Infrared detector and method for making same

Abstract

The present invention provides an infrared detector and a method for fabricating the same. The infrared detector mainly includes a first contact layer (800), a second contact layer (300), an absorption layer (400) located between the first contact layer and the second contact layer, and a barrier composite layer. The barrier composite layer includes an intrinsic layer (500), an electric field control layer (600), and a blocking layer (700) which are adjacent to each other and are all made of wide band gap semiconductor materials, and the intrinsic layer is adjacent to the absorption layer which is made of narrow band gap semiconductor materials. The doping type of the absorption layer is N-type doped, and the electric field control layer and the blocking layer are both P-type doped, so that the barrier composite layer and the absorption layer form a PIN structure, which can shift the depletion layer of the infrared detector into the wide band gap intrinsic layer, and effectively suppress the generation and recombination current of the detector.

Description

[Technical field]

[0001] This application relates to the field of semiconductor technology, and more particularly to infrared detectors and methods for making same. [Background technology]

[0002] Compared with other wavelength detection, shortwave infrared detection has the ability to resolve details similar to visible light reflection imaging, while also having the ability to detect invisible light, giving it clear and irreplaceable imaging advantages and making it widely applicable in many fields.

[0003] Common shortwave infrared detectors are mainly made of two materials: InGaAs (indium gallium arsenide) and HgCdTe (mercury cadmium telluride). Among them, InGaAs detectors have excellent performance at wavelengths below 1.7 μm, and as the maturity of materials continues to improve, the performance of InGaAs detectors has already become comparable to that of HgCdTe detectors in the band range of extended cutoff wavelengths (1.7 μm≦λc≦2.5 μm). In addition, shortwave infrared type-II superlattice (T2SL) technology based on Sb (antimonide) has also been rapidly developed in recent years, and in particular, the InP-based InGaAs / GaAsSb (indium gallium arsenide / gallium arsenide antimonide)-based T2SL not only responds to the band below 2.5 μm, but its dark current level is already superior to that of HgCdTe at the same operating temperature. Considering all aspects including performance, cost, and manufacturability, InGaAs detectors and InP-based T2SL detectors will be the most valuable short-wave infrared detectors in the future.

[0004] In existing technology, InGaAs detectors often use a PIN structure (a structure in which an intrinsic semiconductor layer is sandwiched between a P-type semiconductor layer and an N-type semiconductor layer), but with the application demand of extending the cutoff wavelength, it is necessary to increase the In content in the absorption layer. However, the defects in In-rich InGaAs materials gradually increase, and the dominant mechanism of bulk dark current changes from diffusion to generation-recombination mechanism. At this time, when the narrow bandgap absorption layer is depleted, the dark current of the detector increases significantly. For InP-based InGaAs / GaAsSb type-II superlattice detectors, suppressing generation-recombination in the absorption layer is also an important method to reduce the dark current level. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the existing technical problems, embodiments of the present invention provide an infrared detector capable of reducing dark current and a method for fabricating the same. [Means for solving the problem]

[0006] A first aspect of an embodiment of the present invention provides an infrared detector, comprising a first contact layer, a second contact layer, and an absorption layer and a barrier composite layer located between the first contact layer and the second contact layer, the absorption layer is a layer of N-type doped narrow bandgap semiconductor material; An infrared detector is provided, wherein the barrier composite layer includes, in sequence, an intrinsic layer, a field control layer, and a blocking layer, the intrinsic layer being adjacent to the absorbing layer and being a layer of wide bandgap semiconductor material, and the field control layer and the blocking layer are both layers of P-type doped wide bandgap semiconductor material.

[0007] A second aspect of the present invention is a method for producing the infrared detector described above, comprising the steps of: epitaxially growing a second contact layer on the substrate; epitaxially growing an N-type doped narrow band gap semiconductor material on the second contact layer to form an absorbing layer; epitaxially growing an intrinsic layer, a field control layer, and a blocking layer on the absorption layer in sequence to form a barrier composite layer, the intrinsic layer being a wide bandgap semiconductor material layer, the field control layer and the blocking layer being P-type doped wide bandgap semiconductor material layers; and epitaxially growing a first contact layer on the blocking layer. Effect of the Invention

