Infrared detector and manufacturing method thereof

Abstract

The invention discloses an infrared detector, an absorption layer of the infrared detector is made of an N-type InAsSb material, and a barrier layer of the infrared detector is made of an InPSb material. The invention further discloses a manufacturing method of the infrared detector. In the infrared detector provided by the invention, the valence band of the InPSb barrier layer is flush with the valence band of the InAsSb absorption region to form an electron barrier, so that the dark current of the device can be inhibited, and the performance of the device can be improved.

Description

Technical Field

[0001] The present invention belongs to the fields of optoelectronics and semiconductor technologies, and more particularly, relates to an infrared detector and a method for manufacturing the same. Background Art

[0002] Infrared radiation detection is an important part of infrared technology and is widely used in fields such as thermal imaging, satellite remote sensing, gas monitoring, optical communication, and spectral analysis. The InAsSb alloy is an important infrared detection material. By changing the compositions of As and Sb, the absorption wavelength of InAsSb can cover the mid-wave band (3 - 5 μm) and the long-wave band (8 - 10 μm).

[0003] Figure 1 is a relationship diagram between the absorption wavelength of InAsSb and the Sb composition. Referring to Figure 1 , when the Sb composition is 0.63, the absorption wavelength of InAs 0.37 Sb 0.63 can reach 9 μm, and the corresponding bandwidth is only 0.138 eV, which is also the minimum bandwidth achievable by III - V compound semiconductor materials. And it is found that the minority carrier lifetime of InAsSb materials is much longer than that of type - II superlattices of antimonides with the same cut - off wavelength. Nevertheless, infrared detectors based on InAsSb materials are not commonly used, especially in the long - wave band. Among them, the main reason is that most of the existing InAsSb detectors are homojunctions, that is, PN junctions are all composed of InAsSb materials. Although such a structure is simple and easy to manufacture, it also results in a relatively high dark current in the device, including surface leakage current, generation - recombination current, and tunneling leakage current, etc.

[0004] Therefore, there is an urgent need to propose a new infrared detector structure and a method for manufacturing the same, so as to be able to utilize the excellent performance of InAsSb materials while improving the performance of the detector. Summary of the Invention

[0005] In order to solve the above - mentioned technical problems existing in the prior art, the present invention provides an infrared detector based on an InAsSb absorption layer and an InPSb barrier layer, and a method for manufacturing the same.

[0006] According to one aspect of the present invention, there is provided an infrared detector, wherein the absorption layer of the infrared detector is an N - type InAsSb material, and the barrier layer of the infrared detector is an InPSb material.

[0007] In an example of the infrared detector provided in the above - mentioned aspect, the lattice parameter of the absorption layer is greater than the lattice parameter of the substrate of the infrared detector, and the lattice parameter of the barrier layer is the same as the lattice parameter of the absorption layer.

[0008] In an example of the infrared detector provided in the above aspect, the infrared detector further includes a first contact layer, a second contact layer, a first electrode, and a second electrode; wherein, the first contact layer, the absorption layer, the barrier layer, and the second contact layer are sequentially stacked on the substrate in a direction away from the substrate, the first electrode is in contact with the first contact layer, and the second electrode is disposed on the second contact layer.

[0009] In an example of the infrared detector provided in the above aspect, a part of the absorption layer, the barrier layer, and the second contact layer is etched away to form a mesa structure exposing the first contact layer, and the first electrode is disposed on the exposed first contact layer.

[0010] In an example of the infrared detector provided in the above aspect, the substrate is an N-type InAs substrate or an N-type GaSb substrate, and / or the first contact layer is an N-type InAs material or an N-type InAsSb material, and / or the second contact layer is a P-type InPSb material.

[0011] According to another aspect of the present invention, a method for manufacturing an infrared detector is further provided. The manufacturing method includes: using an N-type InAsSb material to fabricate the absorption layer of the infrared detector, and using an InPSb material to fabricate the barrier layer of the infrared detector.

[0012] In an example of the manufacturing method provided in the above aspect, the lattice parameter of the absorption layer is greater than the lattice parameter of the substrate of the infrared detector, and the lattice parameter of the barrier layer is the same as the lattice parameter of the absorption layer.

