An infrared detector with a graded barrier of nBn type

Abstract

The present invention discloses an infrared detector with a graded barrier of the nBn type, belonging to the technical field of infrared detectors. The purpose is to provide an infrared detector with a graded barrier of the nBn type. Based on the designed structure of the graded barrier, while ensuring that the electron barrier is high enough, the influence of the hole barrier on the hole carrier transport is weakened by means of graded material composition. It includes a substrate, on the upper surface of which a buffer layer, a lower contact layer, an absorption layer, a barrier layer, and an upper contact layer are sequentially arranged from bottom to top. A first electrode is arranged on the upper surface of the lower contact layer, and a second electrode is arranged on the upper surface of the upper contact layer. The absorption layer is InAs 0.91 Sb 0.09 material, and the barrier layer is a graded combination of AlAs 0.08 Sb 0.92 ~AlSb. The graded combination of AlAs 0.08 Sb 0.92 ~AlSb is gradually changed from AlSb to AlAs 0.08 Sb 0.92。 uniformly from bottom to top. The present invention is applicable to an infrared detector with a graded barrier of the nBn type.

Description

Technical Field

[0001] The present invention belongs to the technical field of infrared detectors, and particularly relates to an infrared detector with a graded barrier of nBn type. Background Art

[0002] Mid-wave infrared (MWIR) detectors are widely used in many military and civilian applications, including gas detection, pollutant detection, infrared thermal imaging, etc. Most mid-wave infrared detectors operate normally at low temperatures. Recently, many progresses have been made in increasing the operating temperature to achieve high operating temperature (HOT) detectors. In the prior art of high operating temperature devices, the nBn type barrier infrared detector is considered to be one of the most suitable methods to achieve high operating temperature detectors. It was first proposed by Maimon and Wicks in 2006. The insertion of a wide-bandgap barrier eliminates the formation of a potential depletion region between the barrier layer and the absorption layer. The high conduction band barrier between the absorption layer and the barrier layer blocks the majority carriers (electrons), enabling the detector to operate at a significantly high temperature. The application of the wide-bandgap barrier brings new problems. A relatively high valence band energy difference is formed between the barrier layer and the absorption layer, which hinders the transport of photo-generated carriers, making the device need to operate at a higher voltage and further increasing the load of the readout circuit.

[0003] An ideal nBn detector requires a sufficiently high conduction band barrier and a low valence band barrier. Based on InAs x Sb 1-x -based nBn type infrared detectors have advantages such as a wide spectral range, low electron effective mass, low Auger recombination rate, and high mobility at room temperature, and are important alternatives to HgCdTe ternary alloys and InSb MWIR detectors.

[0004] InAs x Sb 1-x -AlAs 0.08 Sb 0.92 is usually used as the absorption-barrier combination in nBn type infrared detectors. However, the valence band energy difference between the absorption layer and the barrier layer of this material pair is about 170 meV. Such a high energy difference is equivalent to a hole barrier, which hinders the transport of photo-generated carriers and results in a reduction in device performance. Summary of the Invention

[0005] The purpose of the present invention is to provide an infrared detector with a graded barrier of nBn type. Based on the design structure of the graded barrier, while ensuring that the electron barrier is sufficiently high, the influence of the hole barrier on the transport of hole carriers is weakened by means of a graded material composition.

[0006] The technical solution adopted by the present invention is as follows:

[0007] An infrared detector with a graded barrier of the nBn type, comprising a substrate, on the upper surface of which a buffer layer, a lower contact layer, an absorption layer, a barrier layer, and an upper contact layer are sequentially arranged from bottom to top. A first electrode is arranged on the upper surface of the lower contact layer, and a second electrode is arranged on the upper surface of the upper contact layer. The absorption layer is InAs 0.91 Sb 0.09 material, and the barrier layer is a graded combination of AlAs 0.08 Sb 0.92 ~AlSb.

[0008] Further, the graded combination of AlAs 0.08 Sb 0.92 ~AlSb is gradually changed from AlSb to AlAs 0.08 Sb 0.92 uniformly from bottom to top.

[0009] Further, the first electrode is a Ti / Au electrode, and the second electrode is a Ti / Au electrode.

