Superlattice multispectral infrared detector

Abstract

The invention relates to the technical field of semiconductors, in particular to a superlattice multispectral infrared detector which comprises a substrate and a device structure, the device structure is arranged on the substrate and comprises a buffer layer, a first ohmic contact layer, a long wave absorption layer, an electron barrier layer, a medium wave absorption layer and a second ohmic contact layer, and the buffer layer is arranged on the substrate; the first ohmic contact layer is formed between the buffer layer and the long-wave absorption layer, the electron barrier layer is arranged on the surface, away from the first ohmic contact layer, of the long-wave absorption layer, and the medium-wave absorption layer is arranged between the electron barrier layer and the second ohmic contact layer. In this way, the technical problems that in the prior art, due to the extremely-low-temperature refrigeration technology, the preparation cost of the detector is increased, and the size is increased are solved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a superlattice multi-spectral infrared detector. Background Art

[0002] Infrared detectors are widely used in military and civilian applications. Multi-band infrared detection can simultaneously collect spectral information of target objects in different infrared bands for contrast comparison, which can image the target objects more clearly and accurately. However, in order to improve the imaging quality, the current high-performance dual-channel infrared detectors need to use advanced cooling technology to keep the chip in an extremely low temperature environment to effectively suppress various dark current noises.

[0003] However, in the prior art, the extremely low temperature refrigeration technology used will lead to an increase in the production cost and volume of the detector. Summary of the invention

[0004] The purpose of the present invention is to provide a superlattice multi-spectral infrared detector, aiming to solve the technical problem that the ultra-low temperature refrigeration technology used in the prior art will lead to increased detector preparation costs and increased volume.

[0005] To achieve the above-mentioned purpose, the present invention adopts a superlattice multi-spectral infrared detector, including a substrate and a device structure, wherein the device structure is arranged on the substrate, the device structure includes a buffer layer, a first ohmic contact layer, a long-wave absorption layer, an electron barrier layer, a medium-wave absorption layer and a second ohmic contact layer, and the buffer layer is arranged on the substrate; the first ohmic contact layer is formed between the buffer layer and the long-wave absorption layer, the electron barrier layer is arranged on a side of the long-wave absorption layer away from the first ohmic contact layer, and the medium-wave absorption layer is arranged between the electron barrier layer and the second ohmic contact layer.

[0006] The material of the buffer layer is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 .

[0007] The material of the first ohmic contact layer is any one of N-type heavily doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAsSb, InAs / AlSb / InAsSb superlattice materials, the Sb component is 50%, and the doping concentration is 5×10 18 cm -3 .

[0008] The material of the long-wave absorption layer is any one of undoped or lightly n-type doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAs / InAsSb, InAs / AlSb / InAs / InAsSb superlattice materials, the Sb component is 50%, and the doping concentration is 2×10 15 cm -3 .

[0009] The material of the electron barrier layer is any one of undoped or n-type lightly doped superlattice, AlGaAsSb, AlAsSb / GaSb superlattice, AlGaSb, InAsSb / AlAsSb superlattice, and the doping concentration is 3×10 16 cm -3 .

[0010] The medium wave absorption layer 25 is formed on the electron barrier layer, and the material is undoped or n-type lightly doped InAs / InAsSb superlattice, the Sb component is 50%, and the doping concentration is 1×10 15 cm -3 .

[0011] The material of the second ohmic contact layer is one or more of N-type heavily doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAs / InAsSb, InAs / AlSb / InAs / InAsSb superlattice materials, the Sb component is 50%, and the doping concentration is 5×10 18 cm -3 .

[0012] Wherein, the superlattice multi-spectral infrared detector further comprises a cover layer, and the cover layer is arranged on a side of the second ohmic contact layer away from the medium-wave absorption layer.

[0013] The material of the cap layer is N-type heavily doped InAs with a doping concentration of 5×10 18 cm -3 .

[0014] The cover layer is used to protect the device structure from being damaged.

