Inter-band cascade detector and manufacturing method thereof

Abstract

The present invention provides an inter-band cascade detector and a manufacturing method thereof. The inter-band cascade detector is composed of multiple cascade steps, each of which includes an electron barrier layer, a superlattice absorption region and a hole barrier layer. The first to third superlattice absorption regions use InAs / InAsSb type II superlattices, which not only maintain the inherent advantages of the inter-band cascade detector, but also reduce the dark current level, thereby improving the detection rate of the inter-band cascade detector.

Description

Technical Field

[0001] The present invention relates to the technical field of detector design, and more particularly to an inter-band cascade detector and a manufacturing method thereof. Background Art

[0002] With the continuous development of science and technology, infrared detectors have been widely used in military and civilian fields such as infrared guidance, night vision, atmospheric detection and medicine due to their excellent performance.

[0003] For MCT and InAsSb detectors, most are based on PIN or single-stage barrier (e.g. nBn) structures. High-temperature performance is limited by high dark current levels, reduced diffusion lengths, and the inability to collect photogenerated carriers.

[0004] For detectors with PIN or single-stage barrier (such as nBn) structures, the inventors found that increasing the thickness of the absorption region will increase its quantum efficiency, but the dark current level will also increase. When the absorption region exceeds the critical thickness, the detector's detection rate will decrease. The theoretically achievable maximum detector decreases as the diffusion length shortens, especially at high temperatures, when the carrier mobility and lifetime decrease, causing the diffusion length to shorten rapidly.

[0005] Based on the inter-band cascade detector, it is a special multi-level infrared detector structure, each level is composed of an electron barrier, an absorption region and a hole barrier. Its rectification characteristics rely on this complementary barrier, rather than the traditional PN junction. Since there is no depletion layer, the tunneling current and the generated recombination current can be greatly reduced. Furthermore, the complementary barrier structure can also achieve the effect of self-passivation, especially for the second type of superlattice detector, the surface leakage current is one of the main factors limiting the performance of the detector. This special multi-level structure can also reduce noise and increase the operating temperature, similar to the quantum well infrared detector (QWIP) in which the noise is reduced to 1 / N (N is the number of quantum wells). In addition, due to the thin thickness of the absorption region, the photogenerated carriers can be almost completely collected, especially at high temperatures, the diffusion length of the carriers becomes rapidly shortened.

[0006] It can be seen that the inter-band cascade detector has obvious advantages over the traditional PIN or single-stage barrier (such as nBn) structure detectors in high temperature environment.

[0007] However, current interband cascade detectors have problems such as short carrier lifetime and low detection rate. Summary of the invention

[0008] In view of this, in order to solve the above problems, the present invention provides an inter-band cascade detector and a manufacturing method thereof, and the technical solution is as follows:

[0009] An inter-band cascade detector, the inter-band cascade detector comprising:

[0010] substrate;

[0011] On one side of the substrate, a third electron barrier layer, a third InAs / InAsSb superlattice absorption region, a third hole barrier layer, a second electron barrier layer, a second InAs / InAsSb superlattice absorption region, a second hole barrier layer, a first electron barrier layer, a first InAs / InAsSb superlattice absorption region and a first hole barrier layer are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the third electron barrier layer;

[0012] The thickness of the first-level InAs / InAsSb superlattice absorption region is smaller than the thickness of the second-level InAs / InAsSb superlattice absorption region, and the thickness of the third-level InAs / InAsSb superlattice absorption region.

[0013] Optionally, in the above-mentioned inter-band cascade detector, the substrate is a GaSb substrate.

[0014] Optionally, in the above-mentioned inter-band cascade detector, the growth period of the third-stage InAs / InAsSb superlattice absorption region is 130-160;

[0015] In each of the growth cycles, the thickness of the InAs layer is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm;

[0016] The third-level InAs / InAsSb superlattice absorption region is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0017] Optionally, in the above-mentioned inter-band cascade detector, the growth period of the second-stage InAs / InAsSb superlattice absorption region is 100-130;

[0018] In each of the growth cycles, the thickness of the InAs layer is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm;

[0019] The second-level InAs / InAsSb superlattice absorption region is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0020] Optionally, in the above-mentioned inter-band cascade detector, the growth period of the first-stage InAs / InAsSb superlattice absorption region is 70-100;

[0021] In each of the growth cycles, the thickness of the InAs layer is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm;

[0022] The first-level InAs / InAsSb superlattice absorption region is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0023] Optionally, in the above-mentioned inter-band cascade detector, the substrate is an InAs substrate.