[0013] In an example of the manufacturing method provided in the above aspect, before fabricating the absorption layer, the manufacturing method further includes: fabricating a first contact layer on the substrate; Wherein, using an N-type InAsSb material to fabricate the absorption layer of the infrared detector specifically includes: using an N-type InAsSb material to fabricate the absorption layer on the first contact layer; Wherein, using an InPSb material to fabricate the barrier layer of the infrared detector specifically includes: using an InPSb material to fabricate the barrier layer on the absorption layer; Wherein, after fabricating the barrier layer, the manufacturing method further includes: fabricating a second contact layer on the barrier layer; depositing a first electrode in contact with the first contact layer, and depositing a second electrode on the second contact layer.

[0014] In an example of the manufacturing method provided in the above aspect, depositing to form a first electrode in contact with the first contact layer specifically includes: locally etching the second contact layer, the barrier layer, and the absorption layer to form a mesa structure exposing the first contact layer; depositing and forming a first electrode on the exposed first contact layer.

[0015] In an example of the manufacturing method provided in the above aspect, the substrate is an N-type InAs substrate or an N-type GaSb substrate, and / or the first contact layer is an N-type InAs material or an N-type InAsSb material, and / or the second contact layer is an InPSb material.

[0016] Beneficial effects: The infrared detector of the present invention uses an InPSb material as the electron barrier layer of the InAsSb absorption layer to form a heterojunction device. Compared with the homojunction device of the prior art, it can effectively reduce the dark current of the device and improve the device performance. In addition, the Sb component of the InAsSb absorption layer in the infrared detector of the present invention can be arbitrarily adjusted to achieve detection in different bands, and the InPSb barrier layer can ensure the function of the electron barrier layer, that is, the valence bands are flush and the conduction bands are higher. Description of the Drawings

[0017] Through the following description in conjunction with the drawings, the above and other aspects, features, and advantages of the embodiments of the present invention will become clearer. In the drawings: Figure 1 is the relationship between the absorption wavelength and the Sb component of the InAsSb material; Figure 2 is the relationship diagram of the conduction band E c and valence band E v of InP, InAs, and InSb materials and their alloys with the lattice parameters of the materials, and the conduction band E c and valence band E v position diagram of InAsSb and InPSb according to the embodiments of the present invention; Figure 3 is the structural schematic diagram of the infrared detector according to the embodiments of the present invention; Figure 4 is the comparison of the 77K dark current data of the infrared detector using the InPSb / InAsSb heterojunction and the dark current data of the traditional infrared detector using the InAsSb / InAsSb homojunction in an embodiment of the present invention; Figures 5a to 5d is the process diagram of the manufacturing method of the infrared detector according to the embodiments of the present invention. Detailed Embodiments

[0018] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and should not be construed as limited to the specific embodiments set forth herein. On the contrary, these embodiments are provided to explain the principles of the present invention and its practical applications, so that other technical personnel in the art can understand various embodiments of the present invention and various modifications suitable for specific intended applications.

[0019] As used herein, the term "comprising" and its variants denote open terms, meaning "including but not limited to". Terms such as "based on", "according to", etc. mean "at least partially based on", "at least partially according to". Terms such as "embodiment", "an example", "one embodiment", and "an embodiment" mean "at least one embodiment". Terms such as "another embodiment", "another embodiment", "another example", "yet another example" mean "at least one other embodiment". Terms such as "first", "second", etc. may refer to different or the same objects. Other definitions may be included below, whether explicit or implicit. Unless explicitly specified in the context, the definition of a term is consistent throughout the specification.

[0020] Here, it should also be noted that in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the present invention are shown in the drawings, while other details of little relevance are omitted.

[0021] As described in the background art, existing InAsSb infrared detectors based on lattice mismatch are all based on homogeneous structures, with high dark currents and poor device performance, which limits their large-scale applications.

[0022] Therefore, in order to solve the above problems, an infrared detector and a manufacturing method thereof are provided according to an embodiment of the present invention. In this infrared detector, lattice-mismatched InAsSb is used as the absorption layer, and InPSb material is used as the electron barrier layer to form a heterojunction, and the lattice parameters of the InPSb barrier layer and the InAsSb absorption layer are the same. Figure 2 is the conduction band E of InP, InAs, and InSb materials and their alloys c and valence band E v versus the lattice parameter relationship diagram of the material. In Figure 2 the conduction band E of InPSb and InAsSb according to an embodiment of the present invention is marked c and valence band E v positions. First, taking InAsSb as an example, it can be seen that by increasing the Sb component in InAs, its lattice parameter will become larger, while the conduction band E c and valence band E vwill gradually increase until it changes to the energy band position of InSb. Secondly, it can be seen that for InAsSb with a fixed Sb composition (conduction band E c and valence band E v shown in red), for InPSb with the same lattice parameter as it (conduction band E c and valence band E v shown in blue), the valence band E v of InPSb is basically flush with the E v of InAsSb, while its conduction band E c is much higher than the E c of InAsSb, thus forming an ideal electron barrier. This is the core idea of the present invention. By forming an InPSb / InAsSb heterojunction with an electron barrier, compared with the InAsSb / InAsSb homojunction of the prior art, the dark current can be reduced and the device performance can be improved.