[0008] In the infrared detector and the fabrication method thereof according to the present application provided in the above embodiment, the infrared detector mainly includes a first contact layer, a second contact layer, an absorption layer and a barrier composite layer located between the first contact layer and the second contact layer. The barrier composite layer includes an intrinsic layer, a field control layer and a block layer, which are adjacent to each other and are all made of wide bandgap semiconductor materials, and the intrinsic layer is adjacent to the absorption layer, which is made of narrow bandgap semiconductor materials. The doping type of the absorption layer is N-type doped, and the field control layer and the block layer are both P-type doped, so that the barrier composite layer and the absorption layer form a PIN structure, which can move the depletion layer of the infrared detector into the wide bandgap intrinsic layer, and effectively suppress the generation and recombination current of the detector. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an infrared detector according to some embodiments of the present application. [Diagram 2] FIG. 2 is a schematic diagram of an infrared detector according to some embodiments of the present application. [Diagram 3] FIG. 3 is a schematic diagram of an infrared detector according to some embodiments of the present application. [Figure 4] FIG. 4 is a schematic diagram of an energy band sequence of an infrared detector according to some embodiments of the present application. [Diagram 5]FIG. 5 is a schematic diagram of an infrared detector according to some embodiments of the present application. [Figure 6] FIG. 6 is a schematic diagram of a manufacturing flow of an infrared detector according to some embodiments of the present application. [Figure 7] FIG. 7 is a schematic diagram of a manufacturing flow of an infrared detector according to some embodiments of the present application. [Figure 8a-8e] 8a to 8e are schematic diagrams of intermediate structures formed during the fabrication flow of an infrared detector according to some embodiments of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the technical aspects of the present application will be described in more detail with reference to the accompanying drawings and specific embodiments.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. The terms used herein in describing the present application are only intended to describe specific embodiments and are not intended to limit the implementation of the present application. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0012] In the description of this application, it should be understood that the orientations and positional relationships indicated by terms such as "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are orientations and positional relationships shown based on the drawings, and are merely for convenience and simplification of the description of this application, and do not indicate or imply that the devices or elements referred to have a specific orientation and must be constructed and operated in a specific orientation, and should not be understood as limiting the present disclosure. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0013] In the course of research, the inventors of the present application found that the conventional PIN structure-based extended wavelength short-wave infrared detectors have the above problems, and further found that the method of using the nBn unipolar barrier structure to solve the dark current problem of InGaAs detectors and InP-based T2SL detectors is difficult to form an ideal unipolar barrier due to the constraints of the energy band type and the intrinsic background concentration level of the barrier layer, and the dark current reduction effect is not significant. Therefore, the inventors of the present application have provided a new infrared detection structure that can be applied to short-wave infrared detection, and is particularly suitable for InGaAs detectors with extended cutoff wavelengths or InP-based InGaAs / GaAsSb type II superlattice detectors. Of course, the infrared detector of the present invention can also be applied to detectors of other wavelength types after selecting appropriate materials.

[0014] Figures 1 to 3 and 5 are schematic diagrams of infrared detectors according to different embodiments of the present application, Figure 4 is a schematic diagram of an energy band sequence of an infrared detector structure according to the present application, Figures 6 and 7 are schematic diagrams of a manufacturing flow of an infrared detector according to a different embodiment of the present application, and Figures 8a to 8e are schematic diagrams of each intermediate structure formed during the manufacturing flow of an infrared detector according to an embodiment of the present application. Hereinafter, the infrared detector according to the present application and its manufacturing method will be described in detail with reference to the above drawings.

[0015] 1, in some embodiments, the infrared detector includes a first contact layer 800, a second contact layer 300, an absorption layer 400 and a barrier composite layer located between the first contact layer 800 and the second contact layer 300. Among them, the barrier composite layer includes an intrinsic layer 500, a field control layer 600 and a blocking layer 700, which are adjacent to each other in sequence.

[0016] The intrinsic layer 500 is adjacent to the absorbing layer 400, i.e., on a first side of the absorbing layer 400, and the intrinsic layer 500 is a wide bandgap semiconductor material, i.e., its bandgap is at least greater than the bandgap of the incident energy.

[0017] The electric field control layer 600 is located on the opposite side of the intrinsic layer 500 from the absorbing layer 400, which includes opposing first and second sides, the second side of which contacts the first side of the absorbing layer 400, and the first side of which is adjacent to the electric field control layer 600. The electric field control layer 600 has an opposite doping type to that of the absorbing layer 400, and is mainly used to prevent minority carriers in the absorbing layer 400 from accumulating at the interface between the absorbing layer 400 and the intrinsic layer 500, i.e., the electric field control layer 600 is for removing or reducing a minority carrier barrier that exists at the interface between the absorbing layer 400 and the intrinsic layer 500 and blocks or impedes the transport of minority carriers in the absorbing layer 400, to prevent minority carriers in the absorbing layer 400 from accumulating near the interface between the absorbing layer 400 and the intrinsic layer 500.

[0018] The block layer 700 has the same doping type as the electric field control layer 600, and its doping concentration is higher than that of the electric field control layer 600, i.e., the block layer 700 is highly doped compared to the electric field control layer 600, and the electric field control layer 600 is lightly doped. The doping type of the absorption layer 400 is N-type doped, and the doping types of the electric field control layer 600 and the block layer 700 are P-type doped. The block layer 700 is for reducing the surface dark current of the detector, and a wide band gap material must be selected.