[0024] Optionally, in the above-mentioned inter-band cascade detector, the growth period of the third-level InAs / InAsSb superlattice absorption region is 110-130;

[0025] In each of the growth cycles, the thickness of the InAs layer is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm;

[0026] The third-level InAs / InAsSb superlattice absorption region is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0027] Optionally, in the above-mentioned inter-band cascade detector, the growth period of the second-stage InAs / InAsSb superlattice absorption region is 80-110;

[0028] In each of the growth cycles, the thickness of the InAs layer is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm;

[0029] The second-level InAs / InAsSb superlattice absorption region is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0030] Optionally, in the above-mentioned inter-band cascade detector, the growth period of the first-stage InAs / InAsSb superlattice absorption region is 50-80;

[0031] In each of the growth cycles, the thickness of the InAs layer is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm;

[0032] The first-level InAs / InAsSb superlattice absorption region is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0033] A method for manufacturing an inter-band cascade detector, the manufacturing method comprising:

[0034] providing a substrate;

[0035] On one side of the substrate, a third electron barrier layer, a third InAs / InAsSb superlattice absorption region, a third hole barrier layer, a second electron barrier layer, a second InAs / InAsSb superlattice absorption region, a second hole barrier layer, a first electron barrier layer, a first InAs / InAsSb superlattice absorption region and a first hole barrier layer are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the third electron barrier layer;

[0036] The thickness of the first-level InAs / InAsSb superlattice absorption region is smaller than the thickness of the second-level InAs / InAsSb superlattice absorption region, and the thickness of the third-level InAs / InAsSb superlattice absorption region.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides an inter-band cascade detector comprising: a substrate; on one side of the substrate, a third-level electron barrier layer, a third-level InAs / InAsSb superlattice absorption region, a third-level hole barrier layer, a second-level electron barrier layer, a second-level InAs / InAsSb superlattice absorption region, a second-level hole barrier layer, a first-level electron barrier layer, a first-level InAs / InAsSb superlattice absorption region and a first-level hole barrier layer are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the third-level electron barrier layer; wherein the thickness of the first-level InAs / InAsSb superlattice absorption region is less than the thickness of the second-level InAs / InAsSb superlattice absorption region and the thickness of the third-level InAs / InAsSb superlattice absorption region, matching between various levels of photocurrent is achieved; and the first to third superlattice absorption regions adopt InAs / InAsSb type II superlattice, which not only maintains the inherent advantages of the inter-band cascade detector, but also reduces the dark current level, thereby improving the detection rate of the inter-band cascade detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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 embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0040] Figure 1 A schematic diagram of the structure of an inter-band cascade detector provided by an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the structure of another inter-band cascade detector provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the structure of another inter-band cascade detector provided by an embodiment of the present invention;

[0043] Figure 4 A schematic flow chart of a method for manufacturing an inter-band cascade detector provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] During the invention process of the present invention, the inventors discovered that the interband cascade detector whose absorption region is composed of InAs / GaSb type II superlattice has a lower Auger recombination rate and a longer carrier lifetime in theory, and has a larger effective electron mass and a lower tunneling current than the mercury cadmium telluride material.

[0046] Although the Auger recombination rate is theoretically predicted to be low, the experimentally measured carrier lifetimes of InAs / GaSb type II superlattices are generally not high. For example, through time-domain or frequency-domain photoluminescence experiments, the measured carrier lifetimes in the medium-wave and long-wave ranges are 30ns-100ns, 10ns, and 55ns, respectively.

[0047] The inventors found that the shorter carrier lifetime is due to the introduction of Ga-related defect levels in the bandgap, which become Shockley-Read-Hall (abbreviated as SRH) recombination centers, resulting in the carrier lifetime being determined by SRH recombination.