[0010] Further, the lower contact layer is InAs 0.91 Sb 0.09 material, and the upper contact layer is InAs 0.91 Sb 0.09 material.

[0011] Further, the substrate is made of GaSb material.

[0012] Further, the buffer layer is made of GaSb material.

[0013] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0014] 1. In the present invention, InAs 0.91 Sb 0.09 is used as the absorption layer, and the graded combination of AlAs 0.08 Sb 0.92 ~AlSb is used as the barrier layer. By means of the grading method, taking advantage of the fact that the valence band of AlSb is close to that of InAs 0.91 Sb 0.09 , and the property that AlAs 0.08 Sb 0.92 is completely lattice-matched with InAs 0.91 Sb 0.09 , the barrier material is gradually changed from AlSb to AlAs 0.08 Sb 0.92The valence band energy difference between the barrier layer and the absorption layer is slowly increased, weakening the hindrance of the valence band energy difference to photo-generated carriers, thereby improving the hole collection efficiency, reducing the device operating voltage, achieving effective collection of photo-generated carriers by the device at low bias voltages, enhancing the detector efficiency, and being suitable for barrier detectors of more material systems at the same time, improving the design flexibility based on semiconductor heterojunctions.

[0015] 2. In the present invention, compared with using AlAs alone 0.08 Sb 0.92 as the barrier region material, at the same bias voltage, the device using the graded barrier structure achieves higher performance, effectively suppresses the Shockley-Read-Hall process, reduces the generation-recombination dark current, improves the device operation stability, improves the detection performance of the device at the same temperature, or raises the operating temperature of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts, where:

[0017] Figure 1 is a schematic structural diagram of the present invention;

[0018] Figure 2 is a schematic diagram of the energy band structures of the graded barrier and traditional non-graded barrier devices of the present invention;

[0019] Figure 3 is an enlarged schematic diagram of the energy band structure of the barrier layer of the present invention;

[0020] Figure 4 is a comparison diagram of the responsivities of the graded barrier and traditional non-graded barrier devices of the present invention;

[0021] Figure 5 is a comparison diagram of the detectivities of the graded barrier and traditional non-graded barrier devices of the present invention;

[0022] Reference numerals in the figures: 1 - substrate, 2 - buffer layer, 3 - lower contact layer, 4 - absorption layer, 5 - barrier layer, 6 - upper contact layer, 7 - first electrode, 8 - second electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. The components of the embodiments of the present invention usually described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the detailed description of the embodiments of the present invention provided in the drawings below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0025] It should be noted that: reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0026] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and is a simplified description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0027] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0028] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Combined with the attached Figure 1 - attached Figure 5 .

[0030] An infrared detector with a graded barrier of the nBn type, comprising a substrate, on the upper surface of which a buffer layer, a lower contact layer, an absorption layer, a barrier layer, and an upper contact layer are sequentially arranged from bottom to top. A first electrode is arranged on the upper surface of the lower contact layer, and a second electrode is arranged on the upper surface of the upper contact layer. The absorption layer is InAs 0.91 Sb 0.09 material, and the barrier layer is a graded combination of AlAs 0.08 Sb 0.92 ~AlSb.

[0031] Furthermore, the graded combination of AlAs 0.08 Sb 0.92 ~AlSb is gradually changed from AlSb to AlAs uniformly from bottom to top 0.08 Sb 0.92 .

[0032] Furthermore, the first electrode is a Ti / Au electrode, and the second electrode is a Ti / Au electrode.

[0033] Furthermore, the lower contact layer is InAs 0.91 Sb 0.09 material, and the upper contact layer is InAs 0.91 Sb 0.09 material.

[0034] Furthermore, the substrate is made of GaSb material.

[0035] Furthermore, the buffer layer is made of GaSb material.

[0036] In the implementation process of the present invention, InAs 0.91 Sb 0.09 is used as the absorption layer, and the graded combination of AlAs 0.08 Sb 0.92 ~AlSb is used as the barrier layer. Through the graded manner, taking advantage of the property that the valence band of AlSb is close to that of InAs 0.91 Sb 0.09 , and the fact that AlAs 0.08 Sb 0.92 is completely lattice-matched with InAs 0.91 Sb 0.09 , the barrier material is gradually changed from AlSb to AlAs 0.08 Sb 0.92The valence band energy difference between the barrier layer and the absorption layer is slowly increased, weakening the hindrance effect of the valence band energy difference on the photo-generated carriers, thereby improving the hole collection efficiency, reducing the device operating voltage, achieving effective collection of photo-generated carriers by the device at low bias voltages, enhancing the detector efficiency, and at the same time being suitable for barrier detectors of more material systems, improving the design flexibility based on semiconductor heterojunctions.

