelectric fields. Materials for pyroelectric layer can be, for example, nitrides of metals of group III and their alloys. At least one of the emitter layer may include AlxGa 1-xN, where 0≤x≤1. At least one of the following layers: layer generating light, a restrictive layer and a layer of grip may include AlxInyGa1-x-yN, where 0≤x≤1, 0≤y≤1, 0≤x+y≤1.

Preferred neirolepticakimi materials for the structure proposed in the present invention are nitrogen-containing arsenides and phosphides of metals of group III. For example, at least one of the following layers: an emitter layer, a layer generating light, a restrictive layer and a layer of grip may include AlxInyGa1-x-yASaNbP1-a-bwhere 0≤x≤1; 0≤y≤1; 0≤x+y≤1; 0≤a≤1; 0<b≤0,1; 0≤a+b≤1.

Another preferred embodiment of the present invention to enhance the relaxation of charge carriers, if desired, can be implemented by embedding in the structure of additional layers. According to this variant implementation of the present invention, at least one pair of wide-gap and narrow-gap layer placed between the restrictive layer and a layer generating light, and a layer located next to the restrictive layer is a narrow-gap layer. The width of the forbidden zone in a liquid layers is greater than in narrow-gap layers and the layer generating light. The composition and thickness of the narrow and wide bandgap layers are selected so that the lowest energy levels for electrons in l the BOM narrow-gap layer lying above than the layer generating light, lower than in layer capture, and lower than in narrow-gap layers located between the observed narrow-gap layer and the restrictive layer. In addition, these compositions and thickness selected so that the energy difference between the lowest local energy levels for electrons in a layer of grip and a similar level in narrow-gap layer located next to restrictive layer was equal to the energy of the optical phonon. The term "energy optical phonon" refers to the energy of the optical branches of lattice vibrations near zero wave vector. Such alignment with the energy of the phonon can be performed for each pair of adjacent narrow gap layers. The relaxation energy in such a structure occurs through a sequence of processes involving phonons and, therefore, will increase.

This principle agreement with the phonon can also be used between the bottom of the conduction band of the second emitter layer and a layer of capture. In other words, the width and the material layer capture and restrictive layer can be selected so that the energy difference between the one of the local energy levels for electrons in a layer of grip and the bottom of the conduction of the second emitter layer was equal to the energy of the optical phonon. Due to the interaction with prodelin the mi optical (LO, longitudinal optical) phonon capture of electrons in narrow-gap layer capture will be more intense in comparison with capture on an arbitrarily set level, as in the above situation, the momentum transferred to the phonon in the transition of an electron with energy loss will be close to zero. Relaxation is mainly due to spontaneous emission of optical phonons at moderate temperatures. The reverse process of thermal emission of charge carriers from the narrow-gap layer capture in the emitter layer occurs due to the absorption of phonons, and therefore is limited by the factor of Nq/(1+Nq), where Nqthe number of phonons is given by the Planck distribution. For example, in the case of nitrides of metals of group III of the energy of an optical phonon is equal to approximately 100 MeV; therefore, at room temperature the rate of emission will be less than with a capture rate of approximately 40 times. Further relaxation of the energy of the charge carriers occurs or through lower energy levels within a layer of capture, and then in the adjacent narrow-gap layer generating light, or directly in the layer generating light. Thus, according to the present invention, a layer of grip has a much higher efficiency of electron capture in comparison with known structures.

In addition, the structure, aderasa the specified additional wide-gap and narrow-gap layers, can be made of pyroelectric materials. In this case, at least one of the emitter layer may include AlxGa1-xN, where 0≤x≤1. At least one of the following layers: layer generating light, a restrictive layer and a layer of grip may include AlxInyGa1-x-yN, where 0≤x≤1, 0≤y≤1, 0≤x+y≤1. Additional layers may include, for example, alternating wide bandgap layers of AlmiInniGa1-mi-niN and the narrow gap layers of AlkiInliGa1-ki-liN, where i enumerates pairs, 0≤mi≤1, 0≤ni≤1, 0≤mi+ni≤1, 0≤ki≤1, 0≤li≤1, 0≤ki+li≤1.