[0048] Based on the above technical problems, the inventors also found that, unlike the InAs / GaSb type II superlattice, the InAs / InAsSb type II superlattice does not contain the Ga element and internal radiative recombination is dominant, so the carrier lifetime will become much longer. For example, the experimentally measured value is longer than 400ns. In view of the longer carrier lifetime, the dark current level of the InAs / InAsSb type II superlattice detector is lower.

[0049] Therefore, the present invention provides an inter-band cascade detector based on the InAs / InAsSb type II superlattice, which not only maintains the inherent advantages of the inter-band cascade detector, but also reduces the dark current level, thereby improving the detection rate of the inter-band cascade detector.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] refer to Figure 1 , Figure 1 A schematic diagram of the structure of an inter-band cascade detector provided in an embodiment of the present invention.

[0052] The inter-band cascade detector comprises:

[0053] Substrate 11;

[0054] On one side of the substrate 11, a third-level electron barrier layer 12, a third-level InAs / InAsSb superlattice absorption region 13, a third-level hole barrier layer 14, a second-level electron barrier layer 15, a second-level InAs / InAsSb superlattice absorption region 16, a second-level hole barrier layer 17, a first-level electron barrier layer 18, a first-level InAs / InAsSb superlattice absorption region 19 and a first-level hole barrier layer 20 are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate 11 and points from the substrate 11 to the third-level electron barrier layer 12;

[0055] The thickness of the first-level InAs / InAsSb superlattice absorption region 19 is smaller than the thickness of the second-level InAs / InAsSb superlattice absorption region 16 , which is smaller than the thickness of the third-level InAs / InAsSb superlattice absorption region 13 .

[0056] In this embodiment, the thickness of each level of absorption region decreases successively in the first direction in order to achieve photocurrent matching between each level.

[0057] In addition, the first to third superlattice absorption regions use InAs / InAsSb type II superlattice, which not only maintains the inherent advantages of the interband cascade detector, but also reduces the dark current level, thereby improving the detection rate of the interband cascade detector.

[0058] It should be noted that when the substrate of the inter-band cascade detector is selected differently, the specific structure of the inter-band cascade detector provided by the embodiment of the present invention is also different, which will be explained one by one below.

[0059] Further, based on the above embodiments of the present invention, refer to Figure 2 , Figure 2 A schematic diagram of the structure of another inter-band cascade detector provided in an embodiment of the present invention.

[0060] The substrate 11 is a GaSb substrate 111 .

[0061] Optionally, the substrate 11 is a p-type GaSb substrate 111 .

[0062] like Figure 2 As shown, the inter-band cascade detector comprises:

[0063] The GaSb buffer layer 21 is disposed on the GaSb substrate 111; the GaSb buffer layer 21 is p-type doped, and the doping concentration is 1×10 17 cm -3 -1×10 18 cm -3 .

[0064] An AlSb / GaSb multi-quantum well transition layer 22 is arranged on the side of the GaSb buffer layer 21 away from the GaSb substrate 111; the AlSb / GaSb multi-quantum well transition layer 22 is composed of 2 to 4 groups of AlSb / GaSb quantum wells, wherein the thickness of the AlSb layer is 1nm-2nm, and the thickness of the GaSb layer is 8nm-10nm. It should be noted that neither the AlSb layer nor the GaSb layer has any doping.

[0065] The third-level electron barrier layer 12 is arranged on the side of the AlSb / GaSb multi-quantum well transition layer 22 away from the GaSb substrate 111; the third-level electron barrier layer 12 is composed of 3-4 groups of AlSb / GaSb quantum wells, wherein the thickness of the AlSb layer is 1nm-2nm and there is no doping; the thickness of the GaSb layer is 2nm-8nm, it is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

[0066] The third-level InAs / InAsSb superlattice absorption region 13 is arranged on the side of the third-level electron barrier layer 12 away from the GaSb substrate 111; the growth period of the third-level InAs / InAsSb superlattice absorption region 13 is 130-160; that is, the third-level InAs / InAsSb superlattice absorption region 13 is composed of a 130-160 period strain-balanced InAs / InAsSb superlattice; the thickness of the InAs layer in each growth period is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm; the third-level InAs / InAsSb superlattice absorption region 13 is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

[0067] The third-level hole barrier layer 14 is arranged on the side of the third-level InAs / InAsSb superlattice absorption region 13 away from the GaSb substrate 111; the third-level hole barrier layer 14 is composed of 7-8 groups of AlSb / InAs quantum wells, wherein the thickness of the AlSb layer is 1nm-2nm without any doping; the thickness of the InAs layer is 2nm-8nm, which is partially n-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 It should be noted that the thickness of the InAs layer gradually increases, which causes the electron energy level in the quantum well to gradually decrease, thus achieving electron relaxation.