[0019] It should be explained that the photons in the incident light of the infrared detector enter the absorption layer 400 and are absorbed by the absorption layer 400, generating photo-generated carriers. Therefore, the band gap of the absorption layer 400 is equal to or less than the energy of the incident photon. The absorption layer 400 is a narrow band gap semiconductor layer compared to the intrinsic layer 500, and the intrinsic layer 500 is a wide band gap semiconductor layer compared to the absorption layer 400. That is, the absorption layer 400 is a narrow band gap semiconductor material layer, and the intrinsic layer 500, the electric field control layer 600, and the block layer 700 are all wide band gap semiconductor material layers. In addition, in this application, the majority carrier refers to one of electrons and holes, and the minority carrier refers to the other of electrons and holes. For example, for an N-type doped absorption layer, the majority carriers are electrons and the minority carriers are holes, and for a P-type doped absorption layer, the majority carriers are holes and the minority carriers are electrons.

[0020] The absorption layer 400 and the field control layer 600 located on both sides of the intrinsic layer 500 have different doping types, while the doping type of the block layer 700 is the same as that of the field control layer, so that a PIN structure is formed by the block layer, the field control layer 600, the intrinsic layer 500 and the absorption layer 400, and as can be seen from the principle of the PIN structure, the depletion layer of this structure is located in the middle intrinsic layer 500. The intrinsic layer 500 has a forbidden band width larger than the energy of the incident photon and is a wide band gap material compared to the absorption layer 400, so that it can effectively reduce the generation and recombination current of the infrared detector, i.e., reduce the dark current of the detector. The reason is that the generation and recombination mechanism mainly occurs in the depletion layer (space charge layer), and the generation and recombination current in the depletion layer is directly proportional to the concentration of intrinsic carriers, which is inversely proportional to the forbidden band width, so that in the present application, the depletion layer can be completely transferred into the wide band gap intrinsic layer 500 through the PIN structure formed by the barrier composite layer and the absorption layer 400, and as a result, the generation and recombination current can be reduced. And, the electric field control layer adjacent to the intrinsic layer 500 is set to be lightly doped, so that the doping process hardly has a negative effect on the intrinsic layer, and is also used to remove the minority carrier barrier formed at the interface between the intrinsic layer 500 and the absorption layer 400, which prevents the accumulation of minority carriers at the interface between the intrinsic layer 500 and the absorption layer 400, and is favorable for improving the transport of minority carriers in the absorption layer 400. Therefore, the electric field control layer 600 can improve the depletion layer barrier width on the side of the intrinsic layer 500 closer to the block layer 700, and reduce the probability of tunnel breakdown. On the other hand, the block layer 700 is farther from the intrinsic layer 400 than the electric field control layer 600, and is therefore highly doped with respect to the electric field control layer 600, and can effectively suppress leakage at the surface of the first contact layer 800.

[0021] In the infrared detector according to the present application, the doping type of the absorption layer 400 is N-type doping, and the doping types of the electric field control layer 600 and the block layer 700 are both P-type doping. Then, the infrared detector according to the present application is a P-Bp-B2-N type infrared detector, in which P in P-Bp-B2-N refers to the P-type doped first contact layer 800, Bp in P-Bp-B2-N refers to the P-type doped block layer 700, B2 refers to the double barrier layer composed of the electric field control layer 600 and the intrinsic layer 500, Bp-B2 in P-Bp-B2-N refers to the barrier composite layer according to the present application, and N in P-Bp-B2-N refers to the N-doped absorption layer 400. Therefore, in this embodiment, the majority carriers in the absorption layer 400 are electrons, and the minority carriers are holes. The Bp-B2 barrier composite layer includes an intrinsic layer adjacent to the absorption layer 400, and an electric field control layer 600 and a blocking layer 700 having a doping type opposite to that of the absorption layer 400, so that the P-Bp-B2-N structure has the function of a PIN structure, that is, the depletion layer is located completely within the intrinsic layer 500. And, since the Bp-B2 barrier composite layer is an electron barrier layer within the absorption layer 400, the P-Bp-B2-N type infrared detector also has the function of a PBN unipolar barrier structure (a structure in which an electron barrier B layer is provided between a P-type contact layer and an N-type absorption layer).

[0022] As can be seen from the above, the infrared detector according to the present application mainly includes a first contact layer, a second contact layer, an absorption layer and a barrier composite layer located between the first contact layer and the second contact layer. The barrier composite layer includes an intrinsic layer, an electric field control layer and a block layer, which are adjacent to each other and are all made of wide band gap semiconductor materials, and the intrinsic layer is adjacent to the absorption layer, which is made of a narrow band gap semiconductor material. The doping type of the absorption layer is N-type doped, and the electric field control layer and the block layer are both P-type doped, so that the barrier composite layer and the absorption layer form a PIN structure, which can shift the depletion layer of the infrared detector into the intrinsic layer of the wide band gap, suppress the generation and recombination current in the detector, and effectively reduce the dark current of the infrared detector. In addition, the electric field control layer 600 can effectively prevent the minority carriers in the absorption layer 400 from accumulating in the intrinsic layer 500, and can control the charge distribution in the intrinsic layer 500, thereby further improving the detection performance of the infrared detector.