In the structures according to the present invention, containing layers of the above pyroelectric materials, you can add additional region of n-type low resistivity, next to the specified second emitter layer, a region of low resistivity includes a superlattice for spreading the transverse currents generated from a variety of alternating pairs of layers of AlxGa1-xN and AlyGa1-yN, where 0≤x≤1 and 0≤y≤1.

In nejrologicheskoj structure with additional wide-gap and narrow-gap layers in the area of capture at least one of the following layers: an emitter layer, a layer generating light, a restrictive layer and a layer of grip may include AlxInyGa1-x-yASaN bP1-a-bwhere 0≤x≤1; 0≤y≤1; 0≤x+y≤1; 0≤a≤1; 0<b≤0,1; 0≤a+b≤1. Additional layers may include, for example, alternating wide bandgap layers of AlmiInniGa1-mi-niASpiNqiP1-pi-qiand the narrow gap layers of AlkiInliGa1-ki-liASriNgiP1-ri-giwhere i enumerates pairs, 0≤mi≤1; 0≤ni≤1; 0≤mi+ni≤1; 0≤pi≤1; 0<gi≤0,1; 0≤pi+qi≤1; 0≤ki≤1; 0≤li≤1; 0≤ki+li≤1; 0≤ri≤1; 0<si≤0,1; 0≤ri+si≤1.

Light-emitting diode (led)made according to the present invention, is distinguished by the characteristics stated in claim 11 claims. Light-emitting diode contains a strained semiconductor heterostructure described above. Thus, it has significantly increased the efficiency of light emission in comparison with the known devices. The entire device is designed to provide high efficiency generation of light at high current densities. All described aspects of the preferred embodiments of the present invention, i.e. selecting the concentration of electrons, the compensation of the piezoelectric field, the presence of additional layers in the area of capture and control the energy of the phonon, can be combined to achieve optimal performance of the device, it is preferable to optimize them simultaneously. For example, the composition of the layer generating light, narrow-gap layer in the area of electron capture and emitter layers can be chosen so as to provide (a) a flat profile zones in the layer generating light, (b) the energy of the transition is equal to the energy of the optical phonon, (in) the desired wavelength. The doping levels are determined on the basis of balance of current injection, as described above.

In addition, light-emitting diode (led)made according to the present invention, is distinguished by the features indicated in item 12 of the claims. Light-emitting diode includes a semiconductor heterostructure according to claim 4 or 10, which was described above. According to the present invention this heterostructure grown on a substrate of GaP, GaAs or InP. In addition, the emitter layers consistent with false on the lattice parameters. In other words, the lattice emitter layer essentially coincides with the period of the crystal lattice of the substrate.

So, in comparison with the known technical solution achieved several advantages. In particular, the area of capture of electrons with the above-described tuning the energy of the phonon provides effective relaxation of the electron energy and suppresses the release of electrons outside layer generating light. Another advantage is that the concentration of holes and electrons in the field of injection can be chosen so as to ensure the balance of injection currents in the layer generac and light. Another advantage is that, if heterostructure made of pyroelectric semiconductor material, the layer generating light may have a structure in which the electric field in this layer is approximately equal to zero. In total external quantum efficiency of light-emitting diode that uses a heterostructure according to the present invention, will be significantly increased. The entire device is designed to provide high efficiency of light generation in high density operating currents.

The previous description, as well as other advantages of the present invention and methods of its implementation are specified in the following detailed description with reference to accompanying drawings.

LIST of DRAWINGS

Below the invention will be described in detail with reference to accompanying drawings, where

1 schematically shows a cross-section showing an example of the semiconductor heterostructure according to the present invention;

figure 2 shows the band structure of the layer generating light and a capture area for a semiconductor heterostructure, shown in figure 1;

figure 3 shows the band structure for semiconductor heterostructures with a pair of wide-gap and narrow-gap layers located between the restrictive layer and a layer generac and light according to the present invention;

on figa illustrated semiconductor heterostructure-based p-n junction used in light-emitting diodes, for the case when the concentration of electrons in the emitter region of n-type is greater than the concentration of holes in the emitter region p-type, fig.4b illustrates the distribution of the concentration of electrons and holes in the same structure, as in figure 4 to illustrate the distribution of the density of electron and hole currents in the same structure;

on figa illustrated semiconductor heterostructure-based p-n junction with the balance of injection into the light-emitting diodes according to the present invention, fig.5b illustrates the distribution of the concentration of electrons and holes in this structure, and figs illustrates the density distribution of electron and hole currents in the same structure; and

figure 6 schematically shows a cross section of a semiconductor heterostructure light-emitting diodes made of nitrides of group III according to the present invention.