[0068] The second electron barrier layer 15 is arranged on the side of the third hole barrier layer 14 away from the GaSb substrate 111 . It should be noted that the thickness and doping of each layer of the second electron barrier layer 15 and the third electron barrier layer 12 are exactly the same.

[0069] The second-level InAs / InAsSb superlattice absorption region 16 is arranged on the side of the second-level electron barrier layer 15 away from the GaSb substrate 111; the growth period of the second-level InAs / InAsSb superlattice absorption region 16 is 100-130; that is, the second-level InAs / InAsSb superlattice absorption region 16 is composed of a 100-130 period strain-balanced InAs / InAsSb superlattice; the thickness of the InAs layer in each growth period is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm; the second-level InAs / InAsSb superlattice absorption region 16 is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17cm -3 .

[0070] A second hole barrier layer 17 is arranged on the side of the second InAs / InAsSb superlattice absorption region 16 away from the GaSb substrate 111 ; it should be noted that the thickness and doping of each layer of the second hole barrier layer 17 and the third hole barrier layer 14 are exactly the same.

[0071] The first-level electron barrier layer 18 is arranged on the side of the second-level hole barrier layer 17 away from the GaSb substrate 111 ; it should be noted that the thickness and doping of each layer of the first-level electron barrier layer 18 and the third-level electron barrier layer 12 are exactly the same.

[0072] The first-level InAs / InAsSb superlattice absorption region 19 is arranged on the side of the first-level electron barrier layer 19 away from the GaSb substrate 111; the growth period of the first-level InAs / InAsSb superlattice absorption region 19 is 70-100; that is, the first-level InAs / InAsSb superlattice absorption region 19 is composed of a 70-100 period strain-balanced InAs / InAsSb superlattice; the thickness of the InAs layer in each growth period is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm; the first-level InAs / InAsSb superlattice absorption region 19 is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

[0073] A first-level hole barrier layer 20 is arranged on the side of the first-level InAs / InAsSb superlattice absorption region 19 away from the GaSb substrate 111 ; it should be noted that the thickness and doping of each layer of the first-level hole barrier layer 20 and the third-level hole barrier layer 14 are exactly the same.

[0074] The InAs contact layer 23 is disposed on the side of the first-stage hole barrier layer 20 away from the GaSb substrate 111. The InAs contact layer 23 has a thickness of 20 nm to 30 nm and is n-type doped with a doping concentration of 1×10 18 cm -3 -1×10 19 cm -3 .

[0075] Optionally, the inter-band cascade detector includes:

[0076] An upper electrode 26 is disposed on a side of the InAs contact layer 23 away from the GaSb substrate 111 .

[0077] The lower electrode 27 is disposed on the side of the GaSb buffer layer 21 away from the GaSb substrate 111 .

[0078] Optionally, the upper electrode 26 and the lower electrode 27 have the same structure and material, and are both multi-layer metal structures, such as a multi-layer metal structure of 20nmTi / 50nmPt / 300nmAu.

[0079] Furthermore, in a specific embodiment of the present invention, an inter-band cascade detector is provided, and the 78K response cutoff wavelength is 5.3 μm, wherein:

[0080] The GaSb buffer layer 21 has a thickness of 500 nm and is p-type doped with a doping concentration of 2.0×10 17 cm -3 .

[0081] The AlSb / GaSb multi-quantum well transition layer 22 consists of two groups of AlSb / GaSb quantum wells. In the first group of quantum wells, the thickness of the AlSb layer is 1.5nm, and the thickness of the GaSb layer is 10nm; in the second group of quantum wells, the thickness of the AlSb layer is 1.5nm, and the thickness of the GaSb layer is 8.3nm.