[0037] At the same time, compared with using AlAs alone 0.08 Sb 0.92 As the barrier region material, at the same bias voltage, the device using the graded barrier structure achieves higher performance, effectively suppresses the Shockley-Read-Hall process, reduces the generation-recombination dark current, improves the device operation stability, improves the detection performance of the device at the same temperature, or increases the operating temperature of the device.

[0038] Example 1

[0039] An nBn-type graded barrier infrared detector includes a substrate, on the upper surface of which a buffer layer, a lower contact layer, an absorption layer, a barrier layer, and an upper contact layer are sequentially arranged from bottom to top. A first electrode is arranged on the upper surface of the lower contact layer, and a second electrode is arranged on the upper surface of the upper contact layer. The absorption layer is made of InAs 0.91 Sb 0.09 material, and the barrier layer is a graded combination of AlAs 0.08 Sb 0.92 ~AlSb.

[0040] Example 2

[0041] Based on Example 1, the graded combination of AlAs 0.08 Sb 0.92 ~AlSb is gradually changed from AlSb to AlAs uniformly from bottom to top 0.08 Sb 0.92 .

[0042] Example 3

[0043] Based on the above embodiments, the first electrode is a Ti / Au electrode, and the second electrode is a Ti / Au electrode.

[0044] Example 4

[0045] Based on the above embodiments, the lower contact layer is made of InAs 0.91 Sb 0.09 material, and the upper contact layer is made of InAs 0.91 Sb 0.09 material.

[0046] Example 5

[0047] Based on the above embodiments, the substrate is made of GaSb material.

[0048] Embodiment 6

[0049] Based on the above embodiments, the buffer layer is made of GaSb material.

[0050] As described above are the embodiments of the present invention. The foregoing are the various preferred embodiments of the present invention. If the preferred implementation manners in each preferred embodiment are not obviously self - contradictory or premised on a certain preferred implementation manner, the various preferred implementation manners can be arbitrarily superimposed and combined for use. The embodiments and the specific parameters in the embodiments are only for clearly expressing the verification process of the invention, and are not used to limit the patent protection scope of the present invention. The patent protection scope of the present invention still takes its claims as the criterion. All equivalent changes made by using the description of the present invention should, by the same token, be included in the protection scope of the present invention.

Claims

1. An infrared detector with a graded potential barrier of the nBn type, characterized in that, It includes a substrate (1), on the upper surface of which a buffer layer (2), a lower contact layer (3), an absorption layer (4), a barrier layer (5), and an upper contact layer (6) are sequentially arranged from bottom to top. A first electrode (7) is provided on the upper surface of the lower contact layer (3), and a second electrode (8) is provided on the upper surface of the upper contact layer (6). The absorption layer is InAs 0.91 Sb 0.09 material, and the barrier layer is a graded combination of AlAs 0.08 Sb 0.92 ~AlSb. The graded combination of AlAs 0.08 Sb 0.92 ~AlSb is gradually and uniformly changed from AlSb to AlAs from bottom to top 0.08 Sb 0.92 .

2. The infrared detector with a graded potential barrier of the nBn type according to claim 1, characterized in that The first electrode (7) is a Ti / Au electrode, and the second electrode (8) is a Ti / Au electrode.

3. An infrared detector with a graded potential barrier of the nBn type according to claim 1, characterized in that, The lower contact layer (3) is made of InAs 0.91 Sb 0.09 material, and the upper contact layer (6) is made of InAs 0.91 Sb 0.09 material.

4. The infrared detector with a graded barrier of the nBn type according to claim 1, characterized in that, The substrate (1) is made of GaSb material.

5. An infrared detector with a graded potential barrier of the nBn type according to claim 1, characterized in that, The buffer layer (2) is made of GaSb material.

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