[0023] In some embodiments, as shown in FIG. 2, the infrared detector according to the present application further includes a substrate 100 and a buffer layer 200. The buffer layer 200 is located between the substrate 100 and the second contact layer 300, specifically, the buffer layer 200 is located on one side of the substrate 100, for example, the substrate 100 includes a first side and a second side opposite to each other, the second side of the buffer layer 200 contacts the first side of the substrate 100, and the side of the buffer layer 200 opposite to the first side of the substrate 100 is the second side. The second contact layer 300 is located on the side of the buffer layer 200 opposite to the substrate 100, i.e., the second side of the buffer layer 200 contacts the second contact layer 300.

[0024] The second contact layer 300 has the same doping type as the absorption layer 400, and the doping concentration is higher than that of the absorption layer 400. Therefore, the second contact layer 300 is a highly doped semiconductor layer compared to the absorption layer 400, and the absorption layer 400 is a lightly doped semiconductor layer. In some embodiments, the second side of the substrate 100 is the incident side of the incident photons, i.e., the corresponding infrared detector is a back-illuminated infrared detector. Then, in order to prevent the incident photons from being absorbed by other semiconductor layers before being incident on the absorption layer 400, the forbidden band widths of the buffer layer 200 and the second contact layer 300 must both be larger than the energy of the incident photons, i.e., the buffer layer 200 and the second contact layer 300 are both wide bandgap semiconductor material layers, and the substrate 100 is also made of a wide bandgap semiconductor material, and the forbidden band width is also larger than the energy of the incident photons.

[0025] 4 is a schematic diagram of the energy band sequence of the first contact layer 800, the barrier composite layer, the absorption layer and the second contact layer in the P-Bp-B2-N type infrared detector according to the present application. In FIG. 4, the ordinate is the potential energy of the upper end EV of the valence band and the lower end EC of the conduction band, and the abscissa is the thickness of each functional layer of the P-Bp-B2-N type infrared detector.

[0026] 4, in some embodiments, the conduction band minimum energy of the intrinsic layer 500, the conduction band minimum energy of the electric field control layer 600, and the conduction band minimum energy of the blocking layer 700 increase sequentially, that is, the difference between the conduction band minimum energy of the intrinsic layer 500 and the conduction band minimum energy of the absorbing layer 400, the difference between the conduction band minimum energy of the electric field control layer 600 and the conduction band minimum energy of the absorbing layer 400, and the difference between the conduction band minimum energy of the blocking layer 700 and the conduction band minimum energy of the absorbing layer 400 increase sequentially, so that the functions of each functional layer of the barrier composite layer can be optimized respectively. Therefore, in some embodiments, the forbidden band width of the blocking layer 700 is greater than the forbidden band width of the electric field control layer 600 and the forbidden band width of the intrinsic layer 500, respectively. The intrinsic layer 500 and the blocking layer 600 are both made of wide bandgap materials compared to the absorbing layer 400, that is, the forbidden band widths of the intrinsic layer 500 and the blocking layer 600 must both be made larger than the energy of the incident photon.

[0027] 4, minority carriers in the absorption layer 400 are transported into the first contact layer 800 through the upper ends of the valence bands of the intrinsic layer 500, the electric field control layer 600, and the block layer 700 in that order. This is because the electric field control layer 600 can control the electric field in the intrinsic layer 500, and the lowest valence band upper end energy in the intrinsic layer 500 is increased compared to the valence band lower end energy of the absorption layer 400. This makes it possible to eliminate accumulation of minority carriers in the interface region between the absorption layer 400 and the intrinsic layer 500. As a result, minority carriers in the absorption layer 400 are transported into the first contact layer 800 smoothly passing through the upper ends of the valence bands of each layer.

[0028] Furthermore, in some embodiments, the first contact layer 800 is a narrow bandgap semiconductor material layer, e.g., the bandgap of the first contact layer 800 is smaller than the bandgap of the intrinsic layer 500, i.e., the first contact layer 800 is a narrower bandgap semiconductor material layer compared to the intrinsic layer 500.

[0029] In some embodiments, to further optimize the performance of the infrared detector according to the present application, the thickness of the blocking layer 700 may be designed to be equal to or greater than the thickness of the intrinsic layer 500, and the thickness of the intrinsic layer 500 may be designed to be equal to or greater than the thickness of the electric field control layer 600. However, it should be noted that in other embodiments, the thickness relationship between the blocking layer 700, the electric field control layer 600, and the intrinsic layer 500 is not limited and may be adjusted according to the actual application needs.