[0082] The third-level electron barrier layer 12 is composed of 4 groups of AlSb / GaSb quantum wells. In the first group of quantum wells, the thickness of the AlSb layer is 1.2 nm, and the thickness of the GaSb layer is 7.3 nm; in the second group of quantum wells, the thickness of the AlSb layer is 1.3 nm, and the thickness of the GaSb layer is 5.6 nm; in the third group of quantum wells, the thickness of the AlSb layer is 1.3 nm, and the thickness of the GaSb layer is 4.0 nm; in the fourth group of quantum wells, the thickness of the AlSb layer is 1.4 nm, and the thickness of the GaSb layer is 2.4 nm; it should be noted that the AlSb layer in all quantum wells is not doped, and the GaSb layer is p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0083] The growth period of the third-level InAs / InAsSb superlattice absorption region 13 is 148, and the thickness of the InAs layer in each growth period is 1.4 nm. 0.65 Sb 0.35 The thickness of the layer is 4.1 nm, and all layers are p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0084] The third-level hole barrier layer 14 is composed of 7 groups of AlSb / InAs quantum wells. In the first group of quantum wells, the thickness of the AlSb layer is 1.7 nm, and the thickness of the InAs layer is 4.8 nm; in the second group of quantum wells, the thickness of the AlSb layer is 1.6 nm, and the thickness of the InAs layer is 5.0 nm; in the third group of quantum wells, the thickness of the AlSb layer is 1.6 nm, and the thickness of the InAs layer is 5.2 nm; in the fourth group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 5.5 nm; in the fifth group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 5.8 nm; in the sixth group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 6.2 nm; in the seventh group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 7.0 nm; it should be noted that the AlSb layer in all quantum wells is not doped, and some InAs layers are n-type doped with a doping concentration of 1.5×10 17 cm -3 .

[0085] The thickness and doping of each layer of the second electron barrier layer 15 and the third electron barrier layer 12 are completely the same.

[0086] The growth period of the second-level InAs / InAsSb superlattice absorption region 16 is 113, and the thickness of the InAs layer in each growth period is 1.4 nm. 0.65 Sb 0.35 The thickness of the layer is 4.1 nm, and all layers are p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0087] The thickness and doping of each layer of the second hole barrier layer 17 and the third hole barrier layer 14 are completely the same.

[0088] The thickness and doping of each layer of the first-level electron barrier layer 18 and the third-level electron barrier layer 12 are completely the same.

[0089] The growth period of the first-level InAs / InAsSb superlattice absorption region 19 is 92, and the thickness of the InAs layer in each growth period is 1.4 nm. 0.65 Sb 0.35 The thickness of the layer is 4.1 nm, and all layers are p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0090] The thickness and doping of each layer of the first-level hole barrier layer 20 and the third-level hole barrier layer 14 are completely the same.

[0091] The thickness of the InAs contact layer 23 is 25 nm, and it is n-type doped with a doping concentration of 1.0×10 18 cm -3 .

[0092] Further, based on the above embodiments of the present invention, refer to Figure 3 , Figure 3 A schematic diagram of the structure of another inter-band cascade detector provided in an embodiment of the present invention.

[0093] The substrate 11 is an InAs substrate.

[0094] Optionally, the substrate 11 is an n-type InAs substrate 112 .

[0095] like Figure 3 As shown, the inter-band cascade detector comprises:

[0096] An InAs buffer layer 24 is provided on the InAs substrate 112; the InAs buffer layer 24 is n-type doped, and the doping concentration is 1×10 17 cm -3 -1×10 18 cm -3 .

[0097] The third electron barrier layer 12 is arranged on the side of the InAs buffer layer 24 away from the InAs substrate 112; the third electron barrier layer 12 is composed of 3-4 groups of AlSb / GaSb quantum wells, wherein the thickness of the AlSb layer is 1nm-2nm without any doping; the thickness of the GaSb layer is 2nm-8nm, which is p-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 .

