WO2023141895A1 - 红外探测器及其制备方法 - Google Patents

红外探测器及其制备方法 Download PDF

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WO2023141895A1
WO2023141895A1 PCT/CN2022/074382 CN2022074382W WO2023141895A1 WO 2023141895 A1 WO2023141895 A1 WO 2023141895A1 CN 2022074382 W CN2022074382 W CN 2022074382W WO 2023141895 A1 WO2023141895 A1 WO 2023141895A1
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layer
contact
barrier
type
intrinsic
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PCT/CN2022/074382
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English (en)
French (fr)
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刘璐
周勋
詹雯慧
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成都英飞睿技术有限公司
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Priority to PCT/CN2022/074382 priority Critical patent/WO2023141895A1/zh
Publication of WO2023141895A1 publication Critical patent/WO2023141895A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/09—Devices sensitive to infrared, visible or ultraviolet radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
    • H01L31/105—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PIN type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof

Definitions

  • the present application relates to the field of semiconductor technology, in particular to an infrared detector and a preparation method thereof.
  • short-wave infrared detection not only has the ability to distinguish details similar to visible light reflective imaging, but also has the ability to detect invisible light. It has distinct and irreplaceable imaging advantages and can be widely used in many fields.
  • Common short-wave infrared detectors mainly include detectors based on two materials: InGaAs (indium gallium arsenide) and HgCdTe (mercury cadmium telluride).
  • InGaAs detectors perform well below 1.7 ⁇ m wavelength, and with the continuous improvement of material maturity, the performance of InGaAs detectors has been comparable to that of HgCdTe in the spectral range of extended cut-off wavelengths (1.7 ⁇ m ⁇ c ⁇ 2.5 ⁇ m). devices comparable.
  • T2SL short-wave infrared type-II superlattice
  • Sb antimony
  • 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 requirements of the extension of the cut-off wavelength, it is necessary to increase the amount of In in the absorbing layer. components.
  • PIN structure a structure in which an intrinsic semiconductor layer is sandwiched between a P-type semiconductor layer and an N-type semiconductor layer
  • the dominant mechanism of bulk dark current will change from diffusion to generation-recombination mechanism.
  • the depletion of the narrow bandgap absorber layer will cause the detector dark current to increase significantly.
  • suppressing generation-recombination in the absorber layer is also an important way to reduce the level of dark current.
  • an embodiment of the present invention provides an infrared detector capable of reducing dark current and a preparation method thereof.
  • the first aspect of the embodiment of the present invention provides an infrared detector, including a first contact layer, a second contact layer, and an absorption layer and a barrier composite layer between the first contact layer and the second contact layer;
  • the absorption layer is an N-type doped narrow bandgap semiconductor material layer
  • the barrier composite layer includes an intrinsic layer, a field control layer and a barrier layer adjacent in sequence, the intrinsic layer is adjacent to the absorption layer, and is a wide bandgap semiconductor material layer, the field control layer and the The barrier layers are P-type doped wide bandgap semiconductor material layers.
  • the intrinsic layer, the field control layer and the barrier layer are epitaxially grown in sequence on the absorption layer to form a barrier composite layer, the intrinsic layer is a wide bandgap semiconductor material layer, and the field control layer and the barrier layer are both P-type doped wide bandgap semiconductor material layer;
  • a first contact layer is epitaxially grown on the barrier layer.
  • the infrared detector mainly includes a first contact layer, a second contact layer, and an absorbing layer located between the first contact layer and the second contact and barrier composite layers.
  • the barrier recombination layer includes an intrinsic layer, a field control layer and a blocking layer which are adjacent in sequence and are all wide bandgap semiconductor materials, and the intrinsic layer is adjacent to the absorption layer of narrow bandgap semiconductor material.
  • the doping type of the absorption layer is N-type doping
  • the field control layer and the barrier layer are both P-type doping, so that the barrier recombination layer and the absorption layer can form a PIN structure, so that the depletion layer of the infrared detector can be transferred Into the intrinsic layer of the wide bandgap, the generation-recombination current of the detector is effectively suppressed.
  • Fig. 1 is a schematic diagram of an infrared detector according to some embodiments of the present application.
  • Fig. 2 is a schematic diagram of an infrared detector according to some embodiments of the present application.
  • Fig. 3 is a schematic diagram of an infrared detector according to some embodiments of the present application.
  • FIG. 4 is a schematic diagram of the energy band sequence of an infrared detector according to some embodiments of the present application.
  • Fig. 5 is a schematic diagram of an infrared detector provided according to some embodiments of the present application.
  • Fig. 6 is a schematic diagram of the preparation process of an infrared detector according to some embodiments of the present application.
  • Fig. 7 is a schematic diagram of the preparation process of an infrared detector according to some embodiments of the present application.
  • 8a to 8e are schematic diagrams of intermediate structures formed in the manufacturing process of the infrared detection device according to some embodiments of the present application.
  • the inventors of the present application found that the extended-wavelength short-wave infrared detector adopting the conventional PIN structure has the above-mentioned problems, and also found that the nBn unipolar barrier structure is used to solve the problem of the InGaAs detector and the InP-based T2SL detector.
  • the dark current problem due to the restriction of the energy band type and the intrinsic background concentration level of the barrier layer, it is difficult to form an ideal unipolar barrier, and the effect of reducing the dark current is not obvious.
  • the inventors of the present application provide a new infrared detection structure, which can be applied to short-wave infrared detection, especially suitable for InGaAs detectors with extended cut-off wavelengths or InP-based InGaAs/GaAsSb type II superlattice detectors.
  • the infrared detector provided by the present invention can also be applied to detectors of other wavelength types on the basis of selecting suitable materials.
  • Figures 1 to 3 and Figure 5 show schematic diagrams of infrared detectors according to different embodiments of the present application
  • Figure 4 is a schematic diagram of the energy band order of the structure of the infrared detector according to the present application, based on Figures 6 and 7
  • Figs. 8a to 8e are schematic diagrams of the intermediate structures formed in the manufacturing process of the infrared detecting device according to the embodiment of the present application.
  • the infrared detector provided by the present application and its preparation method will be described in detail below with reference to the above figures.
  • an infrared detector includes a first contact layer 800, a second contact layer 300, an absorbing layer 400 and a barrier compound between the first contact layer 800 and the second contact layer 300. layer.
  • the barrier composite layer includes an intrinsic layer 500 , a field control layer 600 and a barrier layer 700 adjacent in sequence.
  • the intrinsic layer 500 is adjacent to the absorbing layer 400 , that is, the intrinsic layer 500 is located on the first side of the absorbing layer 400 , and is a wide bandgap semiconductor material, that is, its forbidden band width is at least larger than that of the incident energy.
  • the field control layer 600 is located on the side of the intrinsic layer 500 facing away from the absorbing layer 400.
  • the intrinsic layer 500 has opposite first and second sides, the second side is in contact with the first side of the absorbing layer 400, and the first side is in contact with the absorbing layer 400. Adjacent to the field control layer 600 .