[0023] Figure 3 is a schematic structural diagram of an infrared detector according to an embodiment of the present invention.

[0024] Referring to Figure 3 shown, the infrared detector provided according to an embodiment of the present invention includes: a substrate 10; a first contact layer 11, an absorption layer 12, a barrier layer 13, and a second contact layer 14 stacked on the substrate 10 from bottom to top (i.e., stacked in sequence along the direction away from the substrate); and a first electrode 15 and a second electrode 16; wherein, the first electrode 15 is disposed on the first contact layer 11, and the second electrode 16 is disposed on the second contact layer 14.

[0025] In one example, the substrate 10 may be an N-type InAs substrate or an N-type GaSb substrate.

[0026] In one example, the first contact layer 11 may be made of N-type InAs or N-type InAsSb material, the thickness of the first contact layer 11 may be 0.2 µm to 0.5 µm, the doping source may be selected from Si or Te, and the doping concentration may be 1×10 18 cm -3 ~1×10 19 cm -3 .

[0027] In one example, the absorption layer 12 may be made of N-type InAsSb material, the thickness of the absorption layer 12 may be 2 µm to 5 µm, the doping source may be selected from Si or Te, and the doping concentration may be 1×10 15 cm -3 ~1×10 17 cm -3, the Sb component can be 0.2 to 0.8, corresponding to a bandwidth of 0.13 eV to 0.26 eV.

[0028] In one example, the barrier layer 13 can be made of InPSb material, the thickness of the barrier layer 13 can be 0.1 µm to 0.5 µm, undoped, and the lattice parameter of the barrier layer 13 is the same as that of the absorption layer 12.

[0029] In one example, the second contact layer 14 can be made of P-type InPSb material, the thickness of the second contact layer 14 can be 0.2 µm to 0.5 µm, the doping source can be selected from Zn or Be, and the doping concentration can be 1×10 18 cm -3 ~1×10 19 cm -3 , and the lattice parameter of the second contact layer 14 is the same as that of the barrier layer 13.

[0030] Figure 4 Device data of a specific embodiment of the present invention is provided. The absorption layer (12) of this device uses 2-µm-thick InAsSb material, and the barrier layer (13) uses a 200-nm-thick InPSb barrier layer to form an InPSb / InAsSb heterojunction. For comparison, an InAsSb / InAsSb PN homojunction composed of an absorption layer (12) of the same 2-µm-thick InAsSb material but without a barrier layer and only 200-nm P-type InAsSb is provided. It can be seen that when using the InPSb / InAsSb heterojunction, the dark current at 77 K is only 2.3×10 -6 A / cm 2 at a bias voltage of -0.1 V, while when using the traditional InAsSb / InAsSb homojunction, due to dark current mechanisms such as surface leakage current, generation-recombination current, and tunneling current, the total dark current is as high as 1.8×10 -3 A / cm 2 . Therefore, it can be seen that the InPSb barrier layer of the present invention has a great advantage over the traditional technology in suppressing dark current.

[0031] The manufacturing process of the infrared detector according to the embodiment of the present invention will be described in detail below. Figures 5a to 5d is a process diagram of the manufacturing method of the infrared detector according to the embodiment of the present invention.

[0032] Referring to Figure 5a , a substrate 10 is provided. In one example, the substrate 10 can be selected from an N-type InAs substrate or an N-type GaSb substrate.

[0033] Referring to Figure 5b, a stacked first contact layer 11, absorption layer 12, barrier layer 13, and second contact layer 14 are sequentially grown on the substrate 10 from bottom to top.

[0034] In one example, a first contact layer 11, an absorption layer 12, a barrier layer 13, and a second contact layer 14 are sequentially grown on the substrate 10 from bottom to top by using a metalorganic chemical vapor deposition (MOCVD) process. Specifically, taking metalorganic chemical vapor deposition MOCVD as the growth process, the growth sources are TMIn, TMSb, AsH 3 and PH 3 , the n-type doping source is SiH 4 , the p-type doping source is DEZn, the growth temperature is set at about 600 °C, and the reaction chamber pressure is set at 200 Torr. After removing the impurities on the surface of the substrate 10 by high-temperature treatment, the following are sequentially grown on the substrate 10 from bottom to top: (1) The first contact layer 11. In one example, the first contact layer 11 is an N-type InAs material with a thickness of 0.2 µm, doped with Si, and the doping concentration is 1×10 18 cm -3 .