[0098] The third-level InAs / InAsSb superlattice absorption region 13 is arranged on the side of the third-level electron barrier layer 12 away from the InAs substrate 112; the growth period of the third-level InAs / InAsSb superlattice absorption region 13 is 110-130; that is, the third-level InAs / InAsSb superlattice absorption region 13 is composed of a 110-130 period strained InAs / InAsSb superlattice; the thickness of the InAs layer in each growth period is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm; the third-level InAs / InAsSb superlattice absorption region 13 is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

[0099] The third-level hole barrier layer 14 is arranged on the side of the third-level InAs / InAsSb superlattice absorption region 13 away from the InAs substrate 112; the third-level hole barrier layer 14 is composed of 7-8 groups of AlSb / InAs quantum wells, wherein the thickness of the AlSb layer is 1nm-2nm without any doping; the thickness of the InAs layer is 2nm-8nm, which is partially n-type doped with a doping concentration of 1×10 16 cm -3 -1×10 17 cm -3 It should be noted that the thickness of the InAs layer gradually increases, which causes the electron energy level in the quantum well to gradually decrease, thus achieving electron relaxation.

[0100] The second electron barrier layer 15 is arranged on the side of the third hole barrier layer 14 away from the InAs substrate 112 . It should be noted that the thickness and doping of each layer of the second electron barrier layer 15 and the third electron barrier layer 12 are exactly the same.

[0101] The second-level InAs / InAsSb superlattice absorption region 16 is arranged on the side of the second-level electron barrier layer 15 away from the InAs substrate 112; the growth period of the second-level InAs / InAsSb superlattice absorption region 16 is 80-110; that is, the second-level InAs / InAsSb superlattice absorption region 16 is composed of 80-110 period strained InAs / InAsSb superlattice; the thickness of the InAs layer in each growth period is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm; the second-level InAs / InAsSb superlattice absorption region 16 is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

[0102] A second-level hole barrier layer 17 is disposed on the side of the second-level InAs / InAsSb superlattice absorption region 16 away from the InAs substrate 112 . It should be noted that the thickness and doping of each layer of the second-level hole barrier layer 17 and the third-level hole barrier layer 14 are exactly the same.

[0103] The first-level electron barrier layer 18 is arranged on the side of the second-level hole barrier layer 17 away from the InAs substrate 112 ; it should be noted that the thickness and doping of each layer of the first-level electron barrier layer 18 and the third-level electron barrier layer 12 are exactly the same.

[0104] The first-level InAs / InAsSb superlattice absorption region 19 is arranged on the side of the first-level electron barrier layer 18 away from the InAs substrate 112; the growth period of the first-level InAs / InAsSb superlattice absorption region 19 is 50-80; that is, the first-level InAs / InAsSb superlattice absorption region 19 is composed of a 50-80 period strained InAs / InAsSb superlattice; the thickness of the InAs layer in each growth period is 1nm-5nm, and the thickness of the InAsSb layer is 1nm-5nm; the first-level InAs / InAsSb superlattice absorption region 19 is p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

[0105] A first-level hole barrier layer 20 is disposed on the side of the first-level InAs / InAsSb superlattice absorption region 19 away from the InAs substrate 112 ; it should be noted that the thickness and doping of each layer of the first-level hole barrier layer 20 and the third-level hole barrier layer 14 are exactly the same.

[0106] The GaSb contact layer 25 is disposed on the side of the first-stage hole barrier layer 20 away from the InAs substrate 112. The GaSb contact layer 25 has a thickness of 20 nm to 30 nm and is p-type doped with a doping concentration of 1×10 18 cm -3 -1×10 19 cm -3 .

[0107] Optionally, the inter-band cascade detector includes:

[0108] An upper electrode 26 is disposed on the side of the GaSb contact layer 25 facing away from the InAs substrate 112 .

[0109] The lower electrode 27 is disposed on a side of the InAs buffer layer 24 away from the InAs substrate 112 .

[0110] Optionally, the upper electrode 26 and the lower electrode 27 have the same structure and material, and are both multi-layer metal structures, such as a multi-layer metal structure of 20nmTi / 50nmPt / 300nmAu.

[0111] Furthermore, in a specific embodiment of the present invention, an inter-band cascade detector is provided, and the 78K response cutoff wavelength is 5.5 μm, wherein:

[0112] The thickness of the InAs buffer layer 24 is 500 nm, and the n-type doping concentration is 1.0×10 17 cm-3 .

