Infrared detector and method for manufacturing the 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, short-wave 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, making it widely applicable in many fields.

[0003] Common shortwave infrared detectors are primarily based on two materials: indium gallium arsenide (InGaAs) and mercury cadmium telluride (HgCdTe). InGaAs detectors offer superior performance at wavelengths below 1.7 μm. With the continued improvement of materials, the performance of InGaAs detectors is now comparable to that of HgCdTe detectors in the extended cutoff wavelength range (1.7 μm ≤ λc ≤ 2.5 μm). Antimonide-based shortwave infrared type-II superlattice (T2SL) technology has also been rapidly developed in recent years. In particular, the InP-based InGaAs / GaAsSb (indium gallium arsenide / gallium arsenide antimonide) T2SL not only responds to wavelengths below 2.5 μm, but also boasts superior dark current levels compared to HgCdTe at the same operating temperature. Considering performance, cost, manufacturability, etc., InGaAs detectors and InP-based T2SL detectors will become 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 P-type and N-type semiconductor layers). However, as application demands for extending the cutoff wavelength increase, it is necessary to increase the In content in the absorption layer. However, defects in In-rich InGaAs materials gradually increase, and the dominant mechanism for bulk dark current changes from diffusion to generation and recombination. At this time, depletion of the narrow bandgap absorption layer significantly increases the detector's dark current. For InP-based InGaAs / GaAsSb type-II superlattice detectors, suppressing generation and recombination in the absorption layer is also an important method for reducing dark current levels. 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 an intrinsic layer, a field control layer, and a blocking layer, which are sequentially adjacent to each other, the intrinsic layer being adjacent to the absorption layer and being a wide bandgap semiconductor material layer, and the field control layer and the blocking layer are both P-type doped wide bandgap semiconductor material layers.

[0007] A second aspect of the present invention is a method for manufacturing 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 bandgap semiconductor material on the second contact layer to form an absorption layer; forming a barrier composite layer by epitaxially growing an intrinsic layer, a field control layer, and a blocking layer on the absorption 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; epitaxially growing a first contact layer on the blocking layer. [Effects of the Invention]

[0008] In the infrared detector and fabrication method thereof provided in the above embodiments, the infrared detector mainly includes a first contact layer, a second contact layer, and an absorption layer and a barrier composite layer located between the first and second contact layers. The barrier composite layer includes an intrinsic layer, a field control layer, and a blocking layer, all of which are adjacent to each other and made of wide-bandgap semiconductor materials. The intrinsic layer is adjacent to the absorption layer, which is made of narrow-bandgap semiconductor materials. The absorption layer is N-doped, and the field control layer and the blocking layer are P-doped. The barrier composite layer and the absorption layer form a PIN structure, which shifts the depletion layer of the infrared detector into the wide-bandgap intrinsic layer and effectively suppresses the generation and recombination current of the detector. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an infrared detector according to some embodiments of the present application. [Figure 2] FIG. 2 is a schematic diagram of an infrared detector according to some embodiments of the present application. [Figure 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. [Figure 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. [Figures 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 INVENTION

[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 this application are only for the purpose of describing specific embodiments and are not intended to limit the implementation of this application. As used herein, the term "and / or" 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," and "outer" are orientations and positional relationships shown based on the drawings, and are merely for the convenience and simplification of the description of this application, and do not indicate or imply that the devices or elements referred to have a particular orientation or must be configured and operated in a particular 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] During research, the inventors of the present application discovered the above-mentioned problems with conventional extended-cutoff wavelength short-wavelength infrared detectors using PIN structures. Furthermore, they found that methods using nBn unipolar barrier structures to solve the dark current problem in InGaAs detectors and InP-based T2SL detectors were difficult to achieve due to limitations on the energy band type and the intrinsic background concentration level of the barrier layer, making it difficult to form an ideal unipolar barrier, and thus resulting in insignificant dark current reduction. Therefore, the inventors have proposed a new infrared detection structure that can be applied to short-wavelength infrared detection, particularly for extended-cutoff wavelength InGaAs detectors 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 by selecting appropriate materials.

[0014] Figures 1 to 3 and 5 each show schematic diagrams of an infrared detector according to a different embodiment of the present application, Figure 4 is a schematic diagram of the energy band sequence of the structure of an infrared detector 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 in 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 the manufacturing method thereof will be described in detail with reference to the above-mentioned 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. The barrier composite layer includes an intrinsic layer 500, a field control layer 600 and a blocking layer 700, which are sequentially adjacent to each other.