[0035] (2) The absorption layer 12. In one example, the absorption layer 12 is an N-type InAsSb material with a thickness of 2 µm, doped with Si, and the doping concentration is 5×10 15 cm -3 , the Sb component is 0.23, the corresponding lattice parameter is 6.155 Å, and the corresponding bandwidth is 0.25 eV.

[0036] (3) The barrier layer 13. In one example, the barrier layer 13 is an InPSb material with a thickness of 0.1 µm, undoped, the Sb component is 0.47, the corresponding lattice parameter is 6.155 Å, and the corresponding bandwidth is 0.42 eV.

[0037] (4) The second contact layer 14. In one example, the second contact layer 14 is a P-type InPSb material with a thickness of 0.2 µm, doped with Zn, and the doping concentration is 1×10 18 cm -3 , the Sb component is 0.47, the corresponding lattice parameter is 6.155 Å, and the corresponding bandwidth is 0.42 eV.

[0038] Here, the MOCVD process is used as the growth process for the first contact layer 11, absorption layer 12, barrier layer 13, and second contact layer 14. The cut-off wavelength of the obtained infrared detector is about 5 µm, belonging to the mid-wave band. Since the MOCVD process has high productivity and low cost, using this process can reduce costs and improve the cost performance of the infrared detector.

[0039] In another example, the molecular beam epitaxy (MBE) process is used as the growth process. The growth sources are solid elemental sources In, As, Sb, and P, the n-type doping source is Te, and the p-type doping source is Be. The growth temperature is about 400 °C. After the substrate 10 is degassed and purified, the following layers are grown on the substrate 10 from bottom to top: (1) The first contact layer 11. In one example, the first contact layer 11 is an N-type InAsSb material with a thickness of 0.5 µm, doped with Te, and the doping concentration is 1×10 19 cm -3 , the Sb component is 0.09, and it is lattice-matched with the GaSb substrate.

[0040] (2) The absorption layer 12. In one example, the absorption layer 12 is an N-type InAsSb material with a thickness of 5 µm, doped with Te, and the doping concentration is 1×10 17 cm -3 , the Sb component is 0.63, the corresponding lattice parameter is 6.324 Å, and the corresponding bandgap is 0.138 eV.

[0041] (3) The barrier layer 13. In one example, the barrier layer 13 is an InPSb material with a thickness of 0.5 µm, undoped, the Sb component is 0.75, the corresponding lattice parameter is 6.324 Å, and the corresponding bandgap is 0.32 eV.

[0042] (4) The second contact layer 14. In one example, the second contact layer 14 is a P-type InPSb material with a thickness of 0.5 µm, doped with Be, and the doping concentration is 1×10 19 cm -3 , the corresponding lattice parameter is 6.324 Å, and the corresponding bandgap is 0.32 eV.

[0043] When the MBE process is used as the growth process, the cut-off wavelength of the obtained infrared detector is about 9 µm, belonging to the long-wave band. Since the MBE process can form a steep interface, the performance of the short-wave infrared detector obtained by this process is relatively high.

[0044] Referring to Figure 5c , local etching is performed on the second contact layer 14, the barrier layer 13, and the absorption layer 12 to form a mesa structure A that exposes the first contact layer 11.

[0045] In one example, an inductively coupled plasma etching (ICP) process is used to locally etch the second contact layer 14, the barrier layer 13, and the absorption layer 12 to expose the first contact layer 11, thereby forming the mesa structure A.

[0046] In another example, a wet etching process is used to locally etch the second contact layer 14, the barrier layer 13, and the absorption layer 12, exposing the first contact layer 11, thereby forming mesa structure A.

[0047] Referring to Figure 5d , a first electrode 15 is deposited on the first contact layer 11, and a second electrode 16 is deposited on the second contact layer 14.

[0048] In one example, an electron beam evaporation process is used to deposit the first electrode 15 on the exposed first contact layer 11 and deposit the second electrode 16 on the second contact layer 14. Among them, both the first electrode 15 and the second electrode 16 are Ti(500 Å) / Pt(500 Å) / Au(3000 Å) combinations.