  • the field control layer 600 has an opposite doping type to that of the absorption layer 400, which is mainly used to prevent the accumulation of minority carriers in the absorption layer 400 at the interface between the absorption layer 400 and the intrinsic layer 500, that is, the field control layer 600 is used to eliminate or Reduce the minority carrier barrier existing at the interface between the absorbing layer 400 and the intrinsic layer 500 that blocks or impedes the transport of minority carriers in the absorbing layer 400, so as to avoid the minority carriers in the absorbing layer 400 at the interface between the absorbing layer 400 and the intrinsic layer 500 nearby accumulation.
  • the barrier layer 700 has the same doping type as the field control layer 600, and its doping concentration is greater than the doping concentration of the field control layer 600, that is, the barrier layer 700 is heavily doped relative to the field control layer 600, and the field control layer 600 is heavily doped. Layer 600 is lightly doped.
  • the doping type of the absorption layer 400 is N-type doping, and the doping type of the field control layer 600 and the blocking layer 700 is P-type doping.
  • the barrier layer 700 is used to reduce the surface dark current of the detector, which requires selection of a wide bandgap material.
  • the forbidden band width of the absorbing layer 400 is less than or equal to the energy of incident photons.
  • the absorption layer 400 is a narrow bandgap semiconductor layer relative to the intrinsic layer 500
  • the intrinsic layer 500 is a wide bandgap semiconductor layer relative to the absorption layer 400 . That is, the absorption layer 400 is a narrow bandgap semiconductor material layer, while the intrinsic layer 500 , the field control layer 600 and the barrier layer 700 are all wide bandgap semiconductor material layers.
  • the majority carrier in the present application refers to one of electrons and holes
  • the minority carrier refers to the other of electrons and holes.
  • the majority of carriers are electrons
  • the minority are holes
  • the majority of carriers are holes
  • the minority are electrons
  • the doping types of the absorption layer 400 and the field control layer 600 located on both sides of the intrinsic layer 500 are different, and the doping type of the barrier layer 700 is the same as that of the field control layer, then the barrier layer, the field control layer 600,
  • the intrinsic layer 500 and the absorption layer 400 constitute a PIN structure, and it can be known from the principle of the PIN structure that the depletion layer of the structure is located in the middle intrinsic layer 500 . Since the forbidden band width of the intrinsic layer 500 is greater than the energy of the incident photons, it is a wide-bandgap material relative to the absorbing layer 400, so it can effectively reduce the generation-recombination current of the infrared detector, that is, reduce the detector's dark current.
  • the generation-recombination mechanism mainly occurs in the depletion layer (space charge layer)
  • the generation-recombination current in the depletion layer is proportional to the concentration of intrinsic carriers
  • the concentration of intrinsic carriers is related to the forbidden band
  • the width is inversely proportional, so in this application, through the PIN structure formed by the barrier recombination layer and the absorber layer 400, all the depletion layer can be transferred to the wide bandgap intrinsic layer 500, thereby reducing the generation-recombination current.
  • the field control layer adjacent to the intrinsic layer 500 is set to be lightly doped, and the doping process has almost no adverse effect on the intrinsic layer, and it is also used to eliminate the formation of the interface between the intrinsic layer 500 and the absorption layer 400
  • the minority carrier barrier prevents the accumulation of minority carriers at the interface between the intrinsic layer 500 and the absorption layer 400, which is beneficial to improving the transport of minority carriers in the absorption layer 400. Therefore, the field control layer 600 can improve the barrier width of the depletion layer near the barrier layer 700 in the intrinsic layer 500 and reduce the probability of tunnel breakdown. Since the barrier layer 700 is far away from the intrinsic layer 400 relative to the field control layer 600 , it can be heavily doped relative to the field control layer 600 , which can effectively suppress leakage on the surface of the first contact layer 800 .
  • the doping type of the absorption layer 400 is N-type doping
  • the doping types of the field control layer 600 and the barrier layer 700 are both P-type doping.
  • the infrared detector provided by the present application is a P-Bp-B2-N type infrared detector, wherein, P in P-Bp-B2-N refers to the P-type doped first contact layer 800, and P-Bp- Bp in B2-N refers to the P-type doped barrier layer 700, B2 refers to the double barrier layer composed of field control layer 600 and intrinsic layer 500, then Bp-B2 in P-Bp-B2-N It is the barrier recombination layer provided in this application, and N in P-Bp-B2-N refers to the N-doped absorber layer 400 .
  • 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 absorber layer 400 and includes a field control layer 600 and a barrier layer 700 of the opposite doping type to the absorber layer 400, the P-Bp-B2-N structure has The function of the PIN structure, that is, the depletion layer is located entirely in the intrinsic layer 500 .
  • the Bp-B2 potential barrier composite layer is the electronic barrier layer in the absorption layer 400, so the P-Bp-B2-N type infrared detector also has a PBN unipolar barrier structure (the P-type contact layer and the N-type absorption layer There is an electronic barrier B layer) function between them.
  • 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 recombination layer includes an intrinsic layer, a field control layer and a blocking layer which are adjacent in sequence and are all wide bandgap semiconductor materials, and the intrinsic layer is adjacent to the absorption layer of narrow bandgap semiconductor material.
  • the doping type of the absorption layer is N-type doping
  • the field control layer and the barrier layer are both P-type doping, so that the barrier recombination layer and the absorption layer can form a PIN structure, so that the depletion layer of the infrared detector can be transferred Into the intrinsic layer of wide bandgap, effectively suppress the generation-recombination current in the detector, and the dark current of the infrared detector.
  • the field control layer 600 can effectively prevent the minority carriers in the absorption layer 400 from accumulating in the intrinsic layer 500, and at the same time can regulate the charge distribution in the intrinsic layer 500, further improving the detection performance of the infrared detector.
  • the infrared detector provided 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, such as the substrate 100 includes opposite first sides and second sides, the buffer layer 200
  • the second side of the buffer layer 200 is in contact with the first side of the substrate 100, and the side of the buffer layer 200 away from 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 facing away from the substrate 100 , that is, the second side of the buffer layer 200 is in contact with the second contact layer 300 .
  • the doping type of the second contact layer 300 is the same as that of the absorbing layer 400 , and its doping concentration is greater than that of the absorbing layer 400 . Therefore, the second contact layer 300 is a heavily doped semiconductor layer relative to the absorber layer 400 , while the absorber layer 400 is a lightly doped semiconductor layer.
  • the second side of the substrate 100 is the incident side of the incident photons, that is, the corresponding infrared detector is a back-illuminated infrared detector.
  • Each semiconductor layer absorbs, and the bandgap width of the buffer layer 200 and the second contact layer 300 is greater than the energy of the incident photon, that is, the buffer layer 200 and the second contact layer 300 are both wide-bandgap semiconductor material layers, and the substrate 100 is also Wide bandgap semiconductor materials have a forbidden band width greater than the energy of incident photons.
  • Fig. 4 is a schematic diagram of the energy band sequence of the first contact layer 800, the barrier recombination layer, the absorption layer and the second contact layer in the P-Bp-B2-N infrared detector provided by the present application.
  • the ordinate in Fig. 4 is the potential energy of the top EV of the valence band and the bottom EC of the conduction band, and the abscissa is the thickness of each functional layer of the P-Bp-B2-N infrared detector.
