InP-based ultra-wide spectrum photodetector and preparation method thereof

Abstract

The present invention provides an InP-based ultra-wide spectrum photodetector and a preparation method thereof. The present invention uses AlAsSb and InAlAs or InP as an electron blocking layer and a transition layer to extend the test wavelength of the photodetector to the visible light and ultraviolet bands, and uses InGaAs bulk material and InGaAs / GaAsSb two-type superlattice material as an absorption layer of the semiconductor photodetector to extend the test wavelength of the photodetector to the near infrared and extended short-wave infrared bands. When the difference between the formed electron ground state energy level and the hole ground state energy level is less than the energy corresponding to the photon extending the short-wave infrared wavelength, the light extending the short-wave infrared wavelength can be absorbed, thereby achieving coverage of the extended short-wave infrared band. The photodetector uses the InGaAs / GaAsSb two-type superlattice lattice matched to the InP substrate as the absorption region, and has the advantages of lower dark current and monolithic integration compared to the high indium component lattice mismatched InGaAs extended short-wave infrared detector.

Description

Technical Field

[0001] The invention relates to an ultra-wide spectrum semiconductor photoelectric detector with an InP-based spectral response from ultraviolet to extended short-wave infrared band (250nm-2500nm) and a preparation method of the ultra-wide spectrum semiconductor photoelectric detector, belonging to the technical field of photoelectric detectors. Background Art

[0002] With the development of gas inspection, atmospheric sensing and other related fields, full-spectrum detection from ultraviolet to infrared will help to realize the inspection of multiple gases. At present, full-spectrum detection is usually achieved by switching between multiple detectors with different band responses, which makes the test system relatively complex. The realization of high-performance ultra-wide spectrum photodetectors will greatly simplify the light detection system. Currently reported wide-spectrum detectors often have disadvantages such as poor performance and high dark current, and the detection range is rarely extended from the ultraviolet band to the extended short-wave infrared band. Summary of the invention

[0003] The purpose of the present invention is to provide a detector with wider spectral response, lower dark current, response spectrum from ultraviolet to extended short-wave near-infrared, and room temperature operation, so as to solve the system complexity problem caused by switching detectors of different bands in the existing full-spectrum system.

[0004] In order to achieve the above object, a technical solution of the present invention is to provide an InP-based ultra-wide spectrum photoelectric detector, the spectral response of the InP-based ultra-wide spectrum photoelectric detector is from ultraviolet to extended short-wave infrared band, characterized in that the InP-based ultra-wide spectrum photoelectric detector at least comprises:

[0005] An InP substrate layer, a cathode contact layer, a plurality of periodically repeated InGaAs / GaAsSb superlattice absorption layers, an InGaAs absorption layer, an InAlAs or InP transition layer, an electron blocking layer and an anode contact layer are stacked in sequence, wherein: the InGaAs / GaAsSb superlattice absorption layer and the InGaAs absorption layer are used to absorb photons to excite electron-hole pairs therein; the electron blocking layer is used to block electrons from diffusing toward the anode; the InAlAs or InP transition layer is used to perform valence band transition between the electron blocking layer and the InGaAs absorption layer;

[0006] A cathode is formed on the cathode contact layer, and an ohmic contact is formed between the cathode and the cathode contact layer;

[0007] The anode is formed on the anode contact layer, and an ohmic contact is formed between the anode and the anode contact layer;

[0008] In the anode contact layer, a groove window is formed by removing part of the material to further enhance the response in the ultraviolet and visible bands.

[0009] Preferably, in each period of the InGaAs / GaAsSb superlattice absorption layer, the thickness of the InGaAs layer is 3-6nm, and the thickness of the GaAsSb layer is 3-6nm; the total thickness of the InGaAs / GaAsSb superlattice absorption layer is 1000-5000nm, which is selected according to the relevant performance requirements of the device, and the doping concentration is i-type intrinsic doping.

[0010] Preferably, the thickness of the InGaAs absorption layer is 200-1000 nm, and the doping concentration is i-type intrinsic doping.