[0030] Referring to Fig. 4, the dashed line, which is a dashed line in the electric field control layer and the intrinsic layer, is the energy band of the intrinsic layer corresponding to the structure in which the barrier composite layer includes only the block layer and the intrinsic layer and does not include the electric field control layer, and it is clear that it is greatly recessed compared to the energy band of the intrinsic layer (solid line) when the electric field control layer is included, and as a result, all of the minority carriers in the absorption layer are accumulated in this recess, which is unfavorable to the transport of minority carriers, and if the electric field control layer is not added, in the case of reverse bias, the tunnel breakdown phenomenon is also likely to occur on the side of the intrinsic layer close to the block layer. Fig. 4 also shows the energy band structure of the intrinsic layer when a reverse bias voltage is applied to the P-Bp-B2-N type infrared detector of the present application, using another dashed line other than the dashed line in the figure.

[0031] As shown in FIG. 3, in some embodiments, the infrared detector according to the present application includes, from the substrate to the first contact layer, an InP substrate 100, a wide band gap buffer layer 200, a N + Type second contact layer 300, N - 400, a wide bandgap intrinsic layer 500, - Type electric field control layer 600, P + Mold block layer 700 and P + 8. The semiconductor device according to claim 7, further comprising a first contact layer 800. - is N + It is lightly doped compared to N + is N - It is highly doped compared to P - , P + It is lightly doped compared to P + , P- It is highly doped compared to

[0032] The P-Bp-B2-N type infrared detector of the present application is suitable for InGaAs short-wave infrared detectors or InGaAs / GaAsSb type II superlattice short-wave infrared detectors, especially suitable for extended wavelength InGaAs short-wave infrared detectors or InGaAs / GaAsSb type II superlattice short-wave infrared detectors, i.e. the content of In in the absorption layer is relatively high.

[0033] In some embodiments, the intrinsic layer 500 and the field control layer 600 are both layers of wide bandgap antimonide (Sb) semiconductor material, with the antimony content in the intrinsic layer being lattice matched to the absorbing layer.

[0034] Specifically, in some embodiments, the absorbing layer 400 is In x Ga 1-x The absorption layer 400 is an N-type Si (silicon) or S (sulfur) doped N-type As layer, where 0.47≦x≦0.82. - The absorption layer has a doped donor concentration of 0.5 to 5E+17 cm -3 and N - Type In x Ga 1-x The thickness of the As absorbing layer is 2.0 to 3.0 μm.

[0035] In some embodiments, the absorbing layer 400 comprises In 0.53 Ga 0.47 As / GaAs y Sb 1-y Type II superlattice layers, of which In 0.53 Ga 0.47 The thickness of the As well layer is 4 to 7 nm, and the GaAs y Sb 1-y The barrier layer has a thickness of 4-7 nm, a component y in the range of 0.47≦y≦0.51, and a periodic number of 150-300.

[0036] In some embodiments, the intrinsic layer 500 and the field control layer 600 are both Sb-containing compound semiconductor layers having a band gap greater than a predetermined value, that is, the intrinsic layer is a wide band gap semiconductor layer containing Sb.

[0037] Specifically, the intrinsic layer 500 is made of Al z Ga 1-z As y Sb 1-y layer, in which the range of Al content z is 0.2≦z≦0.5, the thickness of the intrinsic layer 500 is 0.3 to 1.0 μm, and the background carrier concentration thereof is 1 to 10E+15 cm -3 The absorption layer is the above In x Ga 1-x In the case of an As layer, the Sb content in the intrinsic layer 500 is adjusted to a predetermined content so as to ensure that the lattice is matched with the absorbing layer, i.e., the lattice mismatch between the intrinsic layer and the absorbing layer is lower than the maximum allowable mismatch.

[0038] Specifically, in some embodiments, the field control layer 600 is a lightly doped P - Mold Al z Ga 1-z As y Sb 1-y layer, the composition of which is N - Mold Al z Ga 1-z As y Sb 1-y The intrinsic layer has a thickness of 0.2 to 0.8 μm and a doped acceptor concentration of 0.5 to 5E+17 cm -3 In another embodiment, the field control layer may be a wide bandgap InP layer.

[0039] In some embodiments, the blocking layer 700 is at least one of an AlAsSb layer, an InAlAs layer, an InP layer, and an InAsP layer. Specifically, in this embodiment, the blocking layer 700 is a P + Type AlAs y Sb 1-yThe layer has a thickness of 0.5 to 2.0 μm and a doped acceptor concentration of 0.5 to 2E+18 cm -3 It is.