[0113] The third-level electron barrier layer 12 is composed of 4 groups of AlSb / GaSb quantum wells. In the first group of quantum wells, the thickness of the AlSb layer is 1.2 nm, and the thickness of the GaSb layer is 7.3 nm; in the second group of quantum wells, the thickness of the AlSb layer is 1.3 nm, and the thickness of the GaSb layer is 5.6 nm; in the third group of quantum wells, the thickness of the AlSb layer is 1.4 nm, and the thickness of the GaSb layer is 4.0 nm; in the fourth group of quantum wells, the thickness of the AlSb layer is 1.3 nm, and the thickness of the GaSb layer is 2.4 nm; it should be noted that the AlSb layer in all quantum wells is not doped, and the GaSb layer is p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0114] The growth period of the third-level InAs / InAsSb superlattice absorption region 13 is 121, and the thickness of the InAs layer in each growth period is 4.8nm. 0.91 Sb 0.09 The thickness of the layer is 1.9 nm, and all layers are p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0115] The third-level hole barrier layer 14 is composed of 7 groups of AlSb / InAs quantum wells. In the first group of quantum wells, the thickness of the AlSb layer is 1.7 nm, and the thickness of the InAs layer is 4.7 nm; in the second group of quantum wells, the thickness of the AlSb layer is 1.6 nm, and the thickness of the InAs layer is 5.0 nm; in the third group of quantum wells, the thickness of the AlSb layer is 1.6 nm, and the thickness of the InAs layer is 5.2 nm; in the fourth group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 5.5 nm; in the fifth group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 5.8 nm; in the sixth group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 6.2 nm; in the seventh group of quantum wells, the thickness of the AlSb layer is 1.5 nm, and the thickness of the InAs layer is 7.1 nm; it should be noted that the AlSb layer in all quantum wells is not doped, and some InAs layers are n-type doped with a doping concentration of 1.5×10 17 cm -3 .

[0116] The thickness and doping of each layer of the second electron barrier layer 15 and the third electron barrier layer 12 are completely the same.

[0117] The growth period of the second-level InAs / InAsSb superlattice absorption region 16 is 93, and the thickness of the InAs layer in each growth period is 4.8 nm. 0.91 Sb 0.09 The thickness of the layer is 1.9 nm, and all layers are p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0118] The thickness and doping of each layer of the second hole barrier layer 17 and the third hole barrier layer 14 are completely the same.

[0119] The thickness and doping of each layer of the first-level electron barrier layer 18 and the third-level electron barrier layer 12 are completely the same.

[0120] The growth period of the first-level InAs / InAsSb superlattice absorption region 19 is 75, and the thickness of the InAs layer in each growth period is 4.8 nm. 0.91 Sb 0.09 The thickness of the layer is 1.9 nm, and all layers are p-type doped with a doping concentration of 2.4×10 16 cm -3 .

[0121] The thickness and doping of each layer of the first-level hole barrier layer 20 and the third-level hole barrier layer 14 are completely the same.

[0122] The GaSb contact layer 25 has a thickness of 25 nm and is p-type doped with a doping concentration of 1.0×10 18 cm -3 .

[0123] From the above description, it can be seen that the present invention provides an inter-band cascade detector based on the InAs / InAsSb type II superlattice, which not only maintains the inherent advantages of the inter-band cascade detector, but also reduces the dark current level, thereby improving the detection rate of the inter-band cascade detector.

[0124] Based on all the above embodiments of the present invention, another embodiment of the present invention further provides a method for manufacturing an inter-band cascade detector, referring to Figure 4 , Figure 4 A schematic flow chart of a method for manufacturing an inter-band cascade detector provided in an embodiment of the present invention.

[0125] The production method comprises:

[0126] S101: providing a substrate.

[0127] S102: On one side of the substrate, a third electron barrier layer, a third InAs / InAsSb superlattice absorption region, a third hole barrier layer, a second electron barrier layer, a second InAs / InAsSb superlattice absorption region, a second hole barrier layer, a first electron barrier layer, a first InAs / InAsSb superlattice absorption region and a first hole barrier layer are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the third electron barrier layer; wherein the thickness of the first InAs / InAsSb superlattice absorption region is less than the thickness of the second InAs / InAsSb superlattice absorption region and the thickness of the third InAs / InAsSb superlattice absorption region.