  • the bottom conduction band energy of the intrinsic layer 500, the bottom conduction band energy of the field control layer 600, and the bottom conduction band energy of the barrier layer 700 increase sequentially, that is, the conduction band bottom energy of the intrinsic layer 500
  • the difference between the bottom energy of the band and the bottom energy of the conduction band of the absorbing layer 400, the difference between the bottom energy of the conduction band of the field control layer 600 and the bottom of the conduction band of the absorbing layer 400, the energy of the bottom of the conduction band of the barrier layer 700 and the conduction of the absorbing layer 400 The energy difference at the bottom of the band increases sequentially, and the functions of each functional layer of the barrier compound layer can be optimized respectively.
  • the band gap of the blocking layer 700 is higher than both the band gap of the field control layer 600 and the band gap of the intrinsic layer 500 .
  • the intrinsic layer 500 and the barrier layer 600 are both wide-bandgap materials, that is, the band gaps of the intrinsic layer 500 and the barrier layer 600 must be greater than the energy of incident photons.
  • the minority carriers in the absorbing layer 400 are transported to the first contact layer 800 from the top of the valence band via the intrinsic layer 500 , the field control layer 600 , and the barrier layer 700 in sequence.
  • the field control layer 600 can regulate the electric field in the intrinsic layer 500, so that the energy of the lowest valence band top in the intrinsic layer 500 is increased relative to the energy of the valence band bottom of the absorbing layer 400, thereby eliminating the difference between the absorbing layer 400 and the intrinsic layer.
  • Minority carriers in the interface area of 500 are accumulated, so that the minority carriers in the absorbing layer 400 are smoothly transported to the first contact layer 400 through the top of the valence band of each layer.
  • the first contact layer 800 is a narrow bandgap semiconductor material layer, for example, the band gap of the first contact layer 800 is smaller than the band gap of the intrinsic layer 500, that is, the first contact layer 800 is smaller than the intrinsic layer 500. In terms of the feature layer 500, it is a narrow bandgap semiconductor material layer.
  • the thickness of the barrier layer 700 can be designed to be greater than or equal to the thickness of the intrinsic layer 500, and the thickness of the intrinsic layer 500 can be designed to be greater than or equal to It is equal to the thickness of the field control layer 600 .
  • the relationship between the thicknesses of the barrier layer 700, the field control layer 600, and the intrinsic layer 500 is not limited, and can be adjusted according to actual application requirements.
  • the dotted dashed line in the field control layer and the intrinsic layer is the energy band of the intrinsic layer corresponding to the structure of the barrier composite layer only including the barrier layer and the intrinsic layer but not including the field control layer, Obviously, it is more depressed than the energy band (solid line) of the intrinsic layer when there is a field control layer, which will cause the minority carriers in the absorption layer to be accumulated in this depression, which is not conducive to the minority carrier
  • the field control layer is not added, in the case of reverse bias, the side of the intrinsic layer close to the barrier layer is also prone to tunnel breakdown.
  • Figure 4 also shows the energy band structure of the intrinsic layer when the P-Bp-B2-N infrared detector provided by the present application is reversely biased, as shown in another non-dotted line in Figure 5 .
  • the infrared detector provided by the present application includes an InP substrate 100, a wide bandgap buffer layer 200, and an N + -type second contact layer 300 sequentially from the substrate direction to the first contact layer direction.
  • N - type absorption layer 400 wide bandgap intrinsic layer 500 , P - type field control layer 600 , P + type barrier layer 700 and P + type first contact layer 800 .
  • N- is lightly doped relative to N +
  • N + is heavily doped relative to N-
  • P- is lightly doped relative to P +
  • P + is relatively P - is heavily doped.
  • the P-Bp-B2-N infrared detector provided by this 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/ In GaAsSb type II superlattice shortwave infrared detectors, the composition of In in the absorbing layer is relatively high.
  • both the intrinsic layer 500 and the field control layer 600 are wide bandgap antimony (Sb) compound semiconductor material layers, and the antimony component in the intrinsic layer matches the lattice of the absorption layer.
  • the absorption layer 400 is an In x Ga 1-x As layer, where 0.47 ⁇ x ⁇ 0.82.
  • the absorber layer 400 is an N - type absorber layer lightly doped with N-type Si (silicon) or S (sulfur), the doped donor concentration is 0.5-5E+17cm -3 , and the N - type In x Ga 1-x As absorbs
  • the thickness of the layer is 2.0-3.0 ⁇ m.
  • the absorbing layer 400 is a In 0.53 Ga 0.47 As/GaAs y Sb 1-y type II superlattice layer, wherein the thickness of the In 0.53 Ga 0.47 As well layer is 4-7 nm, and the GaAs y Sb 1-y The thickness of the barrier layer is 4-7nm, the range of composition y is: 0.47 ⁇ y ⁇ 0.51, and the period number is 150-300.
  • both the intrinsic layer 500 and the field control layer 600 are Sb-containing compound semiconductor layers with a bandgap greater than a predetermined value, that is, the intrinsic layer is a broadband semiconductor layer containing Sb.
  • the intrinsic layer 500 is an Al z Ga 1-z As y Sb 1-y layer, wherein the range of the Al composition z is: 0.2 ⁇ z ⁇ 0.5, and the thickness of the intrinsic layer 500 is 0.3-1.0 ⁇ m, And its background carrier concentration is 1-10E+15cm -3 .
  • the absorbing layer is the above-mentioned In x Ga 1-x As layer
  • adjust the Sb component in the intrinsic layer 500 to a preset composition so that it matches the lattice with the absorbing layer, that is, ensures the gap between the intrinsic layer and the absorbing layer.
  • the lattice mismatch rate between them is lower than the maximum allowable mismatch rate.
  • the field control layer 600 is a lightly doped p -type Al z Ga 1-z As y Sb 1-y layer, whose composition is the same as that of an N -type Al z Ga 1-z As y
  • the Sb 1-y intrinsic layer is the same, but its thickness is 0.2-0.8 ⁇ m, and the doping acceptor concentration is 0.5-5E+17 cm ⁇ 3 .
  • the field control layer may also be an InP layer with a wide band gap.
  • the barrier layer 700 is at least one of an AlAsSb layer, an InAlAs layer, an InP layer, and an InAsP layer.
  • the barrier layer 700 is a P+ type AlAsySb 1-y layer, Its thickness is 0.5-2.0 ⁇ m, and the doping acceptor concentration is 0.5-2E+18cm -3 .
  • the first contact layer is a P + type In x Ga 1-x As layer or a GaAs y Sb 1-y layer, and the composition y ranges from: 0.47 ⁇ y ⁇ 0.51, its doping acceptor concentration ⁇ 2E+18cm -3 , and its thickness is 0.05-0.2 ⁇ m.
  • the second contact layer 300 is an N+ type wide bandgap InP layer or InAlAs layer, which is heavily doped with Si or S, with a doping donor concentration of 2-8E+18cm ⁇ 3 , and a thickness of 0.2-1.0 ⁇ m.
  • 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, for example, it may be selected from at least one of an InAsP layer, an InP layer, and an InAlAs layer.
  • the infrared detector provided according to the present application further includes a passivation layer 9012 , a first electrode 903 , and a second electrode 902 .