DETAILED description of the INVENTION

1 schematically shows a cross section of semiconductor heterostructures. The heterostructure 10 includes injection region consisting of the first emitter layer 11 and the second emitter layer 12, a layer 13 of generating light and an area 14 of electron capture, comprising the C layer capture and restrictive layer.

Figure 2 is a schematic representation of the band structure of heterostructures shown in figure 1. The grip area is a narrow-gap layer adjacent to the second emitter layer. Wide bandgap layer between the layer of the capture layer and generating light forms a restrictive layer. The thickness and composition of layer's capture and the restrictive layer is chosen so that the energy difference between the one of the local energy levels of the electron in the layer of the grip and the bottom of the conduction band in the emitter of electrons was equal to the energy of the optical phonon. The capture of electrons in narrow-gap layer capture is due to the interaction with longitudinal optical (LO) phonon, which is marked with the number 1. As a result, the capture efficiency increases compared with capture on an arbitrarily set level. Further relaxation energy, denoted by the position 2, the charge carrier comes first at lower energy levels within the same narrow-gap layer capture, and then in the adjacent narrow-gap layer generating light.

Figure 3 schematically shows the band diagram of the heterostructure, in which between the restrictive layer and a layer generating light added one pair of wide-gap and narrow-gap layers. The composition and thickness entered layers is chosen so that the lowest energy levels for electrons in narrow-gap layer l is said above, than the corresponding energy levels in the layer generating light, and is lower than the corresponding energy levels in the layer capture. In addition, the options embedded layers is chosen so that the energy difference between the lowest energy levels in the adjacent layer of grip and narrow-gap layer was equal to the energy of the optical phonon. The capture of electrons in narrow-gap layer capture occurs, as shown in figure 2, due to the interaction with longitudinal optical (LO) phonon, which is marked with the number 1. The relaxation energy in such a structure occurs as a series of processes indicated by the positions 2 and 3, the latter process is part of the phonon. Due to the additional step 3 involving phonon relaxation energy is even stronger than in the case without additional layers.

Comparing figure 4 and figure 5 allows you understand the impact of the selection of the electron density according to the present invention. In the structure shown in figure 5, the concentration of electrons satisfies the condition:

where Dpand Dnthe diffusion coefficients, a Lpand Lnthe diffusion length for minority carriers in the emitter with a conductivity of n-type and p-type, respectively. In this case, the current density of electrons and holes at the boundary of the p-n junction are equal, and thus the m the ratio of the maximum injection, unlike the case shown in figure 4, in which the concentration of electrons in the emitter region of n-type is greater than the concentration of holes in the emitter region of p-type.

Figure 6 shows an example of semiconductor heterostructures for light-emitting diodes made of nitrides of group III according to the present invention. The heterostructure 10 includes injection region consisting of the first emitter layer 11, which is made of GaN with a conductivity of p-type, the concentration of holes 5×1017cm-3and a thickness of 0.5 μm, and the second emitter layer 12, which is made of GaN with n-type conductance, electron concentration of 1×1018cm-3and a thickness of 0.5 μm; a layer 13 of the generation of light made of unalloyed Al0.04In0.22Ga0.74N thickness of 0.003 μm; the area of capture of electrons consists of a restrictive layer 15 made of non-alloy Al0.2In0.05Ga0.75N thickness 0,0015 μm, and a layer 16 of electron capture from unalloyed In0.06Ga0.94N thickness 0,006 μm; and the region 17 with low specific conductivity made of GaN with n-type conductance, electron concentration of 5×1018cm-3and a thickness of 2 μm.

The invention is not limited to the examples discussed above, and numerous modifications are possible within the forms of the crystals of the invention.