[0015] A superlattice multi-spectral infrared detector of the present invention uses a new type of Ga-free antimonide superlattice material, which has an extremely high minority carrier lifetime and can greatly suppress the dark current noise dominated by the recombination and diffusion mechanism when the detector is working at high temperature, and eliminate the depletion layer in the absorption region through a unipolar barrier structure, so as to achieve the main dark current noise suppression for the dual-band detector when the working temperature is greater than 150K, improve the working temperature of the dual-band infrared detector, and reduce the device production cost. By voltage modulating the switching process of the dual absorption region channel, a single indium column multi-spectral focal plane planar process can be realized, and the complexity of the detector process is reduced. In this way, the technical problem that the extremely low temperature refrigeration technology used in the prior art will lead to an increase in the preparation cost and volume of the detector is solved.

[0016] The medium-wave and long-wave infrared channels of the present invention use any one of InAs / InSb / InAs / InAsSb, InAs / AlAs / InAsSb, and InAs / AlSb / InAsSb superlattice materials, with a medium-wave cut-off wavelength of 3.9 μm and a long-wave cut-off wavelength of 8.1 μm, which are lattice-matched with the substrate. The Ga-free superlattice structure has an extremely high minority carrier lifetime, can greatly reduce the dark current noise dominated by the recombination and diffusion mechanism, and improve the signal-to-noise ratio of the device at T>150K; the AlAs, AlSb or InSb layer inserted in the InAs layer can enhance the electron-hole wave function overlap of the superlattice, thereby improving the light response of the device.

[0017] The present invention uses any one of AlAs / AlSb / GaSb superlattice, AlGaAsSb, AlAsSb / GaSb superlattice, AlGaSb, and InAsSb / AlAsSb superlattice as the barrier structure, and the band gap width is more than 3 times that of the absorption layer, which can block the surface leakage channel in the absorption region and reduce the depletion layer width, greatly suppress the dark current noise caused by the generation of recombination and surface channels, and is conducive to improving the operating temperature of the device. 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 Schematic diagram of the cross-sectional structure of the superlattice multi-spectral infrared detector of the present invention

[0020] Figure 2The invention relates to the change of the energy band edge position of the InAs / InSb / InAs / InAsSb superlattice at different InAsSb layer thicknesses in the superlattice multi-spectral infrared detector of the present invention.

[0021] Figure 3 It is an energy band diagram of the superlattice multi-spectral infrared detector of the present invention under medium-band operation.

[0022] Figure 4 It is an energy band diagram of the superlattice multi-spectral infrared detector of the present invention when operating in the long-wave band.

[0023] 1-substrate, 2-device structure, 3-cap layer, 21-buffer layer, 22-first ohmic contact layer, 23-long wave absorption layer, 24-electron barrier layer, 25-medium wave absorption layer, 26-second ohmic contact layer. DETAILED DESCRIPTION

[0024] 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.

[0025] See also Figure 1 to Figure 4 ,in Figure 1 A schematic cross-sectional structure diagram of the superlattice multi-spectral infrared detector of the present invention. Figure 2 The invention relates to the change of the energy band edge position of the InAs / InSb / InAs / InAsSb superlattice at different InAsSb layer thicknesses in the superlattice multi-spectral infrared detector of the present invention. Figure 3 It is an energy band diagram of the superlattice multi-spectral infrared detector of the present invention under medium-band operation. Figure 4 It is an energy band diagram of the superlattice multi-spectral infrared detector of the present invention when operating in the long-wave band.

[0026] The present invention provides a superlattice multi-spectral infrared detector, comprising a substrate 1 and a device structure 2, wherein the device structure 2 is arranged on the substrate 1, and the device structure 2 comprises a buffer layer 21, a first ohmic contact layer 22, a long-wave absorption layer 23, an electron barrier layer 24, a medium-wave absorption layer 25, and a second ohmic contact layer 26, wherein the buffer layer 21 is arranged on the substrate 1; the first ohmic contact layer 22 is formed between the buffer layer 21 and the long-wave absorption layer 23, the electron barrier layer 24 is arranged on a side of the long-wave absorption layer 23 away from the first ohmic contact layer 22, and the medium-wave absorption layer 25 is arranged between the electron barrier layer 24 and the second ohmic contact layer 26;

[0027] The material of the buffer layer 21 is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 .

