High-temperature superlattice infrared detector
By setting an interface gradient doping layer between the medium wave absorption layer and the electron barrier layer of the infrared detector, the problem of large detector volume and high manufacturing cost under low temperature refrigeration technology is solved, and the effect of high-efficiency imaging and low refrigeration cost is achieved at high temperatures.
Patent Information
- Application Number
- CN202510130932.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-06
- Publication Date
- 2025-05-09
AI Technical Summary
In the prior art, when low-temperature refrigeration technology is adopted, the lower the refrigeration temperature, the more complex the structure of the refrigerator, resulting in a larger detector volume and higher manufacturing cost.
Using a high-temperature superlattice infrared detector, by setting an interface gradient doping layer between the medium-wave absorption layer and the electron barrier layer, the width of the depletion region and the electric field intensity near the interface of the medium-wave absorption layer are reduced, the composite dark current noise is suppressed, and the quantum efficiency and working temperature are improved.
It realizes that while maintaining high quantum efficiency at high temperatures, the refrigeration cost and volume of the detector are reduced, and the working temperature of the detector can be improved for high performance imaging.
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Figure CN119967945A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a high-temperature superlattice infrared detector. Background Art
[0002] Infrared detectors are widely used in resource exploration, astronomical observation, medical imaging and other fields. At present, for mid-infrared band (3μm-5μm) detection, in order to improve the working performance of the detector, low-temperature refrigeration technology is needed to reduce the packaging temperature of the detector chip.
[0003] When using low-temperature refrigeration technology, the lower the refrigeration temperature, the more complex the refrigerator structure, which in turn leads to a larger detector size and higher manufacturing cost. Summary of the invention
[0004] The purpose of the present invention is to provide a high-temperature superlattice infrared detector, aiming to solve the technical problem in the prior art that when using low-temperature refrigeration technology, the lower the refrigeration temperature, the more complex the refrigerator structure, which leads to a larger detector size and higher manufacturing cost.
[0005] To achieve the above-mentioned purpose, the present invention adopts a high-temperature superlattice infrared detector, including a substrate, a device component and a cover layer, wherein the device component is arranged between the substrate and the cover layer, and the device component includes a buffer layer, a first ohmic contact layer, a medium-wave absorption layer, an interface gradient doping layer, an electron barrier region and a second ohmic contact layer, the buffer layer is arranged on a side of the substrate close to the cover layer, the first ohmic contact layer is arranged between the buffer layer and the medium-wave absorption layer, the interface gradient doping layer is arranged on a side of the medium-wave absorption layer away from the first ohmic contact layer, the electron barrier region is arranged between the interface gradient doping layer and the second ohmic contact layer, and the second ohmic contact layer is connected to the cover layer.
[0006] The substrate is made of GaSb and doped with Te at a concentration of 10 18 cm -3 , thickness is 600μm.
[0007] The material of the buffer layer is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 material, with a doping concentration of 2×10 18 cm -3 , thickness is 1μm.
[0008] Among them, the material of the first ohmic contact layer is N-type heavily doped InAs 1-x1 Sb x1 With InAs 1-x2 Sbx2 The superlattice formed has a doping concentration of 2×10 18 cm -3 , thickness is 300-500nm.
[0009] The material of the medium wave absorption layer is undoped or lightly n-doped InAs. 1-x1 Sb x1 With InAs 1-x2 Sb x2 The formed superlattice has a doping concentration of less than 5×10 15 cm -3 , the cut-off wavelength reaches 5μm at 150K.
[0010] The material of the interface gradient doping layer is undoped or lightly n-type doped InAs. 1-x1 Sb x1 With InAs 1- x2 Sb x2 The superlattice formed has a thickness of 100-200nm, and the doping concentration increases from 5×10 15 cm -3 Gradient to 1×10 17 cm -3 .
[0011] The material of the electron barrier layer is one of non-intentionally doped AlAs / AlSb, AlAsSb / InAsSb superlattice or AlGaAsSb quaternary alloy, and the thickness is 80-200nm.