[0128] The above is a detailed introduction to an inter-band cascade detector and a method for manufacturing the same provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0129] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0130] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0131] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An inter-band cascade detector, characterized in that: The inter-band cascade detector comprises: The substrate is a GaSb substrate or an InAs substrate; On one side of the substrate, a third-level electron barrier layer, a third-level InAs / InAsSb superlattice absorption region, a third-level hole barrier layer, a second-level electron barrier layer, a second-level InAs / InAsSb superlattice absorption region, a second-level hole barrier layer, a first-level electron barrier layer, a first-level InAs / InAsSb superlattice absorption region and a first-level hole barrier layer are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the third-level electron barrier layer; wherein the thickness of the first-level InAs / InAsSb superlattice absorption region is less than the thickness of the second-level InAs / InAsSb superlattice absorption region, and the thickness of the third-level InAs / InAsSb superlattice absorption region is less than the thickness of the third-level InAs / InAsSb superlattice absorption region; If the substrate is a GaSb substrate, the growth period of the third-level InAs / InAsSb superlattice absorption region is 130-160, the growth period of the second-level InAs / InAsSb superlattice absorption region is 100-130, and the growth period of the first-level InAs / InAsSb superlattice absorption region is 70-100; wherein, in each growth period, the thickness of the InAs layer is 1nm-5nm, the thickness of the InAsSb layer is 1nm-5nm, and the third-level InAs / InAsSb superlattice absorption region, the second-level InAs / InAsSb superlattice absorption region and the first-level InAs / InAsSb superlattice absorption region are all p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 ; If the substrate is an InAs substrate, the growth period of the third-level InAs / InAsSb superlattice absorption region is 110-130, the growth period of the second-level InAs / InAsSb superlattice absorption region is 80-110, and the growth period of the first-level InAs / InAsSb superlattice absorption region is 50-80; wherein, in each of the growth periods, the thickness of the InAs layer is 1nm-5nm, the thickness of the InAsSb layer is 1nm-5nm, and the third-level InAs / InAsSb superlattice absorption region, the second-level InAs / InAsSb superlattice absorption region and the first-level InAs / InAsSb superlattice absorption region are all p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

2. A method for manufacturing an inter-band cascade detector, characterized in that: The production method comprises: Providing a GaSb substrate or an InAs substrate; On one side of the substrate, a third-level electron barrier layer, a third-level InAs / InAsSb superlattice absorption region, a third-level hole barrier layer, a second-level electron barrier layer, a second-level InAs / InAsSb superlattice absorption region, a second-level hole barrier layer, a first-level electron barrier layer, a first-level InAs / InAsSb superlattice absorption region and a first-level hole barrier layer are sequentially arranged along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the third-level electron barrier layer; wherein the thickness of the first-level InAs / InAsSb superlattice absorption region is less than the thickness of the second-level InAs / InAsSb superlattice absorption region, and the thickness of the third-level InAs / InAsSb superlattice absorption region is less than the thickness of the third-level InAs / InAsSb superlattice absorption region; If the substrate is a GaSb substrate, the growth period of the third-level InAs / InAsSb superlattice absorption region is 130-160, the growth period of the second-level InAs / InAsSb superlattice absorption region is 100-130, and the growth period of the first-level InAs / InAsSb superlattice absorption region is 70-100; wherein, in each growth period, the thickness of the InAs layer is 1nm-5nm, the thickness of the InAsSb layer is 1nm-5nm, and the third-level InAs / InAsSb superlattice absorption region, the second-level InAs / InAsSb superlattice absorption region and the first-level InAs / InAsSb superlattice absorption region are all p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 ; If the substrate is an InAs substrate, the growth period of the third-level InAs / InAsSb superlattice absorption region is 110-130, the growth period of the second-level InAs / InAsSb superlattice absorption region is 80-110, and the growth period of the first-level InAs / InAsSb superlattice absorption region is 50-80; wherein, in each of the growth periods, the thickness of the InAs layer is 1nm-5nm, the thickness of the InAsSb layer is 1nm-5nm, and the third-level InAs / InAsSb superlattice absorption region, the second-level InAs / InAsSb superlattice absorption region and the first-level InAs / InAsSb superlattice absorption region are all p-type doped, and the doping concentration is 1×10 16 cm -3 -1×10 17 cm -3 .

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