[0040] Continuing to refer to FIG. 3, specifically, in some embodiments, the first contact layer is P + Type In x Ga 1-x As layer or GaAs y Sb 1-y layer, the range of component y is 0.47≦y≦0.51, and its doped acceptor concentration is 2E+18 cm -3 The second contact layer 300 is made of N + The InP layer or InAlAs layer is a wide band gap type InP layer or InAlAs layer, which is highly doped with Si or S, and the doped donor concentration is 2 to 8E+18 cm -3 and its thickness is 0.2 to 1.0 μm. The substrate 100 is a single crystal N-type or semi-insulating InP substrate. The buffer layer 200 is a wide band gap semiconductor material layer, and may be, for example, at least one selected from an InAsP layer, an InP layer, and an InAlAs layer.

[0041] As shown in FIG. 5, in some embodiments, the infrared detector according to the present application further includes a passivation layer 9012, a first electrode 903, and a second electrode 902. The passivation layer 9012 is located on the opposite side of the first contact layer 800 from the block layer 700, and has a first type opening (e.g., T4 in FIG. 8e) and a second type opening (e.g., T3 in FIG. 8d). The first type opening exposes the first contact layer 800, and the second type opening exposes an electrode trench (e.g., the deep trench on the right side in FIG. 8e) that passes through the first contact layer 800, the barrier composite layer, and the absorption layer 400 and stops at the second contact layer 300. The first electrode 903 passes through the first type opening to form an ohmic contact with the first contact layer 800, and the second electrode 902 passes through the electrode trench to form an ohmic contact with the second contact layer 300. The passivation layer is made of SiN x , Al2O3, and SiO2, and the first electrode and the second electrode are both Cr / Au or Ti / Pt / Au multilayer metal electrodes.

[0042] Continuing to refer to FIG. 5, in some embodiments, the first contact layer 800 and the barrier composite layer are partitioned into multiple mesas in the absorption layer 400 by mesa trenches (e.g., T2 in FIG. 8b), the mesa trenches extending from a surface of the first contact layer 800 to a surface of the absorption layer 400, and the passivation layer 9012 extends from the side of the first contact layer 800 opposite the block layer 700 to the sidewalls and bottom of the mesa trenches, covering the exposed portions of the mesas and exposing only the first and second electrodes.

[0043] As can be seen from the above, the infrared detector according to each embodiment of the present application can provide the following beneficial effects. 1. By using a wide band gap Sb compound as a barrier and introducing a double Sb compound barrier in the intrinsic layer and the field control layer, the depletion region can be shifted from the narrow band gap absorption layer to the wide band gap barrier region, so that the absorption layer is dominated by the diffusion mechanism and the generation and recombination dark current in the bulk is significantly reduced. 2. By providing an electric field control layer in the barrier composite layer, the freedom of structural arrangement is improved, which not only improves the carrier collection efficiency but also effectively controls the tunnel breakdown dark current of the intrinsic layer as a depletion region. 3) The wide bandgap barrier composite layer design can effectively suppress surface dark current.

[0044] The present application further provides a method for fabricating an infrared detector according to an embodiment of the present application, a schematic flow diagram of which is shown in FIG. 6, in which the method for fabricating an infrared detector includes steps S1, S2, S3 and S4.

[0045] S1: A second contact layer is epitaxially grown on a substrate.

[0046] S2: Epitaxially grow an N-type doped narrow band gap semiconductor material on the second contact layer to form an absorbing layer.

[0047] S3: Sequentially epitaxially growing an intrinsic layer, a field control layer, and a blocking layer on the absorption layer to form a barrier composite layer, the intrinsic layer being a wide bandgap semiconductor material layer, and the field control layer and the blocking layer being P-type doped wide bandgap semiconductor material layers.

[0048] S4: A first contact layer is epitaxially grown on the blocking layer.

[0049] Fig. 7 is a schematic diagram of a method flow for fabricating an infrared detector according to another embodiment of the present application, and Figs. 8a to 8e can be referred to for intermediate structures formed in each step. In this embodiment, the fabrication method further includes step S0 of epitaxially growing a buffer layer on the substrate before S1, which is different from Fig. 6. Then, in this embodiment, S1 specifically means epitaxially growing a second contact layer on the buffer layer on the substrate.

[0050] Specifically, by using MOCVD (Metal-organic Chemical Vapor Deposition) or MBE (Molecular beam epitaxy) technology, each functional layer is epitaxially grown in sequence on an N-type or semi-insulating InP single crystal substrate, that is, a buffer layer, a second contact layer, an absorption layer, a barrier composite layer and a second contact layer are epitaxially grown in sequence on the substrate, thereby forming a structure as shown in FIG. 2.