[0011] Preferably, the thickness of the cathode contact layer is 500 nm; the thickness of the electron blocking layer is 20 nm; the thickness of the InAlAs or InP transition layer is 20 nm; and the thickness of the anode contact layer is 10 nm.

[0012] Preferably, the cathode contact layer is made of N-type heavily doped semiconductor material with a doping concentration of 1×10 18 cm -3 The anode contact layer is made of P-type heavily doped semiconductor material with a doping concentration of 1×10 18 cm -3 The electron blocking layer is made of P-type heavily doped wide bandgap semiconductor material with a doping concentration of 1×10 18 cm -3 The transition layer is made of P-type doped wide bandgap semiconductor material with a doping concentration of 0.5-3×10 17 cm -3 ;

[0013] All semiconductor materials used in the cathode contact layer, the anode contact layer, the electron blocking layer and the transition layer are lattice matched to the InP substrate layer.

[0014] Preferably, the semiconductor material used in the cathode contact layer is InGaAs; the semiconductor material used in the anode contact layer is InGaAs; the semiconductor material used in the electron blocking layer is AlAsSb; and the semiconductor material used in the transition layer is InAlAs.

[0015] Another technical solution of the present invention is to provide a method for preparing the aforementioned InP-based ultra-wide spectrum photoelectric detector, characterized in that it comprises at least the following steps:

[0016] A cathode contact layer, an InGaAs / GaAsSb superlattice absorption layer, an InGaAs absorption layer, an InAlAs or InP transition layer, an electron blocking layer and an anode contact layer are sequentially grown on an InP substrate layer by a molecular beam epitaxy method or an organic metal chemical vapor deposition method;

[0017] Titanium, platinum and gold are deposited on the upper surface of the anode contact layer by electron beam evaporation technology to form an anode;

[0018] Etching sequentially from the anode downwards by dry or wet etching, with the etching surface stopping within the cathode contact layer to form a columnar step protruding from the cathode contact layer;

[0019] Titanium, platinum and gold are sequentially deposited on the surface of the cathode contact layer by electron beam evaporation technology to form a cathode;

[0020] In the anode contact layer, wet etching or dry etching is used to make groove windows to remove part of the material, thereby further enhancing the response in the ultraviolet and visible bands.

[0021] Preferably, the method further comprises the step of passivating the sidewalls of the columnar steps.

[0022] Preferably, a passivation layer is formed by passivating the sidewalls of the columnar steps, and the material of the passivation layer includes silicon nitride or silicon dioxide.

[0023] Preferably, the thicknesses of titanium, platinum and gold of the anode are 20 nm, 20 nm and 80 nm respectively; the thicknesses of titanium, platinum and gold of the cathode are 20 nm, 20 nm and 80 nm respectively.

[0024] The present invention uses a type II superlattice structure of InGaAs / GaAsSb based on an InP substrate to realize a detector from ultraviolet to extended short-wave near-infrared. The response band of the photodetector at room temperature is 250 nanometers to 2.5 micrometers. Compared with other detectors reported so far, the photodetector disclosed in the present invention has a larger spectral response range and has great application potential in related fields such as full spectrum inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figures 1 to 5 The structure schematic diagram of each step of the method for preparing the ultra-wide spectrum semiconductor photodetector with spectral response from ultraviolet to extended short-wave infrared band of the present invention is shown, wherein Figure 5 Also shown is a schematic structural diagram of the ultra-wide spectrum semiconductor photodetector of the present invention.

[0026] In the figure: 10-substrate layer; 11-cathode contact layer; 12-InGaAs / GaAsSb superlattice absorption layer; 13-InGaAs absorption layer; 14-electron blocking layer; 15-transition layer; 16-anode contact layer; 17-anode; 18-columnar step; 19-cathode; 20-insulating layer; 21-coplanar waveguide electrode; 22-incident light; 23-groove window. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] See also Figures 1 to 5 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0029] Embodiment 1

[0030] like Figure 4 and Figure 5 As shown, this embodiment provides an ultra-wide spectrum semiconductor photodetector for spectral response from ultraviolet to extended short-wave infrared band, and the photodetector at least includes:

[0031] A substrate layer 10, a cathode contact layer 11, an InGaAs / GaAsSb superlattice absorption layer 12, an InGaAs absorption layer 13, an electron blocking layer 14, a transition layer 15 and an anode contact layer 16 are stacked in sequence, wherein: the InGaAs / GaAsSb superlattice absorption layer 12 and the InGaAs absorption layer 13 are used to absorb photons to excite electron-hole pairs therein; the electron blocking layer 14 is used to block electrons from diffusing toward the anode 17; the transition layer 15 is used to provide a valence band transition between the electron blocking layer 14 and the InGaAs absorption layer 13;

[0032] A cathode 19 is formed on the cathode contact layer 11, and an ohmic contact is formed between the cathode 19 and the cathode contact layer 11;

[0033] The anode 17 is formed on the anode contact layer 16 , and an ohmic contact is formed between the anode 17 and the anode contact layer 16 .

[0034] The semiconductor photodetector of this embodiment uses AlAsSb and InAlAs or InP as the electron blocking layer 14 and the transition layer 15 to extend the test wavelength of the photodetector to the visible light and ultraviolet bands. The InGaAs / GaAsSb superlattice material system and InGaAs material are used as the InGaAs / GaAsSb superlattice absorption layer 12 and the InGaAs absorption layer 13 of the semiconductor photodetector, and the test wavelength of the photodetector can be extended to the extended short-wave infrared band. When the difference between the formed electron ground state energy level and the hole ground state energy level is less than the energy corresponding to the photon extending the short-wave infrared wavelength, the InGaAs / GaAsSb superlattice absorption layer 12 and the InGaAs absorption layer 13 can absorb the light extending the short-wave infrared wavelength, thereby achieving coverage of the extended short-wave infrared band. The photodetector uses the InGaAs / GaAsSb type II superlattice lattice matched to the InP substrate as the absorption region, and has the advantages of lower dark current and monolithic integration compared to the high indium component lattice mismatched InGaAs extended short-wave infrared detector.

[0035] As an example, the InGaAs / GaAsSb superlattice absorption layer 12 includes a plurality of periodically repeated InGaAs / GaAsSb superlattice absorption layers, wherein the thickness of the InGaAs layer in each period is about 5 nm, and the thickness of the GaAsSb layer is about 5 nm. The total thickness of the InGaAs / GaAsSb superlattice absorption layer 12 is between 1000 nm and 5000 nm; and the doping is type I intrinsic doping.

[0036] As an example, the substrate layer 10 includes an InP substrate layer, the cathode contact layer 11 uses an N-type heavily doped semiconductor material, the anode contact layer 16 uses a P-type heavily doped semiconductor material, the electron blocking layer 15 uses a P-type heavily doped wide bandgap semiconductor material, and the transition layer 14 uses a P-type doped wide bandgap semiconductor material. All semiconductor materials used in the cathode contact layer 11, the anode contact layer 16, the electron blocking layer 15, and the transition layer 14 are lattice-matched to the InP substrate layer, which can effectively reduce problems such as high dark current caused by defects and dislocations, and improve the detection sensitivity of the detector. Preferably, the doping concentration of the cathode contact layer 11 is 1×10 18 cm -3 The doping concentration of the anode contact layer 16 is 1×10 18 cm -3 The doping concentration of the electron blocking layer 15 is 1×10 18 cm -3 The doping concentration of the transition layer 14 is 1×10 17 cm -3 about.

[0037] Preferably, the semiconductor material used in the cathode contact layer 11 is InGaAs, the semiconductor material used in the anode contact layer 16 is InGaAs, the semiconductor material used in the electron blocking layer 15 is AlAsSb, and the semiconductor material used in the transition layer 14 is InAlAs.

[0038] Preferably, the thickness of the cathode contact layer 11 is about 500 nm, the thickness of the electron blocking layer 15 is about 20 nm, the thickness of the transition layer 14 is about 20 nm, and the thickness of the anode contact layer 16 is about 10 nm.