  • a part of the passivation layer 9012 is located on the side of the first contact layer 800 facing away from the barrier layer 700, and has a first type of opening (such as T4 in FIG. 8e) and a second type of opening (such as T3 in FIG. 8d).
  • the first type of opening exposes the first contact layer 800
  • the second type of opening exposes the electrode groove that passes through the first contact layer 800, the barrier composite layer, and the absorption layer 400 in sequence and stops at the second contact layer 300 (as shown in FIG. 8e deep groove on the right).
  • the first electrode 904 forms an ohmic contact with the first contact layer 800 through the first type of opening; the second electrode 300 forms an ohmic contact with the second contact layer 300 through the electrode groove.
  • the passivation layer is selected from at least one of SiN x , Al 2 O 3 , and SiO 2 , and both the first electrode and the second electrode are Cr/Au or Ti/Pt/Au multilayer metal electrodes.
  • the first contact layer 800 and the barrier composite layer are separated into a plurality of mesas arranged on the absorption layer 400 by mesa grooves (T2 in FIG. 8 b ), and the mesas
  • the trench extends from the surface of the first contact layer 800 to the surface of the absorption layer 400, and the passivation layer 9012 extends from the side of the first contact layer 800 facing away from the barrier layer 700 to the sidewall and bottom of the mesa trench, thereby exposing the mesa
  • the outer part is wrapped, and only the first electrode and the second electrode are exposed.
  • the degree of freedom of structure modulation is improved, which can not only improve the carrier collection efficiency, but also effectively control the tunnel breakdown dark current of the intrinsic layer as the depletion region.
  • the design of the barrier composite layer with wide bandgap can effectively suppress the surface dark current.
  • the present application also provides a preparation method of an infrared detector according to an embodiment of the present application.
  • the schematic flow chart of the preparation method is shown in Figure 6.
  • the preparation method includes S1, S2, S3 and S4.
  • S1 epitaxially growing a second contact layer on the substrate.
  • S2 epitaxially growing an N-type doped narrow bandgap semiconductor material on the second contact to form an absorption layer.
  • S3 sequentially epitaxially grow an intrinsic layer, a field control layer and a barrier layer on the absorption layer to form a barrier composite layer, the intrinsic layer is a wide bandgap semiconductor material layer, the field control layer and the barrier layer Both are P-type doped wide bandgap semiconductor material layers.
  • FIG. 7 is a schematic flowchart of a method for manufacturing an infrared detector according to another embodiment of the present application, and the intermediate structures formed in each step can be referred to in FIGS. 8a-8e.
  • the preparation method further includes S0: epitaxially growing a buffer layer on the substrate.
  • S1 specifically includes: epitaxially growing the second contact layer on the buffer layer on the substrate.
  • MOCVD Metal-organic Chemical Vapor Deposition, metal organic compound chemical vapor deposition
  • MBE Molecular beam epitaxy, molecular beam epitaxy
  • the functional layer that is, the structure formed by sequentially epitaxially growing a buffer layer, a second contact layer, an absorber layer, a barrier compound layer and a second contact layer on the substrate is shown in FIG. 2 .
  • the preparation method further includes S5 to S9 performed after S4, and each step is specifically as follows:
  • an etching mask layer 9011 is first formed on the surface of the first contact layer 800, such as using photoresist or SiO 2 , SiN x dielectric film to make an etching mask layer 901 with an opening T1 , the opening T1 exposes the area where the terrace surface groove is located.
  • the first contact layer 800 and the barrier compound layer (barrier layer 700, field control layer 600, intrinsic layer 500) in the area where the mesa groove is located are sequentially etched away by wet or dry etching, and the etching is stopped. on the surface of the absorbing layer 400, thereby forming a mesa trench T2 as shown in FIG. .
  • a SiN x or Al 2 O 3 , SiO 2 dielectric film is deposited on the surface of the infrared detector intermediate structure forming the mesa to form a passivation layer 9012 that wraps the mesa, and the passivation layer also covers the mesa groove
  • the groove T2 is exposed on the absorbing layer 400, thereby protecting the surface of the intermediate structure of the infrared detector from being oxidized.
  • S7 Etching the passivation layer to form a second type of opening, and etching through the second type of opening to form an electrode groove.
  • a second type of opening T3 is formed on the passivation layer 9012 formed in S3 by using a wet or dry etching process, so that the second type of opening exposes the area where the second electrode 902 needs to be formed, and then etched. region, etch away the corresponding first contact layer 800, barrier compound layer, and absorber layer 400 in sequence, and stop the etching in the second contact layer 300, so as to form electrode trenches.
  • a first type of opening T4 is formed on the passivation layer 9012 by means of photolithography and wet or dry etching, so as to expose the area where the first electrode 903 needs to be formed.
  • the first electrode 903 and the second electrode 902 of the gold-semi-ohmic contact are made of Cr/Au or Ti/Pt/Au multilayer metal, thereby forming an infrared detector as shown in FIG. 5 .

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Abstract

提供一种红外探测器及其制备方法，红外探测器主要包括第一接触层（800）、第二接触层（300）以及位于第一接触层与第二接触层之间的吸收层（400）和势垒复合层。其中，势垒复合层包括依次相邻且均为宽带隙半导体材料的本征层（500）、场控层（600）和阻挡层（700），本征层与窄带隙半导体材料的吸收层相邻。且吸收层的掺杂类型为N型掺杂，而场控层和阻挡层均为P型掺杂，从而可使势垒复合层与吸收层形成PIN结构，使得红外探测器的耗尽层转移到宽带隙的本征层中，有效地抑制了探测器的产生-复合电流。

Description

红外探测器及其制备方法 技术领域
本申请涉及半导体技术领域，尤其涉及一种红外探测器及其制备方法。
背景技术
短波红外探测相对于其他波长探测而言，既具有类似可见光反射式成像可分辨细节的能力，又具有不可见光探测能力，具有鲜明的不可替代的成像优势，可广泛应用于众多领域。
常见的短波红外探测器主要有基于InGaAs(铟镓砷)、HgCdTe(碲镉汞)两种材料制备的探测器。其中，InGaAs探测器在1.7μm波长以下表现优异，且随着材料成熟度不断提升，在延伸截止波长(1.7μm≤λc≤2.5μm)的谱段范围，InGaAs探测器的性能已经可与HgCdTe探测器相媲美。此外，基于Sb(锑)化物的短波红外二类超晶格(type-II superlattice，T2SL)技术近年来也发展较为快速，尤其是InP基InGaAs/GaAsSb(铟镓砷/镓砷锑)体系T2SL，不仅能够响应2.5μm以下谱段，而且其暗电流水平已优于相同工作温度的HgCdTe。从性能、成本、可制造性等因素综合考量，InGaAs探测器以及InP基T2SL探测器将成为最有应用价值的短波红外探测器。
现有技术中，InGaAs探测器常采用PIN结构(P型半导体层和N型半导体层夹有本征半导体层的结构)，但随着截止波长延伸的应用需求，需要增加吸收层中的In的组分。然而，高In组分InGaAs材料的缺陷逐渐增多，体暗电流主导机制将由扩散转变为产生-复合机制，此时，窄带隙的吸收层在耗尽后将造成探测器暗电流显著增大。而对于InP基InGaAs/GaAsSb二类超晶格探测器而言，抑制吸收层内的产生-复合同样是降低暗电流水平的重要途径。
技术问题
为了解决现有存在的技术问题，本发明实施例提供一种可降低暗电流的红外探测器及其制备方法。
技术解决方案
本发明实施例第一方面，提供一种红外探测器，包括第一接触层、第二接 触层以及位于所述第一接触层和第二接触层之间的吸收层和势垒复合层；
所述吸收层为N型掺杂的窄带隙半导体材料层；
所述势垒复合层包括依次相邻的本征层、场控层以及阻挡层，所述本征层与所述吸收层相邻，且为宽带隙半导体材料层，所述场控层和所述阻挡层均为P型掺杂的宽带隙半导体材料层。
本发明实施例第一方面，提供一种如所述红外探测器的制备方法，包括:
在衬底上外延生长第二接触层；
在所述第二接触上外延生长N型掺杂的窄带隙半导体材料，形成吸收层；
在所述吸收层上依次外延生长本征层、场控层以及阻挡层，形成势垒复合层，所述本征层为宽带隙半导体材料层，所述场控层和所述阻挡层均为P型掺杂的宽带隙半导体材料层；
在所述阻挡层上外延生长第一接触层。
有益效果
上述实施例所提供的本申请提供的红外探测器及其制备方法中，红外探测器主要包括第一接触层、第二接触层以及位于所述第一接触层与第二接触之间的吸收层和势垒复合层。其中，势垒复合层包括依次相邻且均为宽带隙半导体材料的的本征层、场控层和阻挡层，本征层与窄带隙半导体材料的吸收层相邻。且吸收层的掺杂类型为N型掺杂，而场控层和阻挡层均为P型掺杂，从而可使势垒复合层与吸收层形成PIN结构，使得红外探测器的耗尽层转移到宽带隙的本征层中，有效的抑制了探测器的产生-复合电流。