[0016] The intrinsic layer 500 is adjacent to the absorbing layer 400, i.e., located 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 greater than the bandgap of at least the incident energy.

[0017] The electric field control layer 600 is located on the opposite side of the intrinsic layer 500 from the absorption layer 400, and the intrinsic layer 500 includes opposing first and second sides, the second side contacting the first side of the absorption layer 400 and the first side adjacent to the electric field control layer 600. The electric field control layer 600 has an opposite doping type to that of the absorption layer 400 and is mainly used to prevent minority carriers in the absorption layer 400 from accumulating at the interface between the absorption layer 400 and the intrinsic layer 500. That is, the electric field control layer 600 removes or reduces the minority carrier barrier that exists at the interface between the absorption layer 400 and the intrinsic layer 500 and blocks or impedes the transport of minority carriers in the absorption layer 400, thereby preventing minority carriers in the absorption layer 400 from accumulating near the interface between the absorption layer 400 and the intrinsic layer 500.

[0018] The blocking layer 700 has the same doping type as the electric field control layer 600 and a doping concentration thereof is higher than that of the electric field control layer 600, i.e., the blocking layer 700 is highly doped and the electric field control layer 600 is lightly doped compared to the electric field control layer 600. 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 blocking layer 700 are P-type doping. The blocking layer 700 is intended to reduce the surface dark current of the detector, and a wide bandgap material must be selected.

[0019] It should be noted that 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 bandgap of the absorption layer 400 is less than the energy of the incident photons. The absorption layer 400 is a narrower bandgap semiconductor layer than the intrinsic layer 500, which is a wider bandgap semiconductor layer than the absorption layer 400. That is, the absorption layer 400 is a narrower bandgap semiconductor material layer, and the intrinsic layer 500, the field control layer 600, and the blocking layer 700 are all wide bandgap semiconductor material layers. In addition, in this application, the term "majority carriers" refers to either electrons or holes, and the term "minority carriers" refers to the other of electrons and holes. For example, in an N-type doped absorption layer, the majority carriers are electrons and the minority carriers are holes, while in 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, which are located on either side 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. As a result, a PIN structure is formed by the block layer, field control layer 600, intrinsic layer 500, and absorption layer 400. 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 forbidden band width of the intrinsic layer 500 is larger than the energy of the incident photon and is a wider bandgap material than the absorption layer 400, which effectively reduces the generation and recombination current of the infrared detector, i.e., reduces the dark current of the detector. The reason for this 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 intrinsic carrier concentration, which is inversely proportional to the forbidden band width. Therefore, in this application, the depletion layer can be completely shifted into the wide band gap intrinsic layer 500 through the PIN structure formed by the barrier composite layer and the absorption layer 400, thereby reducing the generation and recombination current. The field control layer adjacent to the intrinsic layer 500 is set to a low doping concentration, so that the doping process has almost no adverse effect on the intrinsic layer. It is also used to remove the minority carrier barrier formed at the interface between the intrinsic layer 500 and the absorption layer 400, preventing the accumulation of minority carriers at the interface between the intrinsic layer 500 and the absorption layer 400 and 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, thereby reducing 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 therefore is 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 of the present application, the absorption layer 400 is N-doped, and the field control layer 600 and the blocking layer 700 are both P-doped. Therefore, the infrared detector of the present application is a P-Bp-B2-N type infrared detector, where P in P-Bp-B2-N refers to the P-doped first contact layer 800, Bp in P-Bp-B2-N refers to the P-doped blocking layer 700, B2 refers to the double barrier layer formed by the field control layer 600 and the intrinsic layer 500, Bp-B2 in P-Bp-B2-N refers to the barrier composite layer of 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 the opposite doping type 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, because the Bp-B2 barrier composite layer is an electron barrier layer within the absorption layer 400, the P-Bp-B2-N 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 invention mainly includes a first contact layer, a second contact layer, an absorption layer, and a barrier composite layer located between the first and second contact layers. The barrier composite layer includes an intrinsic layer, a field control layer, and a blocking layer, all of which are adjacent to each other and made of wide-bandgap semiconductor materials. The intrinsic layer is adjacent to an absorption layer made of a narrow-bandgap semiconductor material. The absorption layer is N-doped, and the field control layer and blocking layer are P-doped. The barrier composite layer and the absorption layer form a PIN structure, which shifts the depletion layer of the infrared detector into the wide-bandgap intrinsic layer, suppresses generation and recombination currents in the detector, and effectively reduces the dark current of the infrared detector. Furthermore, the field control layer 600 effectively prevents minority carriers in the absorption layer 400 from accumulating in the intrinsic layer 500 and controls the charge distribution in the intrinsic layer 500, thereby further improving the detection performance of the infrared detector.