1. Strained semiconductor heterostructure (10)containing:
injection area comprising a first emitter layer (11)having conductivity is p-type, and the second emitter layer (12)having conductivity of n-type,
layer (13) of the generation of light, located between the first emitter layer (11) and the second emitter layer (12), and the width of the forbidden zone of the specified layer generating light is less than the width of the forbidden band of the first and second emitter layers;
region (14) capture of electrons located between the layer (13) generating light and a second emitter layer (12) and containing layer (16) capture, located next to the second emitter layer and the restrictive layer (15), located next to the specified layer of electron capture, and the width of the forbidden zone specified restrictive layer is greater than the width of the gap layer generating light, the width of the forbidden zone of the specified layer capture is less than the width of the forbidden zone of the restrictive layer, and the lowest energy level for electrons in the layer capture lies above the corresponding level in the layer generation light, characterized in that the concentration of electrons in the second emitter layer (12) is chosen equal to the product of: the concentration of holes in the first emitter layer (11), the relationship of the diffusion coefficient for holes in the second emitter layer (12) and CoE is ficient diffusion for electrons in the first emitter layer (11) and the relationship of the diffusion length for electrons in the first emitter layer (11) and the diffusion length for holes in the second emitter layer (12).

2. Strained semiconductor heterostructure (10) according to claim 1, characterized in that it is formed from pyroelectric semiconductor material, and the thickness and the material layer (13) of the generation of light is selected so that the built-in electric field due to spontaneous pyroelectric polarization was essentially equal in magnitude and substantially opposite in direction to the corresponding built-in piezoelectric field.

3. Strained semiconductor heterostructure (10) according to claim 2, characterized in that the at least one of the following conditions:
said first emitter layer (11) includes Alx1Ga1-x1N, where 0≤x1≤1;
the specified second emitter layer (12) includes Alx2Ga1-x2N, where 0≤x2≤1;
the specified layer (13) generating light includes Alx3InU3Ga1-x3-U3N, where 0≤X3≤1, 0≤N3≤1, 0≤X3+U3≤1;
specified restrictive layer (15) comprises Alx4InA4Ga1-x4-A4N, where 0≤x4≤1; 0≤A4≤1, 0≤x4+A4≤1; and
the specified layer (16) capture includes Alx5InuGa1-x5-uN, where 0≤X5≤1, 0≤u≤1,0≤X5+u≤1.

4. Strained semiconductor heterostructure (10) according to claim 1, characterized in that the at least one of the following conditions:
said first emitter layer (11) includes Alx1InN1Ga1-x1-Y1Asa1Nb1P1-a1-b1 where 0≤x1≤1; 0≤U1≤1; 0≤x1+Y1≤1; 0≤a1≤1; 0<b1≤0.1 and 0≤a1+b1≤1;
the specified second emitter layer (12) includes Alx2InU2Ga1-x2-U2Asa2Nb2P1-a2-b2where 0≤x2≤1; 0≤U2≤1; 0≤x2+Y2≤1; 0≤A2≤1; 0<b2≤0,1; 0≤A2+b2≤1;
the specified layer (13) generating light includes Alx3InU3Ga1-x3-U3Asa3Nb3P1-a3-b3where 0≤X3≤1; 0≤U3≤1; 0≤X3+U3≤1; 0≤A3≤1; 0<b3≤0,1; 0≤A3+b3≤1;
specified restrictive layer (15) comprises Alx4InA4Ga1-x4-A4Asa4Nb4P1-a4-b4where 0≤x4≤1; 0≤A4≤1; 0≤x4+A4≤1; 0≤A4≤1; 0<b4≤0,1; 0≤A4+b4≤1;
and
the specified layer (16) capture includes Alx5InuGa1-x5-uAsa5Nb5P1-a5-b5where 0≤X5≤1; 0≤u≤1; 0≤X5+u≤1; 0≤A5≤1; 0<b5≤0,1; 0≤a5+b5≤1.