[0012] The material of the second ohmic contact layer is InAs / InAsSb superlattice doped with Be element, with a thickness of 100-500nm and a p-type doping concentration of 2×10 18 cm -3 .
[0013] The material of the cap layer is InAs doped with Be, with a thickness of 10 nm and a p-type doping concentration of 2×10 18 cm -3 .
[0014] A high-temperature superlattice infrared detector of the present invention achieves double gradient of the composition and doping of the interface of the interface gradient doping layer arranged between the medium-wave absorption layer and the electron barrier layer, so that the absorption region of the infrared detector can reduce the depletion region width and electric field strength near the interface of the medium-wave absorption layer while maintaining the high quantum efficiency characteristics of non-doping, suppress or eliminate the generation of composite dark current noise in the depletion layer of the device in the absorption region, improve the quantum efficiency of the device, increase the operating temperature of the detector for high-performance imaging, and reduce the refrigeration cost. In this way, the technical problem in the prior art that when using low-temperature refrigeration technology, the lower the refrigeration temperature, the more complex the structure of the refrigerator, which leads to a larger detector size and higher manufacturing cost is solved.
[0015] The present invention uses InAs 1-x1 Sb x1 / InAs 1-x2 Sb x2 The formed superlattice serves as a mid-wave infrared receiving zone with a cutoff wavelength of 5μm at 150K, which can cover the entire mid-wave infrared detection band.
[0016] The present invention can reduce the turn-on bias and saturation bias of the device by intentionally doping p in the electrode region, which is beneficial to improving the response uniformity when preparing the focal plane device.
[0017] The present invention can effectively suppress the expansion of the depletion layer in the absorption region while ensuring the efficient transport of photogenerated carriers, suppress the generation of recombination effects during high-temperature operation, greatly improve the effective operating temperature of the device, and reduce the volume of the refrigeration unit and production cost of the device through intentional gradual doping of the heterojunction interface layer between the medium-wave absorption layer and the electron barrier region and double gradual change of the superlattice components at the interface boundary of the absorption region. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0019] Figure 1 It is a band structure diagram of a device in the prior art.
[0020] Figure 2 It is the electric field distribution diagram of the device in the prior art.
[0021] Figure 3 2 is an energy band structure diagram of the device of the present invention.
[0022] Figure 4 It is the electric field distribution diagram of the device of the present invention.
[0023] Figure 5 It is a schematic diagram of the cross-sectional structure of the high-temperature superlattice infrared detector of the present invention.
[0024] 1-substrate, 2-device component, 3-cap layer, 4-buffer layer, 5-first ohmic contact layer, 6-medium wave absorption layer, 7-interface gradient doping layer, 8-electron barrier region, 9-second ohmic contact layer. DETAILED DESCRIPTION
[0025] Embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.
[0026] See also Figure 1 to Figure 5 ,in Figure 1 It is a band structure diagram of a device in the prior art. Figure 2 It is the electric field distribution diagram of the device in the prior art. Figure 3 2 is an energy band structure diagram of the device of the present invention. Figure 4 It is the electric field distribution diagram of the device of the present invention. Figure 5 It is a schematic diagram of the cross-sectional structure of the high-temperature superlattice infrared detector of the present invention.