[0051] Furthermore, still referring to FIG. 7, in this embodiment, in addition to S0 and S1 to S4 in FIG. 6, the fabrication method further includes S5 to S9 performed after S4, and each step is specifically as follows: S5: The first contact layer and the barrier composite layer are sequentially etched to form a mesa bounded by a mesa trench.

[0052] Specifically, as shown in FIG. 8a, first, an etching mask layer 9011 is formed on the surface of the first contact layer 800, and then, for example, a photoresist or SiO2, SiN xAn etching mask layer 9011 having an opening T1 is fabricated using a dielectric film, and the opening T1 exposes the region where the mesa trench is located. The first contact layer 800 and the barrier composite layer (the block layer 700, the electric field control layer 600, and the intrinsic layer 500) in the region where the mesa trench is located are sequentially etched and removed by wet or dry etching, and the etching is stopped at the surface of the absorption layer 400 to form a mesa trench T2 as shown in Fig. 8b. The first contact layer 800 and the barrier composite layer formed in S1 are partitioned by the mesa trench T2 into a plurality of mesas located on the surface of the absorption layer 400.

[0053] S6: A surface passivation process is performed on the mesa to form a passivation layer covering the mesa.

[0054] As shown in Fig. 8c, a SiN x Alternatively, an Al2O3 or SiO2 dielectric film is deposited to form a passivation layer 9012 covering the mesa, and the passivation layer is also covered on the absorption layer 400 exposed by the mesa trench T2, so that the surface of the intermediate structure of the infrared detector can be protected from oxidation, etc.

[0055] S7: Etch the passivation layer to form openings of a second type, and etch through the openings of the second type to form electrode trenches.

[0056] As shown in FIG. 8d, using a wet or dry etching process, a second type opening T3 is formed on the passivation layer 9012 formed in S3, and the second type opening exposes the area required for fabricating the second electrode 902, and then the area is etched to sequentially etch away the first contact layer 800, the barrier composite layer, and the absorption layer 400 corresponding to the area, and the etching is stopped within the second contact layer 300 to form an electrode trench.

[0057] S8: Etch the passivation layer to form a first type opening.

[0058] Using photolithography and wet or dry etching, a first type of opening T4 is formed on the passivation layer 9012 to expose the area required for fabricating the first electrode 903, as shown in FIG. 8e.

[0059] S9: A first electrode that forms an ohmic contact with the first contact layer, and a second electrode that forms an ohmic contact with the second contact layer are formed.

[0060] By fabricating the first electrode 903 and the second electrode 902 with semi-ohmic contacts by gold using Cr / Au or Ti / Pt / Au multi-layer metallurgy, an infrared detector is formed as shown in FIG.

[0061] The above are only specific embodiments of the present application, and the scope of protection of the present application is not limited thereto. Those skilled in the art can easily think of modifications and replacements within the technical scope disclosed in the present application, and all of these modifications and replacements should be within the scope of protection of the present application. Therefore, the scope of protection of the present application should be in accordance with the appended claims.

Claims

1. An infrared detector comprising: a first contact layer, a second contact layer, and an absorption layer and a barrier composite layer located between the first contact layer and the second contact layer; the absorption layer is a layer of N-type doped narrow bandgap semiconductor material; the barrier composite layer includes an intrinsic layer, a field control layer, and a blocking layer, successively adjacent to each other, the intrinsic layer being adjacent to the absorption layer and being a wide bandgap semiconductor material layer, the field control layer and the blocking layer being both P-type doped wide bandgap semiconductor material layers.

2. Further comprising a substrate and a buffer layer; the substrate is an N-type doped InP substrate or a semi-insulating InP substrate; the buffer layer is a layer of wide bandgap semiconductor material; 2. The infrared detector of claim 1, wherein the buffer layer is located between the second contact layer and the substrate, and the absorption layer is located on an opposite side of the second contact layer from the buffer layer.

3. the first contact layer is adjacent to the blocking layer and is a P-type doped narrow bandgap semiconductor material layer; 3. The infrared detector of claim 2, wherein the second contact layer is adjacent to the absorption layer and is an N-type doped wide band gap semiconductor material layer, and the doping concentration of the second contact layer is greater than the doping concentration of the absorption layer.

4. the conduction band minimum energy of the intrinsic layer, the conduction band minimum energy of the electric field control layer, and the conduction band minimum energy of the block layer increase in this order; 4. The infrared detector according to claim 3, wherein the band gap of said block layer is larger than the band gap of said electric field control layer, and the band gap of said electric field control layer is equal to or larger than the band gap of said intrinsic layer.

5. 2. The infrared detector of claim 1, wherein the absorption layer is an InGaAs layer or an InGaAs / GaAsSb type II superlattice layer.

6. 6. The infrared detector of claim 5, wherein the intrinsic layer and the field control layer are both wide band gap antimonide semiconductor material layers, and the antimony component in the intrinsic layer is lattice matched to the absorbing layer.