附图说明
图1为依据本申请一些实施例的红外探测器示意图；
图2为依据本申请一些实施例的红外探测器示意图；
图3为依据本申请一些实施例的红外探测器示意图；
图4为依据本申请一些实施例的红外探测器的能带次序示意图；
图5为依据本申请一些实施例提供的红外探测器示意图；
图6为依据本申请一些实施例的红外探测器的制备流程示意图；
图7为依据本申请一些实施例的红外探测器的制备流程示意图；
图8a至8e为依据本申请一些实施例的红外探测器件的制备流程中形成的各中间结构示意图。
本发明的实施方式
以下结合说明书附图及具体实施例对本申请技术方案做进一步的详细阐述。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。本文中在本申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请的实现方式。本文所使用的术语“及/或”包括一个或多个相关的所列项目的任意的和所有的组合。
在本申请的描述中，需要理解的是，术语“中心”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。在本申请的描述中，除非另有说明，“多个”的含义是两个或两个以上。
本申请的发明人在研究的过程中，发现采用常规的PIN结构的延伸波长短波红外探测器存在上述的问题，还发现采用nBn单极势垒结构来解决InGaAs探测器以及InP基T2SL探测器的暗电流问题的方式，由于能带类型以及势垒层本征背景浓度水平的制约，难以形成理想的单极势垒，降低暗电流的效果不明显。因此，本申请发明人提供了一种新的红外探测结构，其可应用于短波红外探测，尤其适合延伸截止波长的InGaAs探测器或InP基InGaAs/GaAsSb二类超晶格探测器。当然，本发明提供的红外探测器在选择合适材料的基础上，也可应用于其它波长类型的探测器。
图1至图3以及图5分示出了依据本申请的不同实施例的红外探测器示意图，图4为依据本申请的红外探测器的结构的能带次序示意图，图6与图7为依据本申请的不同实施例的红外探测器的制备流程示意图，图8a至8e为依据本申请实施例的红外探测器件的制备流程中形成的各中间结构示意图。下面将结合上述各图具体阐述本申请提供的红外探测器及其制备方法。
参考图1所示，在一些实施例中，红外探测器包括第一接触层800、第二接触层300以及位于第一接触层800和第二接触层300之间的吸收层400和势 垒复合层。其中，该势垒复合层包括依次相邻的本征层500、场控层600以及阻挡层700。
本征层500与吸收层400相邻，即本征层500位于吸收层400的第一侧，其为宽带隙半导体材料，即其禁带宽度至少要大于入射能量的禁带宽度。
场控层600位于本征层500背离吸收层400的一侧，本征层500具有相对的第一侧和第二侧，其第二侧与吸收层400的第一侧接触，其第一侧与场控层600相邻。场控层600具有与吸收层400相反的掺杂类型，其主要用于阻止吸收层400中的少子在吸收层400与本征层500交界面处的累积，即场控层600用于消除或降低吸收层400与本征层500的交界面处存在的阻挡或阻碍吸收层400中的少子运输的少子势垒，以避免吸收层400中的少子在吸收层400与本征层500交界面处附近的累积。
阻挡层700具有与场控层600相同的掺杂类型，且其掺杂浓度大于场控层600的掺杂浓度，即阻挡层700相对于场控层600而言为重掺杂，而场控层600为轻掺杂。吸收层400的掺杂类型为N型掺杂，场控层600与阻挡层700的掺杂类型为P型掺杂。阻挡层700用于减少探测器的表面暗电流，其需要选择宽禁带材料。
需要说明的是，红外探测器的入射光中的光子进入吸收层400后会被吸收层400吸收，从而产生光生载流子。因此吸收层400的禁带宽度小于或等于入射光子的能量。吸收层400相对于本征层500而言为窄带隙半导体层，而本征层500相对吸收层400而言为宽带隙半导体层。即吸收层400为窄带隙半导体材料层，而本征层500、场控层600、阻挡层700均为宽带隙半导体材料层。另外，本申请中的多子是指电子和空穴中的一种，少子则是指电子和空穴中的另一种。例如，对于N型掺杂的吸收层而言，其多子为电子，少子为空穴，而对于P型掺杂的吸收层而言，其多子为空穴，少子则为电子。
分别位于本征层500两侧的吸收层400和场控层600的掺杂类型不同，而阻挡层700的掺杂类型与场控层的掺杂类型相同，则阻挡层、场控层600、本征层500以及吸收层400构成了一个PIN结构，则由PIN结构的原理可知，该结构的耗尽层位于中间的本征层500中。由于本征层500的禁带宽度大于入射光子的能量，其相对于吸收层400而言为宽带隙材料，因此可以有效的减小红外探测器的产生-复合电流，即减小了探测器的暗电流。原因是，产生-复合机 制主要发生在耗尽层(空间电荷层)内，耗尽层内的产生-复合电流与本征载流子的浓度成正比，而本征载流子浓度与禁带宽度成反比，因此本申请中，通过势垒复合层与吸收层400形成的PIN结构，可以将耗尽层全部转移至宽带隙的本征层500中，从而可以减小产生-复合电流。且将与本征层500相邻的场控层设置为轻掺杂，其掺杂过程几乎不会对本征层有不利影响，同时其还用于消除本征层500与吸收层400界面处形成的少子势垒，阻止了少子在本征层500和吸收层400界面处的累积，有利于改善吸收层400中少子的运输。因此，场控层600可以改善本征层500中靠近阻挡层700一侧的耗尽层势垒宽度，减小隧道击穿概率。而阻挡层700由于相对场控层600远离本征层400，因此其可以相对于场控层600而言为重掺杂，可有效的抑制第一接触层800表面的漏电。
在本申请提供的红外探测器中，吸收层400的掺杂类型为N型掺杂，场控层600与阻挡层700的掺杂类型均为P型掺杂。则本申请提供的红外探测器为P-Bp-B2-N型红外探测器，其中，P-Bp-B2-N中的P是指P型掺杂的第一接触层800，P-Bp-B2-N中的Bp是指P型掺杂的阻挡层700，B2是指有场控层600、本征层500构成的双势垒层，则P-Bp-B2-N中的Bp-B2为本申请提供的势垒复合层，而P-Bp-B2-N中的N是指N掺杂类型的吸收层400。因此，在本实施例中吸收层400中的多子为电子，少子为空穴。由Bp-B2势垒复合层由于包括与吸收层400相邻的本征层以及包括与吸收层400掺杂类型相反的场控层600以及阻挡层700，则P-Bp-B2-N结构具有PIN结构的功能，即耗尽层完全位于本征层500中。同时由于Bp-B2势垒复合层为吸收层400中的电子势垒层，因此P-Bp-B2-N型红外探测器还具有PBN单极势垒结构(P型接触层与N型吸收层之间设置有电子势垒B层)的功能。
由上可见，本申请提供的红外探测器主要包括第一接触层、第二接触层以及位于所述第一接触层与第二接触之间的吸收层和势垒复合层。其中，势垒复合层包括依次相邻且均为宽带隙半导体材料的的本征层、场控层和阻挡层，本征层与窄带隙半导体材料的吸收层相邻。且吸收层的掺杂类型为N型掺杂，而场控层和阻挡层均为P型掺杂，从而可使势垒复合层与吸收层形成PIN结构，使得红外探测器的耗尽层转移到宽带隙的本征层中，有效的抑制了探测器中的产生-复合电流，红外探测器的暗电流。此外，由于场控层600可有效的避免吸收层400中的少子在本征层500中的累积，且同时可调控本征层500中的电荷分布，进一步提高了红外探测器的探测性能。
在一些实施例中，如图2所示，依据本申请提供的红外探测器，还包括衬底100、缓冲层200。其中，缓冲层200位于衬底100与第二接触层300之间，具体的，缓冲层200位于衬底100的一侧，如衬底100包括相对的第一侧和第二侧，缓冲层200的第二侧与衬底100的第一侧接触，缓冲层200背离衬底100第一侧的一侧为第二侧。第二接触层300位于缓冲层200背离衬底100的一侧，即缓冲层200的第二侧与第二接触层300接触。
第二接触层300的掺杂类型与吸收层400的掺杂类型相同，且其掺杂浓度大于吸收层400的掺杂浓度。因此，第二接触层300相对于吸收层400而言为重掺杂型半导体层，而吸收层400则为轻掺杂型半导体层。此外，在一些实施例中，衬底100的第二侧为入射光子的入射侧，即对应的红外探测器为背照式红外探测器，则为了避免入射光子在入射到吸收层400之前被其它各半导体层吸收，缓冲层200与第二接触层300的禁带宽度都要大于入射光子的能量，即缓冲层200与第二接触层300均为宽带隙半导体材料层，此外衬底100也为宽带隙半导体材料，其禁带宽度也大于入射光子的能量。