[0023] 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 has a first side and a second side opposite to each other, and 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 a higher doping concentration than the absorption layer 400. Therefore, the second contact layer 300 is a more heavily doped semiconductor layer than 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. Therefore, to prevent the incident photons from being absorbed by the other semiconductor layers before reaching the absorption layer 400, the band gaps of the buffer layer 200 and the second contact layer 300 must both be larger than the energy of the incident photons. Therefore, the buffer layer 200 and the second contact layer 300 are both wide band gap semiconductor material layers, and the substrate 100 is also made of a wide band gap semiconductor material, and its band gap 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 of the present invention. In FIG. 4, the ordinate represents the potential energy of the valence band upper end EV and the conduction band lower end EC, and the abscissa represents the thickness of each functional layer in 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 field control layer 600, and the conduction band minimum energy of the blocking layer 700 increase sequentially, i.e., 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 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, thereby optimizing the functions of each functional layer of the barrier composite layer. Therefore, in some embodiments, the forbidden band width of the blocking layer 700 is greater than the forbidden band width of the 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 larger than the energy of the incident photons.

[0027] 4 , minority carriers in the absorption layer 400 are transported into the first contact layer 800 via 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, which increases the lowest valence band upper end energy in the intrinsic layer 500 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, for example, 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 than the intrinsic layer 500.

[0029] In some embodiments, to further optimize the performance of the infrared detector according to the present disclosure, 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 relationships among the blocking layer 700, the electric field control layer 600, and the intrinsic layer 500 are not limited and can be adjusted according to the actual application needs.

[0030] 4, the dashed line in the field control layer and the intrinsic layer is the energy band of the intrinsic layer corresponding to a structure in which the barrier composite layer includes only the block layer and the intrinsic layer but does not include the field control layer, and it is clear that it is significantly recessed compared to the energy band of the intrinsic layer (solid line) when the field control layer is included. As a result, all of the minority carriers in the absorption layer are accumulated in this recess, which is unfavorable for the transport of minority carriers. Furthermore, if the field control layer is not added, in the case of a reverse bias, a tunnel breakdown phenomenon is likely to occur even on the side of the intrinsic layer close to the block layer. Figure 4 also schematically 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 a dashed line other than the dashed line in the same figure.

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

[0032] The P-Bp-B2-N type infrared detector of the present invention is suitable for InGaAs short-wave infrared detectors or InGaAs / GaAsSb type II superlattice short-wave infrared detectors, especially for extended wavelength InGaAs short-wave infrared detectors or InGaAs / GaAsSb type II superlattice short-wave infrared detectors, i.e., the In content 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 comprises In x Ga 1-x The absorption layer 400 is an N-type silicon (Si) or N-type silicon (S) doped with a low concentration of sulfur (S). - 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 absorption 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 thickness of the barrier layer is 4-7 nm, the range of the component y is 0.47≦y≦0.51, and the number of periods is 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 Al z Ga 1-z As y Sb 1-y layer, wherein 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 its background carrier concentration is 1 to 10E+15 cm -3 The absorption layer is the above-mentioned 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 absorber layer, i.e., the lattice mismatch between the intrinsic layer and the absorber 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, and its components are N - Mold Al z Ga 1-z As y Sb 1-y The thickness is 0.2 to 0.8 μm, and the doped acceptor concentration is 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 thickness of the layer is 0.5 to 2.0 μm, and the doped acceptor concentration is 0.5 to 2E+18 cm -3 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 + It is a wide band gap InP layer or InAlAs layer of the type, 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 bandgap semiconductor material layer, and may be, for example, at least one selected from an InAsP layer, an InP layer, and an InAlAs layer.

[0041] 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. A portion of the passivation layer 9012 is located on the opposite side of the first contact layer 800 from the block layer 700, and includes 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 in FIG. 8e) that passes through the first contact layer 800, the barrier composite layer, and the absorption layer 400 and terminates 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 with reference 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 the surface of the first contact layer 800 to the surface of the absorption layer 400, and the passivation layer 9012 extending 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 achieve the following beneficial effects. 1. By using a wide-bandgap Sb compound as a barrier and by introducing a double Sb compound barrier in the intrinsic layer and the field control layer, the depletion region can be shifted from the narrow-bandgap absorption layer to the wide-bandgap 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 within the barrier composite layer, the degree of freedom in 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 effectively suppresses surface dark current.