5. Strained semiconductor heterostructure (10) according to claim 1, characterized in that region (14) of the grip includes at least one pair of wide-gap and narrow-gap layer placed between restrictive layer (15) and a layer (13) generating light, and a layer located next to a restrictive layer, is one of the narrow-gap layer, the width of the gap wide gap layers is greater than the width of the gap layer generating light, the width of the narrow-bandgap layers is less than the width of the forbidden zone of wide-gap layers, and the thickness and materials of the wide-gap and narrow-gap layers selected Naini is the highest energy level for electrons in any narrow-gap layer above than the layer (13) of the generation of light is lower than that in the layer (16) capture, and lower than in narrow-gap layers located between the observed narrow-gap layer and the restrictive layer (15).

6. Strained semiconductor heterostructure (10) according to claim 5, characterized in that the thickness and materials of the wide-gap and narrow-gap layers are chosen so that the energy difference between the lowest local energy levels for electrons in narrow-gap layer located next to a restrictive layer, and the layer (16) of capture equal to the energy of the optical phonon.

7. Strained semiconductor heterostructure (10) according to claim 5 or 6, characterized in that it is formed from pyroelectric semiconductor materials, and the thickness and material of the specified layer (13) of the generation of light is selected so that the built-in electric field due to spontaneous pyroelectric polarization essentially equal in magnitude and substantially opposite in direction to the corresponding built-in piezoelectric field.

8. Strained semiconductor heterostructure (10) according to claim 7, characterized in that the at least one of the following conditions:
said first emitter layer (11) includes Alx1Ga1-x1N, where 0≤x1≤1;
the specified second emitter layer (12) includes Alx2Ga1-x2N, where 0≤x2≤1;
the specified layer (13) is enerali light includes Al X3InU3GA1-X3-U3N, where 0≤X3≤1, 0≤N3≤1, 0≤X3+U3≤1;
specified restrictive layer (15) comprises Alx4InA4Ga1-x4-A4N, where 0≤x4≤1, 0≤A4≤1, 0≤x4+A4≤1; and
the specified layer (16) capture includes Alx5InuGa1-x5-uN, where 0≤X5≤1, 0≤u≤1, 0≤X5+u≤1; and these pairs of wide-gap and narrow-gap layers include alternating wide bandgap layers of AlmiInniGa1-mi-niN and the narrow gap layers of AlkiInliGa1-ki-liN, where i enumerates pairs, 0≤mi≤1, 0≤ni≤1, 0≤mi+ni≤1, 0≤ki≤1, 0≤li≤1, 0≤ki+li≤1.

9. Strained semiconductor heterostructure (10) according to claim 3 or 8, characterized in that there is an additional region (17) low specific resistance with n-type conductance, located next to the specified second emitter layer (12) and including a superlattice for spreading cross-currents that are generated from the set of pairs of alternating layers of AlxGa1-xN and AlyGa1-yN, where 0≤x≤1 and 0≤y≤1.

10. Strained semiconductor heterostructure (10) according to claim 5 or 6, characterized in that the at least one of the following conditions:
said first emitter layer (11) includes Alx1InN1Ga1-x1-Y1Asa1Nb1P1-a1-b1where 0≤x1≤1; 0≤U1≤1; 0≤x1+Y1≤1; 0≤A1≤1; 0<b1≤0,1; 0≤A1+b1≤1;
the specified second emitter layer (12) includes Alx2InU2Ga1-x2-U2As2 Nb2P1-a2-b2where 0≤x2≤1; 0≤U2≤1; 0≤x2+Y2≤1; 0≤A2≤1; 0<b2≤0,1; 0≤A2+b2≤1;
the specified layer (13) generating light includes AlX3InU3Ga1-X3-U3Asa3Nb3P1-a3-b3where 0≤X3≤1; 0≤U3≤1; 0≤X3+U3≤1; 0≤A3≤1; 0<b3≤0,1; 0≤A3+b3≤1;
specified restrictive layer (15) comprises Alx4InA4Ga1-x4-A4Asa4Nb4P1-a4-b4where 0≤x4≤1; 0≤A4≤1; 0≤x4+A4≤1; 0≤A4≤1; 0<b4≤0,1; 0≤A4+b4≤1; and
the specified layer (16) capture includes Alx5InuGa1-x5-uAsa5Nb5P1-a5-b5where 0≤X5≤1; 0≤u≤1; 0≤X5+u≤1; 0≤A5≤1; 0<b5≤0,1; 0≤A5+b5≤1; and these pairs of wide-gap and narrow-gap layers include alternating wide bandgap layers of AlmiInniGa1-mi-niAspiNqiP1-pi-qiand the narrow gap layers of AlkiInliGa1-ki-liAsriNsiP1-ri-siwhere i enumerates pairs, 0≤mi≤1,
0≤ni≤1, 0≤mi+ni≤1, 0≤pi≤1, 0≤qi≤0.1 and 0≤pi+qi≤1, 0≤ki≤1, 0≤li≤1, 0≤ki+li≤1 0≤ri≤1, 0≤si≤0.1 and 0≤ri+si≤1.