[0027] The present invention provides a high-temperature superlattice infrared detector, comprising a substrate 1, a device component 2 and a cover layer 3, wherein the device component 2 is arranged between the substrate 1 and the cover layer 3, and the device component 2 comprises a buffer layer 21, a first ohmic contact layer 22, a medium-wave absorption layer 23, an interface gradient doping layer 24, an electron barrier region 25 and a second ohmic contact layer 26, wherein the buffer layer 21 is arranged on a side of the substrate 1 close to the cover layer 3, the first ohmic contact layer 22 is arranged between the buffer layer 21 and the medium-wave absorption layer 23, the interface gradient doping layer 24 is arranged on a side of the medium-wave absorption layer 23 away from the first ohmic contact layer 22, the electron barrier region 25 is arranged between the interface gradient doping layer 24 and the second ohmic contact layer 26, and the second ohmic contact layer 26 is connected to the cover layer 3;
[0028] The substrate 1 is made of GaSb material and doped with Te element at a doping concentration of 10 18 cm -3 , thickness is 600μm;
[0029] The material of the buffer layer 21 is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 material, with a doping concentration of 2×10 18 cm -3 , thickness is 1 μm;
[0030] The material of the first ohmic contact layer 22 is N-type heavily doped InAs. 1-x1 Sb x1 With InAs 1-x2 Sb x2 The superlattice formed has a doping concentration of 2×10 18 cm -3 , thickness is 300-500nm;
[0031] The material of the medium wave absorption layer 23 is undoped or lightly n-doped InAs. 1-x1 Sb x1 With InAs 1-x2 Sb x2 The formed superlattice has a doping concentration of less than 5×10 15 cm -3 , the cut-off wavelength is 5μm at 150K;
[0032] The material of the interface gradient doping layer 24 is undoped or lightly n-doped InAs. 1-x1 Sb x1 With InAs 1-x2 Sb x2 The superlattice formed has a thickness of 100-200nm, and the doping concentration increases from 5×10 15 cm -3 Gradient to 1×10 17 cm -3 ; By gradually increasing the x2 component and gradually decreasing the x1 component, the increase in the x2 component can raise the valence band at the interface and promote the transport of photogenerated holes, while the decrease in the x1 component can reduce the conduction band height at the interface and eliminate the local hole barrier caused by gradual doping. Optionally, x2 increases from 34% to 50%, and x1 decreases from 4% to 2%.
[0033] The material of the electron barrier layer is one of non-intentionally doped AlAs / AlSb, AlAsSb / InAsSb superlattice or AlGaAsSb quaternary alloy, and the thickness is 80-200nm;
[0034] The material of the second ohmic contact layer 26 is InAs / InAsSb superlattice doped with Be element, with a thickness of 100-500nm and a p-type doping concentration of 2×10 18 cm -3 .
[0035] The material of the cap layer 3 is InAs doped with Be, with a thickness of 10 nm and a p-type doping concentration of 2×10 18 cm -3 .
[0036] With respect to this specific embodiment, by providing a double gradient of the composition and doping of the interface of the interface gradient doping layer 24 arranged between the medium-wave absorption layer 23 and the electron barrier layer, the infrared detector absorption region can reduce the depletion region width and the electric field strength near the interface of the medium-wave absorption layer 23 while maintaining the high quantum efficiency characteristics of non-doping, thereby suppressing or eliminating the generation of composite dark current noise in the depletion layer of the device in the absorption region, improving the quantum efficiency of the device, increasing the operating temperature of the detector for high-performance imaging, and reducing the refrigeration cost. In this way, the technical problem in the prior art that when using low-temperature refrigeration technology, the lower the refrigeration temperature, the more complex the structure of the refrigerator, which leads to a larger detector size and higher manufacturing cost is solved.
[0037] See also Figure 1 , Figure 1 The energy band structure diagram of the device is shown when the heterojunction interface near the junction of the medium-wave absorption layer 23 and the electron barrier region 25 is uniformly doped. 1-x1 Sb x1 / InAs 1-x2 Sb x2 The superlattice is usually not intentionally doped and has an intrinsic bias of n, while the electron barrier region 25 uses the AlAs / AlSb superlattice with an intrinsic bias of p, which will produce a very wide depletion layer near the heterojunction at x=2.7um, causing the absorption layer near the interface to be completely depleted, with a high composite dark current generated, resulting in the degradation of the high-temperature operating characteristics of the device.
[0038] See also Figure 2 , Figure 2 The energy band structure diagram of the device when uniformly doped near the heterojunction interface at the junction of the medium wave absorption layer 23 and the electron barrier region 25 is shown. Along the growth direction, there is a strong electric field in the medium wave absorption layer 23 with a thickness of 2.1μm-2.7μm, indicating that the device is in a strong depletion state within the width of the medium wave absorption layer 23. A stronger electric field will lead to a higher recombination rate.