[0028] The material of the first ohmic contact layer 22 is any one of N-type heavily doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAsSb, InAs / AlSb / InAsSb superlattice materials, with Sb content of 50% and doping concentration of 5×10 18 cm -3 ;

[0029] The material of the long-wave absorption layer 23 is any one of undoped or lightly n-type doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAs / InAsSb, InAs / AlSb / InAs / InAsSb superlattice materials, with Sb accounting for 50% and doping concentration of 2×10 15 cm -3 ;

[0030] The material of the electron barrier layer 24 is any one of undoped or n-type lightly doped superlattice, AlGaAsSb, AlAsSb / GaSb superlattice, AlGaSb, InAsSb / AlAsSb superlattice, with a doping concentration of 3×10 16 cm -3 ;

[0031] The medium wave absorption layer 2525 is formed on the electron barrier layer 24, and the material is undoped or n-type lightly doped InAs / InAsSb superlattice, the Sb component is 50%, and the doping concentration is 1×10 15 cm -3 ;

[0032] The material of the second ohmic contact layer 26 is one or more of N-type heavily doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAs / InAsSb, InAs / AlSb / InAs / InAsSb superlattice materials, with Sb content of 50% and doping concentration of 5×10 18 cm -3 ;

[0033] With respect to this specific embodiment, the present invention uses a new type of Ga-free antimonide superlattice material, which has an extremely high minority carrier lifetime, and can greatly suppress the dark current noise dominated by the recombination and diffusion mechanism when the detector is working at high temperature, and eliminate the depletion layer in the absorption region through the unipolar barrier structure, thereby achieving the main dark current noise suppression for the dual-band detector when the operating temperature is greater than 150K, improving the operating temperature of the dual-band infrared detector, and reducing the device production cost. By voltage modulating the switching process of the dual absorption zone channel, a single indium column multi-spectral focal plane planar process can be realized, reducing the complexity of the detector process, and in this way solving the technical problem that the ultra-low temperature refrigeration technology used in the prior art will lead to increased detector preparation cost and increased volume.

[0034] The medium-wave and long-wave infrared channels of the present invention use any one of InAs / InSb / InAs / InAsSb, InAs / AlAs / InAsSb, and InAs / AlSb / InAsSb superlattice materials, with a medium-wave cut-off wavelength of 3.9 μm and a long-wave cut-off wavelength of 8.1 μm, which are lattice-matched with the substrate 1. The Ga-free superlattice structure has an extremely high minority carrier lifetime, which can greatly reduce the dark current noise dominated by the recombination and diffusion mechanism, and improve the signal-to-noise ratio of the device at T>150K; the AlAs, AlSb or InSb layer inserted in the InAs layer can enhance the electron-hole wave function overlap of the superlattice, thereby improving the light response of the device.

[0035] The present invention uses any one of AlAs / AlSb / GaSb superlattice, AlGaAsSb, AlAsSb / GaSb superlattice, AlGaSb, and InAsSb / AlAsSb superlattice as the barrier structure, and the band gap width is more than 3 times that of the absorption layer, which can block the surface leakage channel in the absorption region and reduce the depletion layer width, greatly suppress the dark current noise caused by the generation of recombination and surface channels, and is conducive to improving the operating temperature of the device.

[0036] Wherein, the superlattice multi-spectral infrared detector further includes a cover layer 3, and the cover layer 3 is arranged on a side of the second ohmic contact layer 26 away from the medium-wave absorption layer 25;

[0037] The material of the cap layer 3 is N-type heavily doped InAs with a doping concentration of 5×10 18 cm -3 .

[0038] According to this specific embodiment, the cover layer 3 is used to protect the device structure 2 from being damaged.

[0039] A superlattice multi-spectral infrared detector using the present embodiment uses a new type of Ga-free antimonide superlattice material, which has an extremely high minority carrier lifetime and can greatly suppress the dark current noise dominated by the recombination and diffusion mechanism when the detector is working at high temperature, and eliminate the depletion layer in the absorption region through the unipolar barrier structure, thereby achieving the main dark current noise suppression for the dual-band detector when the operating temperature is greater than 150K, increasing the operating temperature of the dual-band infrared detector, and reducing the device production cost. By voltage modulating the switching process of the dual absorption region channel, a single indium column multi-spectral focal plane planar process can be realized, reducing the complexity of the detector process, thereby solving the technical problem that the extremely low temperature refrigeration technology used in the prior art will lead to increased detector preparation cost and increased volume.