11. Light-emitting diode containing the strained semiconductor heterostructure according to any one of claims 1 to 10.

12. Light-emitting diode containing the strained semiconductor heterostructure according to claim 4 or 10, characterized in that
specified strained semiconductor heterostructure grown on a substrate whose material is selected from the group including GaP, GaAs, InP; and
the materials of these first and second e is Echternach layers (11, 12) was selected to ensure coordination of the crystal lattice with the specified substrate.



 

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FIELD: physics.

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Illumination device // 2425432

FIELD: physics.

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FIELD: physics.

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FIELD: physics.

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FIELD: physics.

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16 cl, 8 dwg

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3 cl, 1 dwg, 1 tbl

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12 cl, 12 ex, 6 dwg

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3 cl, 3 tbl, 6 dwg

FIELD: semiconductor emitting devices.

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EFFECT: enlarged ultraviolet emission range of semiconductor element.

1 cl, 1 dwg, 1 tbl

FIELD: semiconductor emitting devices.

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1 cl, 1 dwg, 1 tbl

FIELD: semiconductor optoelectronics; various emitters built around light-emitting diodes.

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EFFECT: ability of shaping desired light-beam emission directivity pattern.

1 cl, 3 dwg

FIELD: semiconductor optoelectronics; various emitters built around light-emitting diodes.

SUBSTANCE: proposed light-emitting diode has light-emitting chip covered by optical component made of translucent material whose outer surface is aspherical in shape due to rotation of curve f(x) built considering optical properties of light-emitting chip and optical component material about symmetry axis of light-emitting diode. This surface emits light and f(x) curve in coordinate system whose origin coincides with geometric center of active area of light-emitting diode has initial point A0 disposed on ordinate axis at distance corresponding to characteristic size of light-emitting diode which is, essentially, optical component height or its desired diameter, and is formed by plurality of points A, (i = 1, 2... n); coordinates of intersection point of straight line drawn from coordinate origin point at angle αini to ordinate axis drawn from preceding point Ai - 1 at angle Gi to abscissa axis drawn to point Ai - 1 are taken as coordinates of each of them;; αini is angle of propagation of iin light beam pertaining to plurality of beams emitted by light-emitting chip chosen between 0 and 90 deg. Angle Gi is found from given dependence. Angle αouti is found by pre-construction of directivity pattern DPin of beam emitted by light-emitting chip. Coordinates of A points are checked by means of light-emitting diode simulator that has optical component whose outline is formed by plurality of Ai points as well as light-emitting chip whose beam directivity pattern is DPin; this chip is used as distributed light source having three-dimensional emitting area whose size and appearance correspond to those of emitting area used in light-emitting diode of light-emitting chip. Light emitting points in light-emitting chip of simulator under discussion are offset relative to origin of coordinates within its emitting area; coordinates of Ai points are checked by comparing directivity pattern DPout and directivity pattern DPsim of beam emitted by light-emitting diode simulator, both displayed in same coordinate system. When these directivity patterns coincide, coordinates of points Ai function as coordinates of points forming curve f(x); if otherwise, coordinates of points Ai are found again, and DPoutj is given as directivity pattern DPout whose points are disposed above or below the latter, respectively, depending on disposition of directivity pattern DPsim below or above directivity pattern DPout in the course of check.

EFFECT: ability of proposed light-emitting diode to shape desired directivity pattern of light beam.

1 cl, 3 dwg

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