7. the intrinsic layer is an AlGaAsSb layer; the electric field control layer is an AlGaAsSb layer or an InP layer, the block layer is at least one of an AlAsSb layer, an InAlAs layer, an InP layer, and an InAsP layer; the first contact layer is an InGaAs layer or a GaAsSb layer; 7. The infrared detector according to claim 6, wherein the second contact layer is an InP layer or an InAlAs layer.

8. The first contact layer is In ｘ G １－ｘ As layer or GaAs ｙ Sb １－ｙ layer, the doped acceptor concentration of the first contact layer being 2E+18 cm －３ The first contact layer has a thickness of 0.05 to 0.2 μm. The absorption layer is made of In doped with silicon or sulfur. ｘ G １－ｘ As layer, and the In ｘ G １－ｘ The thickness of the As layer is 2.0 to 3.0 μm, or the absorption layer is In ０．５３ G ０．４７ As / GaAs ｙ Sb １－ｙ A type II superlattice layer, in which the In ０．５３ G ０．４７ As / GaAs ｙ Sb １－ｙ In type II superlattice layer ０．５３ G ０．４７ The thickness of the As well layer is 4 to 7 nm, and the GaAs ｙ Sb １－ｙ The thickness of the barrier layer is 4 to 7 nm. ０．５３ G ０．４７ As / GaAs ｙ Sb １－ｙ The periodic number of the type II superlattice layer is 150 to 300; The intrinsic layer and the electric field control layer are both made of Al. ｚ G １－ｚ A.S. ｙ Sb １－ｙ a thickness of the intrinsic layer is 0.3 to 1.0 μm, and a background carrier concentration of the intrinsic layer is 1 to 10E+15 cm －３ The thickness of the electric field control layer is 0.2 to 0.8 μm, and the doped acceptor concentration of the electric field control layer is 0.5 to 5E+17 cm －３ and The blocking layer is made of AlAs. ｙ Sb １－ｙ layer, the doped acceptor concentration of the blocking layer being 0.5 to 2E+18 cm －３ and the thickness of the blocking layer is 0.5 to 2.0 μm; The second contact layer is an InP layer or an InAlAs layer doped with silicon or sulfur, and the doped donor concentration of the second contact layer is 2 to 8E+18 cm －３ the second contact layer has a thickness of 0.2 to 1.0 μm; 8. The infrared detector according to claim 7, wherein the ranges of x, y and z are 0.47≦x≦0.82, 0.47≦y≦0.51 and 0.2≦z≦0.5, respectively.

9. further comprising a passivation layer, a first electrode, and a second electrode; the passivation layer is at least partially located on a side of the first contact layer opposite the blocking layer, and has a first type opening and a second type opening; the first type of opening exposes the first contact layer, and the second type of opening exposes an electrode trench that passes through the first contact layer, the barrier composite layer, the absorbing layer, and stops at the second contact layer; the first electrode passes through the first type opening and forms an ohmic contact with the first contact layer; 9. The infrared detector according to claim 1, wherein the second electrode passes through the electrode trench and forms an ohmic contact with the second contact layer.

10. the first contact layer and the barrier composite layer are partitioned into a plurality of mesas in the absorption layer by mesa trenches, the mesa trenches extending from a surface of the first contact layer to a surface of the absorption layer; 10. The infrared detector of claim 9, wherein the passivation layer extends from the side of the first contact layer opposite the blocking layer to a sidewall and a bottom of the mesa trench.

11. A method for producing the infrared detector according to claim 1, comprising the steps of: epitaxially growing a second contact layer on the substrate; epitaxially growing an N-type doped narrow band gap semiconductor material on the second contact layer to form an absorbing layer; epitaxially growing an intrinsic layer, a field control layer, and a blocking layer on the absorption layer to form a barrier composite layer, the intrinsic layer being a wide bandgap semiconductor material layer, the field control layer and the blocking layer being P-type doped wide bandgap semiconductor material layers; and epitaxially growing a first contact layer on the blocking layer.

12. Prior to epitaxially growing a second contact layer on the substrate, the method further comprises: further comprising epitaxially growing a buffer layer on the substrate; Epitaxially growing a second contact layer on the substrate includes: epitaxially growing a second contact layer on the buffer layer on the substrate; After epitaxially growing a first contact layer on the blocking layer, the method further comprises: Etching the first contact layer and the barrier composite layer to form a mesa bounded by a mesa trench; performing a surface passivation process on the mesa to form a passivation layer covering the mesa; Etching the passivation layer to form the second type openings and etching through the second type openings to form the electrode trenches; Etching the passivation layer to form the first type of opening; 12. The method of claim 11, further comprising forming a first electrode that forms an ohmic contact with the first contact layer, and a second electrode that forms an ohmic contact with the second contact layer.

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