[0039] Embodiment 2

[0040] like Figures 1 to 5 As shown, this embodiment provides a method for preparing an ultra-wide spectrum semiconductor photodetector with a spectral response from ultraviolet to an extended short-wave infrared band. The ultra-wide spectrum semiconductor photodetector described in Example 1 can be prepared by this preparation method. The beneficial effects that can be achieved by the prepared photodetector can be referred to Example 1 and will not be described in detail here.

[0041] The preparation method comprises:

[0042] like Figure 1 As shown, step S1: growing a cathode contact layer 11, an InGaAs / GaAsSb superlattice absorption layer 12, an InGaAs absorption layer 13, an electron blocking layer 14, a transition layer 15 and an anode contact layer 16 on a substrate layer 10 by using a molecular beam epitaxy method.

[0043] In this embodiment, the parameters such as materials, thickness and doping concentration of the above-mentioned layers are shown in Table 1:

[0044] Table 1

[0045]

[0046] like Figure 2 As shown, step S2: using electron beam evaporation technology to evaporate titanium, platinum and gold on the upper surface of the anode contact layer 16 to form the anode 17. In this embodiment, the thicknesses of titanium, platinum and gold of the anode 17 are selected to be 20nm, 20nm and 80nm respectively.

[0047] like Figure 3 As shown, step S3: using wet etching to sequentially etch downward from the anode 17, the etching surface stops in the cathode contact layer 11, so as to form a columnar step 18 protruding from the cathode contact layer 11. Using wet etching to etch downward from the anode 17, the etching surface stops at the upper surface of the electron blocking layer 15, so as to form a groove window 23 recessed in the anode contact layer 16.

[0048] As an example, after the columnar step 18 is formed, the sidewall of the columnar step 18 needs to be passivated, and the insulating material used for the passivation is Si3N4.

[0049] like Figure 4 As shown, step S4: using electron beam evaporation technology to sequentially deposit titanium, platinum and gold on the surface of the cathode contact layer 11 to form a cathode 19. In this embodiment, the thicknesses of titanium, platinum and gold of the cathode 19 are selected to be 20nm, 20nm and 80nm respectively.

[0050] Experiments show that the spectral response (incident light 22) of the photodetector prepared by the above steps at room temperature ranges from 250nm to 2400nm, the responsivity reaches 0.13A / W at 2000nm, and the quantum efficiency reaches 61% at 630nm and 1310nm.

[0051] In summary, the present invention provides a wide-spectrum semiconductor photodetector for extending the short-wave infrared band and a preparation method thereof. The use of AlAsSb and InAlAs as electron blocking layers and transition layers can extend the test wavelength of the photodetector to the visible light and ultraviolet bands. The use of InGaAs / GaAsSb superlattice material system and InGaAs material as the absorption layer of the semiconductor photodetector can extend the test wavelength of the photodetector to the extended short-wave infrared band. When the difference between the formed electron ground state energy level and the hole ground state energy level is less than the energy corresponding to the photon extending the short-wave infrared wavelength, the light extending the short-wave infrared wavelength can be absorbed, thereby achieving coverage of the extended short-wave infrared band. The photodetector uses the second type of InGaAs / GaAsSb superlattice as the absorption region, and its longer carrier lifetime helps to improve the light response of the device. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An InP-based ultra-wide spectrum photodetector, the spectral response of which is from ultraviolet to extended short-wave infrared band, characterized in that: The InP-based ultra-wide spectrum photodetector comprises at least: An InP substrate layer, a cathode contact layer, a plurality of periodically repeated InGaAs / GaAsSb superlattice absorption layers, an InGaAs absorption layer, an InAlAs transition layer, an electron blocking layer and an anode contact layer are stacked in sequence, wherein: the InGaAs / GaAsSb superlattice absorption layer and the InGaAs absorption layer are used to absorb photons to excite electron-hole pairs therein; the electron blocking layer is used to block electrons from diffusing toward the anode; the InP or InAlAs transition layer is used to perform valence band transition between the electron blocking layer and the InGaAs absorption layer; the semiconductor material used in the electron blocking layer is AlAsSb; using AlAsSb and InAlAs as the electron blocking layer and transition layer can extend the test wavelength of the photodetector to the visible light and ultraviolet bands; the thickness of the electron blocking layer is 20nm; the thickness of the InAlAs or InP transition layer is 20nm; A cathode is formed on the cathode contact layer, and an ohmic contact is formed between the cathode and the cathode contact layer; The anode is formed on the anode contact layer, and an ohmic contact is formed between the anode and the anode contact layer; In the anode contact layer, a groove window is formed by removing part of the material to further enhance the response in the ultraviolet and visible bands.