图4为本申请提供的P-Bp-B2-N型红外探测器中的第一接触层800、势垒复合层、吸收层以及第二接触层的能带次序示意图。图4中的纵坐标为价带顶EV和导带底EC的势能，横坐标为P-Bp-B2-N型红外探测器各功能层的厚度。
如图4所示，在一些实施例中，本征层500的导带底能量、场控层600的导带底能量、阻挡层700的导带底能量依次增加，即本征层500的导带底能量与吸收层400的导带底能量之差、场控层600的导带底能量与吸收层400的导带底能量之差、阻挡层700的导带底能量与吸收层400的导带底能量之差依次增加，可对势垒复合层的各功能层的功能分别优化。因此，在一些实施例中，阻挡层700的禁带宽度比场控层600的禁带宽度以及本征层500的禁带宽度均要高。本征层500、阻挡层600相比于吸收层400而言，均为宽带隙材料，即本征层500、阻挡层600的禁带宽度均需大于入射光子的能量。
此外，在本申请实施例中，如图4所示，吸收层400中的少子依次由经本征层500、场控层600、阻挡层700的价带顶运输至第一接触层800中。因为，场控层600可调控本征层500中的电场，使本征层500中的最低价带顶能量相对于吸收层400的价带底能量提升，从而可以消除吸收层400与本征层500的交界面区域的少子累积，从而使吸收层400中的少子顺利通过各层的价带顶运 输到第一接触层400中。
进一步的，在一些实施例中，第一接触层800为窄带隙半导体材料层，如第一接触层800的禁带宽度小于本征层500的禁带宽度，即第一接触层800相对于本征层500而言为窄带隙半导体材料层。
在一些实施例中，为了进一步优化本申请提供的红外探测器的性能，可以将阻挡层700的厚度设计为大于或等于本征层500的厚度，而将本征层500的厚度设计成大于或等于场控层600的厚度。但是需要说明的是，在其它实施例中，阻挡层700、场控层600、本征层500的厚度关系不限定，可以根据实际应用需求调整。
参考图4所示，场控层与本征层中的点划线虚线，为势垒复合层仅包括阻挡层与本征层而不包括场控层的结构对应的本征层的能带，显然，其相对于有场控层时的本征层的能带(实线)凹陷得的更多，这会造成吸收层中的少子都被累积在这个凹陷中，不利于少子载流子的运输，此外若不增加场控层，在反偏的情况下，本征层靠近阻挡层一侧也容易发生隧道击穿现象。在图4还示意了本申请提供的P-Bp-B2-N型红外探测器在加反向偏压时，本征层的能带结构，如图5中的另一非点划虚线所示。
如图3所示，在一些实施例中，本申请提供的红外探测器由衬底方向往第一接触层方向依次包括InP衬底100、宽带隙缓冲层200、N +型第二接触层300、N -型吸收层400、宽带隙的本征层500、P -型场控层600、P +型阻挡层700以及P +型第一接触层800。其中，在本申请中，N -相对于N +而言是轻掺杂，N +相对于N -而言是重掺杂，P -相对于P +而言是轻掺杂，P +相对于P -而言是重掺杂。
本申请提供的P-Bp-B2-N型红外探测器适用于InGaAs短波红外探测器或InGaAs/GaAsSb二类超晶格短波红外探测器，尤其适用于延伸波长的InGaAs短波红外探测器或InGaAs/GaAsSb二类超晶格短波红外探测器，即吸收层中的In的组分相对较高。
在一些实施例中，本征层500和场控层600均为宽带隙锑(Sb)化物半导体材料层，所述本征层中锑组分与所述吸收层的晶格匹配。
具体的，在一些实施例中，吸收层400为In xGa 1-xAs层，其中，0.47≤x≤0.82。吸收层400为N型Si(硅)或S(硫)轻掺杂的N -吸收层，掺杂的施主浓度为0.5-5E+17cm -3，N -型的In xGa 1-xAs吸收层的厚度为2.0-3.0μm。
在一些实施例中，吸收层400为In 0.53Ga 0.47As/GaAs ySb 1-y二类超晶格层，其中，In 0.53Ga 0.47As阱层厚度为4-7nm，GaAs ySb 1-y垒层厚度为4-7nm，组分y的范围为：0.47≤y≤0.51，周期数为150-300。
在一些实施例中，本征层500和场控层600均为禁带宽度大于预设值的含Sb化合物半导体层，即本征层为含Sb的宽带系半导体层。
具体的，本征层500为Al zGa 1-zAs ySb 1-y层，其中，Al组分z的范围为：0.2≤z≤0.5，本征层500的厚度为0.3-1.0μm，且其背景载流子浓度为1-10E+15cm -3。当吸收层为上述In xGa 1-xAs层时，调节本征层500中Sb组分为预设组分，使其与吸收层之间晶格匹配，即确保本征层与吸收层之间的晶格失配率低于所允许的最大失配率。
具体的，在一些实施例中，场控层600为轻掺杂的p -型Al zGa 1-zAs ySb 1-y层，其组分与N -型Al zGa 1-zAs ySb 1-y本征层相同，而其厚度为0.2-0.8μm，掺杂受主浓度为0.5-5E+17cm -3。在其它实施例中，场控层还可以为宽带隙的InP层。
在一些实施例中，阻挡层700为AlAsSb层、InAlAs层、InP层、InAsP层中的至少一种，具体的，在本实施例中，阻挡层700为P+型AlAs ySb 1-y层，其厚度0.5-2.0μm，掺杂受主浓度0.5-2E+18cm -3。
继续参考图5所示，具体的，在一些实施例中，第一接触层为P +型In xGa 1-xAs层或GaAs ySb 1-y层，组分y的范围为：0.47≤y≤0.51，其掺杂受主浓度≥2E+18cm -3，其厚度0.05-0.2μm。第二接触层300为N+型的宽带隙的InP层或InAlAs层，其为Si或S重掺杂，掺杂施主浓度为2-8E+18cm -3，其厚度为0.2-1.0μm。此外，衬底100为单晶的N型或半绝缘型InP衬底。缓冲层200为宽带隙半导体材料层，例如其可选自InAsP层、InP层、InAlAs层中的至少一种。
如图5所示，在一些实施例，依据本申请提供的的红外探测器还进一步包括钝化层9012、第一电极903、第二电极902。钝化层9012的一部分位于第一接触层800背离阻挡层700的一侧，且具有第一类开口(如图8e中的T4)和第二类开口(如图8d中的T3)。第一类开口裸露第一接触层800，第二类开口裸露依次穿过第一接触层800、势垒复合层、吸收层400并停止于第二接触层300的电极沟槽(如图8e中右侧的深沟槽)。第一电极904穿过第一类开口与第一接触层800形成欧姆接触；第二电极300穿过电极沟槽与第二接触层300 形成欧姆接触。其中，钝化层选自SiN x、Al 2O 3、SiO 2中的至少一种，而第一电极与第二电极均为Cr/Au或Ti/Pt/Au多层金属电极。
继续参考图5所示，在一些实施例中，第一接触层800以及所述势垒复合层被台面沟槽(如图8b中的T2)分隔为多个设置于吸收层400的台面，台面沟槽由第一接触层800的表面延伸至吸收层400的表面，且钝化层9012由第一接触层800背离阻挡层700的一侧延伸至台面沟槽侧壁及底部，从而将台面裸露在外的部分包裹，仅裸露第一电极和第二电极。
由上可见，本申请提供各实施例的红外探测器可存在以下有益效果：
1、采用宽带隙的Sb化合物作为势垒，并引入本征层、场控层的双Sb化合物作为势垒，可将耗尽区由窄带隙吸收层转移至宽带隙势垒区，使得吸收层由扩散机制主导，体内产生-复合暗电流大幅降低。
2、通过在势垒复合层中设置场控层，提升了结构调制的自由度，不仅能够改善载流子收集效率，而且能够有效控制作为耗尽区的本征层的隧道击穿暗电流。
3、宽带隙的势垒复合层的设计可有效抑制表面暗电流。
此外，本申请还提供了依据本申请一实施例提供的红外探测器的制备方法，其制备方法流程示意图如图6所示,在本实施例中，所述制备方法包括S1、S2、S3以及S4。
S1：在衬底上外延生长第二接触层。
S2：在所述第二接触上外延生长N型掺杂的窄带隙半导体材料，形成吸收层。
S3：在所述吸收层上依次外延生长本征层、场控层以及阻挡层，形成势垒复合层，所述本征层为宽带隙半导体材料层，所述场控层和所述阻挡层均为P型掺杂的宽带隙半导体材料层。
S4：在所述阻挡层上外延生长第一接触层。
图7为依据本申请提供的另一实施例提供的红外探测器的制备方法流程示意图，其各个步骤中形成的中间结构可参考图8a-8e所示。在本实施例中，与图6不同的是，在S1之前，所述制备方法还进一步包括S0：在所述衬底上外延生长缓冲层。则在本实施例中，S1具体为：在所述衬底上的缓冲层上外延生 长第二接触层。