[0040] The medium-wave and long-wave infrared channels of the present invention use any one of InAs / InSb / InAs / InAsSb, InAs / AlAs / InAsSb, and InAs / AlSb / InAsSb superlattice materials, with a medium-wave cut-off wavelength of 3.9 μm and a long-wave cut-off wavelength of 8.1 μm, which are lattice-matched with the substrate 1. The Ga-free superlattice structure has an extremely high minority carrier lifetime, which can greatly reduce the dark current noise dominated by the recombination and diffusion mechanism, and improve the signal-to-noise ratio of the device at T>150K; the AlAs, AlSb or InSb layer inserted in the InAs layer can enhance the electron-hole wave function overlap of the superlattice, thereby improving the light response of the device.

[0041] The present invention uses any one of AlAs / AlSb / GaSb superlattice, AlGaAsSb, AlAsSb / GaSb superlattice, AlGaSb, and InAsSb / AlAsSb superlattice as the barrier structure, and the band gap width is more than 3 times that of the absorption layer, which can block the surface leakage channel in the absorption region and reduce the depletion layer width, greatly suppress the dark current noise caused by the generation of recombination and surface channels, and is conducive to improving the operating temperature of the device.

[0042] See also Figure 1 The material of the substrate 1 is N-type heavily doped GaSb, and the crystal plane is (001). The material of the buffer layer 21 is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 , which can prevent the propagation of defects at the substrate 1, including dislocations and point defects, and make the surface smoother;

[0043] Depend on Figure 2It can be seen that when the Sb component in the InAsSb ternary alloy is maintained at 50%, in order to maintain the strain balance between the superlattice and the GaSb substrate 1, the thickness of the InAs layer should also be increased accordingly when the thickness of the InAsSb material is increased. In this process, the conduction band position of the superlattice is maintained near -0.15 eV, and the valence band will increase rapidly with the increase in the thickness of the InAsSb layer, thereby reducing the effective band gap width of the superlattice and realizing the transition of the cutoff wavelength of the absorption layer from the medium wave to the long wave direction. Optionally, the composition of the medium wave absorption layer 25 is 6InAs / AlSb / 6InAs / 2InAs 0.5 Sb 0.5 , the cut-off wavelength is 3.9 μm, and the composition of the long-wave absorption layer 23 is 12InAs / InSb / 12InAs / / 4InAs 0.5 Sb 0.5 , the cut-off wavelength is 8.1 μm, and the valence band height difference between the two channels is 0.06 eV. In order to maintain the lattice matching between the electron barrier layer 24 and the substrate 1, the layer thickness needs to satisfy AlAs / (AlSb+AlAs)=8%, and the band gap width and valence band position of the barrier can be adjusted by the thickness of the GaSb layer. In the embodiment of the present invention, the band gap of the electron barrier layer 24 is optionally greater than 1 eV, which is more than 3 times the band gap width of the dual channel absorption region;

[0044] based on Figure 3 , Figure 3 The upper middle curve (Ec) is the electron minimum energy curve, and the lower curve (Ev) is the hole minimum energy curve. At this time, the bias voltage of the device is 0V, so the medium wave channel can operate at quantum efficiency saturation at 0 bias. Since the dual-channel absorption region is intrinsically biased to n, the minority carriers are holes, so the light response is mainly generated by the transport of photogenerated holes in the valence band, and the built-in electric field of the electron barrier layer 24 is the key to the transport of photogenerated holes. In this embodiment, since the band gap width of the electron barrier layer 24 is more than 3 times that of the dual absorption region, the depletion layer falls into the electron barrier layer 24, which completely suppresses the generation of composite dark current noise. At the same time, since the surface leakage channel of InAs / InSb / InAs / InAsSb is higher than the conduction band of the absorption layer, the surface leakage current will also be suppressed by the electron barrier layer 24. The valence band of the medium-wave channel is lower than the electron barrier layer 24, so the photogenerated holes in the medium-wave channel under zero bias are affected by the built-in electric field and are not hindered by the heterojunction interface when transported to the first ohmic contact layer 22, and the saturated working mode of the medium-wave absorption layer 25 can be achieved under zero bias. However, the valence band position of the long-wave absorption layer 23 is higher than the corresponding valence band of the electron barrier layer 24, so at the heterojunction of the long-wave channel and the electron barrier under zero bias, the photogenerated holes will be hindered by the built-in electric field in the electron barrier layer 24, and the long-wave channel cannot be opened;