[0049] In another example, an electron beam evaporation process is used to deposit the first electrode 15 on the exposed first contact layer 11 and deposit the second electrode 16 on the second contact layer 14. Among them, both the first electrode 15 and the second electrode 16 are Ti(200 Å) / Pt(400 Å) / Au(2000 Å) combinations.

[0050] In summary, according to the infrared detector and its manufacturing method of the embodiments of the present invention, the device structure adopts an InAsSb absorption region, the barrier layer adopts an InPSb material with the same lattice parameter, utilizes the natural characteristic that the conduction band of the InPSb material is higher and the valence band is flat, forms an ideal electron barrier, suppresses the dark current of the device, and improves the device performance. And the wavelength can cover the mid-wave to long-wave range, with a large adjustable range.

[0051] The terms "exemplary", "example", etc. used throughout this specification mean "serving as an example, instance, or illustration", and do not mean "preferred" or "having an advantage" over other embodiments. For the purpose of providing an understanding of the described technology, the specific embodiments include specific details. However, these technologies can be implemented without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described embodiments.

[0052] The above has described in detail the optional embodiments of the embodiments of the present invention in conjunction with the drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept scope of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0053] The foregoing description of the content of this specification is provided to enable any person of ordinary skill in the art to make or use the content of this specification. Various modifications to the content of this specification will be apparent to those of ordinary skill in the art, and the general principles defined herein can also be applied to other variations without departing from the scope of protection of the content of this specification. Therefore, the content of this specification is not limited to the examples and designs described herein, but is consistent with the broadest scope that conforms to the principles and novel features disclosed herein.

Claims

1. An infrared detector, characterized in that: The absorption layer of the infrared detector is made of N-type InAsSb material, and the barrier layer of the infrared detector is made of InPSb material.

2. The infrared detector according to claim 1, characterized in that: The lattice parameter of the absorption layer is greater than the lattice parameter of the substrate of the infrared detector, and the lattice parameter of the barrier layer is the same as the lattice parameter of the absorption layer.

3. The infrared detector according to claim 2, characterized in that: The infrared detector also includes a first contact layer, a second contact layer, a first electrode and a second electrode; wherein the first contact layer, the absorption layer, the barrier layer and the second contact layer are stacked in sequence on the substrate in a direction away from the substrate, the first electrode is in contact with the first contact layer, and the second electrode is arranged on the second contact layer.

4. The infrared detector according to claim 3, characterized in that: The absorption layer, the barrier layer, and a portion of the second contact layer are removed by etching to form a mesa structure exposing the first contact layer, and the first electrode is disposed on the exposed first contact layer.

5. The infrared detector according to claim 3, characterized in that: The substrate is an N-type InAs substrate or an N-type GaSb substrate, and / or the first contact layer is an N-type InAs material or an N-type InAsSb material, and / or the second contact layer is a P-type InPSb material.

6. A method for manufacturing an infrared detector, characterized in that: The manufacturing method comprises: using N-type InAsSb material to form an absorption layer of the infrared detector, and using InPSb material to form a barrier layer of the infrared detector.

7. The manufacturing method according to claim 6, characterized in that: The lattice parameter of the absorption layer is greater than the lattice parameter of the substrate of the infrared detector, and the lattice parameter of the barrier layer is the same as the lattice parameter of the absorption layer.

8. The production method according to claim 6 or 7, characterized in that: Before forming the absorption layer, the manufacturing method further includes: forming a first contact layer on the substrate; The method of using N-type InAsSb material to form the absorption layer of the infrared detector specifically includes: using N-type InAsSb material to form the absorption layer on the first contact layer; The use of InPSb material to form the barrier layer of the infrared detector specifically includes: using InPSb material to form the barrier layer on the absorption layer; After the barrier layer is formed, the manufacturing method further includes: forming a second contact layer on the barrier layer; depositing a first electrode in contact with the first contact layer, and depositing a second electrode on the second contact layer.

9. The manufacturing method according to claim 8, characterized in that: The depositing to form a first electrode in contact with the first contact layer specifically includes: Partially etching the second contact layer, the barrier layer, and the absorption layer to form a mesa structure exposing the first contact layer; A first electrode is deposited on the exposed first contact layer.

10. The manufacturing method according to claim 8, characterized in that: The substrate is an N-type InAs substrate or an N-type GaSb substrate, and / or the first contact layer is an N-type InAs material or an N-type InAsSb material, and / or the second contact layer is an InPSb material.

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