具体的，采用MOCVD(Metal-organic Chemical Vapor Deposition，金属有机化合物化学气相沉淀)或MBE(Molecular beam epitaxy，分子束外延)技术，在N型或半绝缘型InP单晶衬底上依次外延生长各功能层，即在所述衬底上依次外延生长缓冲层、第二接触层、吸收层、势垒复合层以及第二接触层后形成的结构如图2所示。
此外，继续参考图7所示，在本实施例中，除了包括S0以及图6中的S1至S4之外，所述制备方法还进一步包括在S4之后执行的S5至S9，各步骤具体如下：
S5：依次刻蚀第一接触层和势垒复合层，以形成由台面沟槽隔离开的台面。
具体的，如图8a所示，先在第一接触层800的表面形成刻蚀掩模层9011，如利用光刻胶或SiO 2、SiN x介质膜制作具有开口T1的刻蚀掩膜层901，所述开口T1裸露台面沟槽所在区域。通过湿法或干法刻蚀方法依次将台面沟槽所在区域的第一接触层800以及势垒复合层(阻挡层700、场控层600、本征层500)刻蚀掉，且刻蚀停止于吸收层400的表面，从而形成如图8b所示的台面沟槽T2，S1中形成的第一接触层800和势垒复合层被台面沟槽T2隔离成多个位于吸收层400表面的台面。
S6：对台面执行表面钝化工艺，以形成包裹台面的钝化层。
如图8c所示，在形成台面的红外探测器中间结构表面沉积SiN x或Al 2O 3、SiO 2介质膜，以形成包裹台面的钝化层9012，且钝化层还覆盖在被台面沟槽T2裸露的吸收层400上，从而可保护红外探测器中间结构表面不被氧化等。
S7：刻蚀钝化层，以形成第二类开口，并由经第二类开口进行刻蚀，以形成电极沟槽。
如图8d所示，利用湿法或干法刻蚀工艺在S3中形成的钝化层9012上形成第二类开口T3，使第二类开口裸露需要制作第二电极902的区域，然后蚀刻该区域，依次刻蚀掉该区域对应的第一接触层800、势垒复合层、吸收层400，并使刻蚀停止于第二接触层300中，以形成电极沟槽。
S8：刻蚀钝化层，以形成第一类开口。
如图8e所示，利用光刻及湿法或干法刻蚀方式在钝化层9012上形成第一 类开口T4，以将需要制作第一电极903的区域裸露。
S9：分别形成与第一接触层形成欧姆接触的第一电极以及与第二接触层形成欧姆接触的第二电极。
采用Cr/Au或Ti/Pt/Au多层金属制作金-半欧姆接触的第一电极903以及第二电极902，从而形成如图5所示的红外探测器。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围之内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (12)

  1. 一种红外探测器，其特征在于，包括：第一接触层、第二接触层以及位于所述第一接触层和第二接触层之间的吸收层和势垒复合层；
    所述吸收层为N型掺杂的窄带隙半导体材料层；
    所述势垒复合层包括依次相邻的本征层、场控层以及阻挡层，所述本征层与所述吸收层相邻，且为宽带隙半导体材料层，所述场控层和所述阻挡层均为P型掺杂的宽带隙半导体材料层。
  2. 根据权利要求1所述的红外探测器，其特征在于，还包括衬底和缓冲层；
    所述衬底为N型掺杂InP衬底或半绝缘型InP衬底；
    所述缓冲层为宽带隙半导体材料层；
    所述缓冲层位于所述第二接触层和所述衬底之间，所述吸收层位于所述第二接触层背离所述缓冲层的一侧。
  3. 根据权利要求2所述的红外探测器，其特征在于，
    所述第一接触层与所述阻挡层相邻，且为P型掺杂的窄带隙半导体材料层；
    所述第二接触层与所述吸收层相邻，且为N型掺杂的宽带隙半导体材料层，且所述第二接触层的掺杂浓度大于所述吸收层的掺杂浓度。
  4. 根据权利要求3所述的红外探测器，其特征在于，所述本征层的导带底能量、所述场控层的导带底能量、所述阻挡层的导带底能量依次增加；
    所述阻挡层的禁带宽度大于所述场控层的禁带宽度，所述场控层的禁带宽度大于或等于所述本征层的禁带宽度。
  5. 根据权利要求1所述的红外探测器，其特征在于，所述吸收层为InGaAs层或为InGaAs/GaAsSb二类超晶格层。
  6. 根据权利要求5所述的红外探测器，其特征在于，所述本征层和所述场控层均为宽带隙锑化物半导体材料层，所述本征层中锑组分与所述吸收层的晶格匹配。
  7. 根据权利要求6所述的红外探测器，其特征在于，所述本征层为AlGaAsSb层；
    所述场控层为AlGaAsSb层或InP层；
    所述阻挡层为AlAsSb层、InAlAs层、InP层、InAsP层中的至少一种；
    所述第一接触层为InGaAs层或GaAsSb层；
    所述第二接触层为InP层或InAlAs层。
  8. 根据权利要求7所述的红外探测器，其特征在于，所述第一接触层为In xGa 1-xAs层或GaAs ySb 1-y层，所述第一接触层掺杂的受主浓度大于或等于2E+18cm -3，所述第一接触层的厚度为0.05-0.2μm；
    所述吸收层为硅或硫掺杂的In xGa 1-xAs层，所述In xGa 1-xAs层的厚度为2.0-3.0μm，或者所述吸收层为In 0.53Ga 0.47As/GaAs ySb 1-y二类超晶格层，其中，所述In 0.53Ga 0.47As/GaAs ySb 1-y二类超晶格层的In 0.53Ga 0.47As阱层的厚度为4-7nm，GaAs ySb 1-y势垒层的厚度为4-7nm，所述In 0.53Ga 0.47As/GaAs ySb 1-y二类超晶格层的周期数为150-300；
    所述本征层与所述场控层均为Al zGa 1-zAs ySb 1-y层，所述本征层的厚度为0.3-1.0μm，且所述本征层的背景载流子浓度为1-10E+15cm -3，所述场控层的厚度为0.2-0.8μm，所述场控层掺杂的受主浓度为0.5-5E+17cm -3；
    所述阻挡层为AlAs ySb 1-y层，所述阻挡层掺杂的受主浓度为0.5-2E+18cm -3，所述阻挡层的厚度为0.5-2.0μm；
    所述第二接触层为硅或硫掺杂的InP层或InAlAs层，所述第二 接触层掺杂的施主浓度为2-8E+18cm -3，所述第二接触层的厚度为0.2-1.0μm；
    其中，所述x，y，z的范围分别为：0.47≤x≤0.82，0.47≤y≤0.51，0.2≤z≤0.5。
  9. 根据权利要求1至8中任一项所述的红外探测器，其特征在于，还包括钝化层、第一电极、第二电极；
    所述钝化层的至少部分位于所述第一接触层背离所述阻挡层的一侧，且具有第一类开口和第二类开口；
    所述第一类开口裸露所述第一接触层，所述第二类开口裸露依次穿过所述第一接触层、所述势垒复合层、所述吸收层并停止于所述第二接触层的电极沟槽；
    所述第一电极穿过所述第一类开口与所述第一接触层形成欧姆接触；
    所述第二电极穿过所述电极沟槽与所述第二接触层形成欧姆接触。
  10. 根据权利要求9所述的红外探测器，其特征在于，所述第一接触层以及所述势垒复合层被台面沟槽分隔为多个设置于所述吸收层的台面，所述台面沟槽由所述第一接触层的表面延伸至所述吸收层的表面；
    所述钝化层由所述第一接触层背离所述阻挡层的一侧延伸至所述台面沟槽侧壁及底部。
  11. 一种如权利要求1中所述的红外探测器的制备方法，其特征在于，包括:
    在衬底上外延生长第二接触层；
    在所述第二接触上外延生长N型掺杂的窄带隙半导体材料，形成吸收层；
    在所述吸收层上依次外延生长本征层、场控层以及阻挡层，形成 势垒复合层，所述本征层为宽带隙半导体材料层，所述场控层和所述阻挡层均为P型掺杂的宽带隙半导体材料层；
    在所述阻挡层上外延生长第一接触层。
  12. 根据权利要求11所述制备方法，其特征在于，在所述在所述衬底上外延生长第二接触层之前，所述制备方法还包括：
    在所述衬底上外延生长缓冲层；
    所述在衬底上外延生长第二接触层，包括：
    在所述衬底上的缓冲层上外延生长第二接触层；
    在所述在所述阻挡层上外延生长第一接触层之后，所述制备方法还包括：
    刻蚀所述第一接触层和所述势垒复合层，以形成由台面沟槽隔离开的台面；
    对所述台面执行表面钝化工艺，以形成包裹所述台面的钝化层；
    刻蚀所述钝化层，以形成所述第二类开口，并由经所述第二类开口进行刻蚀，以形成所述电极沟槽；
    刻蚀所述钝化层，以形成所述第一类开口；
    分别形成与所述第一接触层形成欧姆接触的第一电极以及与所述第二接触层形成欧姆接触的第二电极。
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