[0045] based on Figure 4 , Figure 4 The upper middle curve (Ec) is the electron minimum energy curve, and the lower curve (Ev) is the hole minimum energy curve. At this time, the external bias voltage of the second ohmic contact layer 26 is 0.3V, which causes the valence band position of the long-wave absorption layer 23 to be lower than the corresponding valence band of the electron barrier layer 24, and realizes the reversal of the direction of the built-in electric field in the electron barrier layer 24. At this time, the photogenerated carriers in the long-wave channel will be accelerated by the built-in electric field in the electron barrier layer 24 and transported to the first ohmic contact layer 22, while the medium-wave channel is affected by a large heterojunction barrier between the medium-wave channel and the electron barrier layer 24, and the photogenerated holes in the medium-wave channel will be blocked by the built-in electric field of the electron barrier layer 24, and the medium-wave channel cannot be transported.

[0046] 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 superlattice multi-spectral infrared detector, characterized in that: It comprises a substrate and a device structure, wherein the device structure is arranged on the substrate, the device structure comprises a buffer layer, a first ohmic contact layer, a long-wave absorption layer, an electron barrier layer, a medium-wave absorption layer and a second ohmic contact layer, and the buffer layer is arranged on the substrate; the first ohmic contact layer is formed between the buffer layer and the long-wave absorption layer, the electron barrier layer is arranged on a side of the long-wave absorption layer away from the first ohmic contact layer, and the medium-wave absorption layer is arranged between the electron barrier layer and the second ohmic contact layer.

2. The superlattice multi-spectral infrared detector according to claim 1, characterized in that: The material of the buffer layer is GaSb doped with Te or InAs doped with Si. 0.91 Sb 0.09 .

3. The superlattice multi-spectral infrared detector according to claim 2, characterized in that: The material of the first ohmic contact layer is any one of N-type heavily doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAsSb, InAs / AlSb / InAsSb superlattice materials, the Sb component is 50%, and the doping concentration is 5×10 18 cm -3 .

4. The superlattice multi-spectral infrared detector according to claim 3, characterized in that: The material of the long-wave absorption layer is any one of undoped or lightly n-type doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAs / InAsSb, InAs / AlSb / InAs / InAsSb superlattice materials, the Sb component is 50%, and the doping concentration is 2×10 15 cm -3 .

5. The superlattice multi-spectral infrared detector according to claim 4, characterized in that: The material of the electron barrier layer is any one of undoped or n-type lightly doped superlattice, AlGaAsSb, AlAsSb / GaSb superlattice, AlGaSb, InAsSb / AlAsSb superlattice, and the doping concentration is 3×10 16 cm -3 .

6. The superlattice multi-spectral infrared detector according to claim 5, characterized in that: The medium wave absorption layer 25 is formed on the electron barrier layer, and the material is undoped or n-type lightly doped InAs / InAsSb superlattice, the Sb component is 50%, and the doping concentration is 1×10 15 cm -3 .

7. The superlattice multi-spectral infrared detector according to claim 6, characterized in that: The material of the second ohmic contact layer is one or more of N-type heavily doped InAs / InSb / InAs / InAsSb, InAs / AlAs / InAs / InAsSb, InAs / AlSb / InAs / InAsSb superlattice materials, the Sb component is 50%, and the doping concentration is 5×10 18 cm -3 .

8. The superlattice multi-spectral infrared detector according to claim 7, characterized in that: The superlattice multi-spectral infrared detector further comprises a cover layer, and the cover layer is arranged on a side of the second ohmic contact layer away from the medium-wave absorption layer.

9. The superlattice multi-spectral infrared detector according to claim 8, characterized in that: The material of the cap layer is N-type heavily doped InAs with a doping concentration of 5×10 18 cm -3 .

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