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

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

[0046] S2: Epitaxially growing an N-type doped narrow bandgap semiconductor material on the second contact layer to form an absorption 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, wherein the intrinsic layer is a wide bandgap semiconductor material layer, and the field control layer and the blocking layer are all 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 invention, 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 step S1, which differs from Fig. 6. Therefore, in this embodiment, step S1 specifically involves epitaxially growing a second contact layer on the buffer layer on the substrate.

[0050] Specifically, 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, i.e., 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 mesas bounded by mesa trenches.

[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 (blocking layer 700, field control layer 600, and 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 absorber layer 400 to form mesa trenches T2 as shown in FIG. 8b. The first contact layer 800 and the barrier composite layer formed in step S1 are partitioned by the mesa trenches T2 into multiple mesas located on the surface of the absorber 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 Figure 8c, a SiN film was formed on the surface of the intermediate structure of the infrared detector with the mesa. x Alternatively, an Al2O3 or SiO2 dielectric film is deposited to form a passivation layer 9012 covering the mesa, and the passivation layer also covers 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 a second type opening, and etch through the second type opening to form an electrode trench.

[0056] As shown in FIG. 8d, a second type opening T3 is formed on the passivation layer 9012 formed in S3 using a wet or dry etching process, and the second type opening exposes the area required for fabricating the second electrode 902. 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 of 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] The first electrode 903 and the second electrode 902 are fabricated using a Cr / Au or Ti / Pt / Au multilayer metal, with semi-ohmic contacts made with gold, to form an infrared detector 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 substitutions within the technical scope disclosed in the present application, and all such modifications and substitutions shall be considered to be within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be governed by 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, which are sequentially adjacent to each other, the intrinsic layer being adjacent to the absorbing layer and being a wide bandgap semiconductor material layer, the field control layer and the blocking layer being P-type doped wide bandgap semiconductor material layers; the field control layer is used to prevent minority carriers in the absorption layer from accumulating at the interface between the absorption layer and the intrinsic layer; An infrared detector, wherein the band gap of the blocking layer is larger than the band gap of the electric field control layer.

2. 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 the 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 bandgap 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 field control layer, and the conduction band minimum energy of the blocking layer increase sequentially, 4. The infrared detector according to claim 3, wherein the forbidden band width of said field control layer is equal to or greater than the forbidden band width 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 bandgap antimonide semiconductor material layers, and the antimony component in the intrinsic layer is lattice-matched to the absorption 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 Ga １－ｘ As layer or GaAs ｙ Sb １－ｙ layer, and the doped acceptor concentration of the first contact layer is 2E+18 cm －３ the thickness of the first contact layer is 0.05 to 0.2 μm; The absorption layer is made of silicon or sulfur doped In. ｘ Ga １－ｘ As layer, ｘ Ga １－ｘ The thickness of the As layer is 2.0 to 3.0 μm, or the absorption layer is In ０．５３ Ga ０．４７ As / GaAs ｙ Sb １－ｙ A type II superlattice layer, in which the In ０．５３ Ga ０．４７ As / GaAs ｙ Sb １－ｙ In type II superlattice layer 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 thickness of the barrier layer is 4 to 7 nm. ０．５３ Ga ０．４７ As / GaAs ｙ Sb １－ｙ the number of periods 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 Ga １－ｚ As ｙ Sb １－ｙ The intrinsic layer has a thickness of 0.3 to 1.0 μm and a background carrier concentration of 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, and the doped acceptor concentration of the blocking layer is 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 thickness of the second contact layer is 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 the opposite side of the first contact layer from the blocking layer, and has a first type opening and a second type opening; the first type opening exposes the first contact layer, and the second type opening exposes an electrode trench that passes through the first contact layer, the barrier composite layer, and the absorption layer in sequence 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 provided 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 the sidewalls and bottom of the mesa trench.

11. A method for producing an infrared detector according to claim 9, comprising the steps of: epitaxially growing a second contact layer on the substrate; epitaxially growing an N-type doped narrow bandgap semiconductor material on the second contact layer to form an absorption 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, and the field control layer and the blocking layer being P-type doped wide bandgap semiconductor material layers; epitaxially growing a first contact layer on the blocking layer.

12. Before 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; 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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