[0039] See also Figure 3 , Figure 3The energy band structure diagram of the double gradient structure device near the heterojunction interface at the junction of the medium-wave absorption layer 23 and the electron barrier region 25 is shown. At this time, under the design of non-doping, only a very narrow absorption region near the heterojunction interface at 2.7 μm is in a depletion state, and the degree of band bending in the depletion state is much lower than that of the device with uniform interface doping. Therefore, the theoretical recombination rate near the interface of the heterojunction is extremely low, which is conducive to eliminating the generation of recombination dark current of the device, so that the dark current mechanism of the device when working in the high temperature section is transferred from the dominant generation of recombination to the dominant diffusion mechanism, thereby greatly reducing the dark current noise of the device at the same operating temperature. At the same time, the non-doped absorption region has a higher quantum efficiency. The bandgap width of the electron barrier region 25 is greater than 1eV, which is more than twice that of the infrared detection absorption layer and is in a completely depleted state.
[0040] See also Figure 4 , Figure 4 The electric field distribution diagram of the double gradient structure device near the heterojunction interface at the junction of the medium-wave absorption layer 23 and the electron barrier region 25 is shown. A significant electric field strength will only be generated in the infrared detection absorption layer at a device thickness of 2.5μm-2.7μm, and the depletion width in the medium-wave absorption layer 23 is less than 0.2μm. Compared with 1 / 3 of the absorption layer depletion width in the interface uniformly doped structure, the narrower depletion layer width can suppress the generation of composite dark current in the absorption layer, thereby greatly reducing the dark current noise at the same temperature, and achieving an increase in the high-performance operating temperature of the device. Since the bandgap width of the electron barrier region 25 is more than twice that of the medium-wave absorption layer 23, the electron barrier region 25 is in a fully depleted state, where the peak electric field strength is at the heterojunction interface position, exceeding 3×10 4 V / cm, which can maintain efficient transport of photogenerated holes. By intentionally doping the second ohmic contact layer 26 with p, the electron accumulation phenomenon at the heterojunction of the second ohmic contact layer 26 and the electron barrier region 25 can be eliminated, the influence of hole transport to the interface potential energy of the second ohmic contact layer 26 and the electron barrier region 25 can be reduced, the saturation working bias of the device can be reduced, and zero bias saturation of the device is expected to be achieved.
[0041] The present invention uses InAs 1-x1 Sb x1 / InAs 1-x2 Sb x2 The formed superlattice serves as a mid-wave infrared receiving zone with a cutoff wavelength of 5μm at 150K, which can cover the entire mid-wave infrared detection band.
[0042] The present invention can reduce the turn-on bias and saturation bias of the device by intentionally doping p in the electrode region, which is beneficial to improving the response uniformity when preparing the focal plane device.
[0043] The present invention can effectively suppress the expansion of the depletion layer in the absorption region while ensuring the efficient transport of photogenerated carriers, suppress the generation of recombination effects during high-temperature operation, greatly improve the effective operating temperature of the device, and reduce the volume of the refrigeration unit and production cost of the device by intentionally gradient doping the heterojunction interface layer between the medium-wave absorption layer 23 and the electron barrier region 25 and double gradient of the superlattice components at the interface boundary of the absorption region.
[0044] A high-temperature superlattice infrared detector using the present embodiment is configured to achieve double gradients in the composition and doping of the interface of the interface gradient doping layer 24 arranged between the medium-wave absorption layer 23 and the electron barrier layer, so that the absorption region of the infrared detector can maintain the high quantum efficiency characteristics of non-doping while reducing the depletion region width and electric field strength near the interface of the medium-wave absorption layer 23, thereby suppressing or eliminating the generation of composite dark current noise in the depletion layer of the device in the absorption region and improving the quantum efficiency of the device, thereby increasing the operating temperature of the detector for high-performance imaging and reducing the refrigeration cost. In this way, the technical problem in the prior art that when using low-temperature refrigeration technology, the lower the refrigeration temperature, the more complex the structure of the refrigerator, which leads to a larger detector size and higher manufacturing cost is solved.