2. An InP-based ultra-wide spectrum photodetector as claimed in claim 1, characterized in that: In each period of the InGaAs / GaAsSb superlattice absorption layer, the thickness of the InGaAs layer is 3-6nm, and the thickness of the GaAsSb layer is 3-6nm; the total thickness of the InGaAs / GaAsSb superlattice absorption layer is 1000-5000nm, which is selected according to the relevant performance requirements of the device, and the doping concentration is i-type intrinsic doping.

3. An InP-based ultra-wide spectrum photodetector as claimed in claim 1, characterized in that: The thickness of the InGaAs absorption layer is 200-1000 nm, and the doping concentration is i-type intrinsic doping.

4. The InP-based ultra-wide spectrum photodetector according to claim 1, characterized in that: The thickness of the cathode contact layer is 500 nm; the thickness of the electron blocking layer is 20 nm; the thickness of the InAlAs or InP transition layer is 20 nm; and the thickness of the anode contact layer is 10 nm.

5. The InP-based ultra-wide spectrum photodetector according to claim 1, characterized in that: The cathode contact layer is made of N-type heavily doped semiconductor material with a doping concentration of 1×10 18 cm -3 The anode contact layer is made of P-type heavily doped semiconductor material with a doping concentration of 1×10 18 cm -3 The electron blocking layer is made of P-type heavily doped wide bandgap semiconductor material with a doping concentration of 1×10 18 cm -3 The transition layer is made of P-type doped wide bandgap semiconductor material with a doping concentration of 0.5-3×10 17 cm -3 ; All semiconductor materials used in the cathode contact layer, the anode contact layer, the electron blocking layer and the transition layer are lattice matched to the InP substrate layer.

6. An InP-based ultra-wide spectrum photodetector as claimed in claim 5, characterized in that: The semiconductor material used in the cathode contact layer is InGaAs; the semiconductor material used in the anode contact layer is InGaAs.

7. A method for preparing an InP-based ultra-wide spectrum photodetector according to any one of claims 1 to 5, characterized in that: At least the following steps are included: A cathode contact layer, an InGaAs / GaAsSb superlattice absorption layer, an InGaAs absorption layer, an InAlAs or InP transition layer, an electron blocking layer and an anode contact layer are sequentially grown on an InP substrate layer by a molecular beam epitaxy method or an organic metal chemical vapor deposition method; Titanium, platinum and gold are deposited on the upper surface of the anode contact layer by electron beam evaporation technology to form an anode; Etching sequentially from the anode downwards by dry or wet etching, with the etching surface stopping within the cathode contact layer to form a columnar step protruding from the cathode contact layer; Titanium, platinum and gold are sequentially deposited on the surface of the cathode contact layer by electron beam evaporation technology to form a cathode; In the anode contact layer, wet etching or dry etching is used to make groove windows to remove part of the material, thereby further enhancing the response in the ultraviolet and visible bands.

8. The method for preparing an InP-based ultra-wide spectrum photodetector according to claim 7, characterized in that: The method also includes the step of passivating the sidewalls of the columnar steps.

9. The method for preparing an InP-based ultra-wide spectrum photodetector according to claim 8, characterized in that: A passivation layer is formed by passivating the sidewalls of the columnar steps, and the material of the passivation layer includes silicon nitride or silicon dioxide.

10. The method for preparing an InP-based ultra-wide spectrum photodetector according to claim 7, characterized in that: The thicknesses of titanium, platinum and gold of the anode are 20nm, 20nm and 80nm respectively; the thicknesses of titanium, platinum and gold of the cathode are 20nm, 20nm and 80nm respectively.

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