[0045] The present invention uses InAs 1-x1 Sb x1 / InAs 1-x2 Sb x2 The formed superlattice serves as a mid-wave infrared receiving zone with a cutoff wavelength of 5μm at 150K, which can cover the entire mid-wave infrared detection band.
[0046] The present invention can reduce the turn-on bias and saturation bias of the device by intentionally doping p in the electrode region, which is beneficial to improving the response uniformity when preparing the focal plane device.
[0047] The present invention can effectively suppress the expansion of the depletion layer in the absorption region while ensuring the efficient transport of photogenerated carriers, suppress the generation of recombination effects during high-temperature operation, greatly improve the effective operating temperature of the device, and reduce the volume of the refrigeration unit and production cost of the device by intentionally gradient doping the heterojunction interface layer between the medium-wave absorption layer 23 and the electron barrier region 25 and double gradient of the superlattice components at the interface boundary of the absorption region.
[0048] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.
Claims
1. A high-temperature superlattice infrared detector, characterized in that: The invention comprises a substrate, a device component and a cover layer, wherein the device component is arranged between the substrate and the cover layer, and the device component comprises a buffer layer, a first ohmic contact layer, a medium-wave absorption layer, an interface gradient doping layer, an electron barrier region and a second ohmic contact layer, wherein the buffer layer is arranged on a side of the substrate close to the cover layer, the first ohmic contact layer is arranged between the buffer layer and the medium-wave absorption layer, the interface gradient doping layer is arranged on a side of the medium-wave absorption layer away from the first ohmic contact layer, the electron barrier region is arranged between the interface gradient doping layer and the second ohmic contact layer, and the second ohmic contact layer is connected to the cover layer.
2. The high temperature superlattice infrared detector according to claim 1, characterized in that: The substrate is made of GaSb material and doped with Te element at a doping concentration of 10 18 cm -3 , thickness is 600μm.
3. The high temperature superlattice infrared detector according to claim 2, characterized in that: The material of the buffer layer is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 material, with a doping concentration of 2×10 18 cm -3 , thickness is 1μm.
4. The high temperature superlattice infrared detector according to claim 3, characterized in that: The material of the first ohmic contact layer is N-type heavily doped InAs 1-x1 Sb x1 With InAs 1-x2 Sb x2 The superlattice formed has a doping concentration of 2×10 18 cm -3 , thickness is 300-500nm.
5. The high temperature superlattice infrared detector according to claim 4, characterized in that: The material of the medium wave absorption layer is undoped or lightly n-doped InAs. 1-x1 Sb x1 With InAs 1-x2 Sb x2 The formed superlattice has a doping concentration of less than 5×10 15 cm -3 , the cut-off wavelength reaches 5μm at 150K.
6. The high temperature superlattice infrared detector according to claim 5, characterized in that: The material of the interface gradient doping layer is undoped or n-type lightly doped InAs 1-x1 Sb x1 With InAs 1-x2 Sb x2 The superlattice formed has a thickness of 100-200nm, and the doping concentration increases from 5×10 15 cm -3 Gradient to 1×10 17 cm -3 .
7. The high temperature superlattice infrared detector according to claim 6, characterized in that: The material of the electron barrier layer is one of non-intentionally doped AlAs / AlSb, AlAsSb / InAsSb superlattice or AlGaAsSb quaternary alloy, and the thickness is 80-200nm.
8. The high temperature superlattice infrared detector according to claim 7, characterized in that: The material of the second ohmic contact layer is InAs / InAsSb superlattice doped with Be element, with a thickness of 100-500nm and a p-type doping concentration of 2×10 18 cm -3 .
9. The high temperature superlattice infrared detector according to claim 8, characterized in that: The material of the cap layer is InAs doped with Be element, with a thickness of 10 nm and a p-type doping concentration of 2×10 18 cm -3 .