Short-wave dual-band infrared detector based on indium phosphide substrate and preparation method of short-wave dual-band infrared detector

Abstract

The invention relates to the technical field of infrared photoelectric materials and devices, in particular to a short-wave dual-band infrared detector based on an indium phosphide substrate and a preparation method of the short-wave dual-band infrared detector based on the indium phosphide substrate. An indium phosphide absorption layer, a first P-type contact layer, a second P-type contact layer, a short-wave infrared superlattice absorption layer and an N-type contact layer are sequentially grown on an N-type doped indium phosphide substrate. The metal lower electrode is in contact with the N-type doped indium phosphide substrate, the metal upper electrode is in contact with the N-type contact layer, and a light through hole is formed in the center of the metal upper electrode. The band gap characteristic of the N-type doped indium phosphide substrate is utilized to participate in spectral absorption and convert the spectral absorption into electric signals for detection, meanwhile, a back-to-back diode structure is adopted, different responses to short-wave dual-band infrared rays can be achieved by adjusting bias voltage, and due to the fact that the N-type doped indium phosphide substrate participates in light absorption, the sensitivity of short-wave dual-band infrared rays is improved. Therefore, the substrate does not need to be removed like a traditional method, the epitaxial structure is simple, the manufacturing cost is reduced, and the technological process is simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared photoelectric materials and devices, and in particular to a short-wave dual-band infrared detector based on an indium phosphide substrate and a preparation method thereof. Background Art

[0002] Infrared detection is a passive detection technology and has extremely important applications in many fields. For single-band infrared detectors, the contrast of the image depends on the difference in radiation intensity between the target and the background. However, the peak values ​​of infrared radiation intensity from different radiation sources are in different band ranges. The use of short-wave dual-band infrared detectors can simultaneously collect the spectrum of the target in different bands, enhance the contrast between the target and the normal temperature background, and improve the clarity of the image.

[0003] The structure of the shortwave dual-band infrared detector mainly includes a substrate and an epitaxial structure deposited on the substrate. In the structural design of the existing shortwave dual-band infrared detector, the substrate only serves as the basis of the epitaxial material to reduce the defects caused by the epitaxial growth material. The existence of the substrate will reduce the light response, resulting in a single light response band of the infrared detector. Therefore, it is necessary to set an doped buffer layer on the substrate to increase the barrier height difference to reduce the crosstalk between channels and reduce the dark current to improve the detection performance. Moreover, after the infrared detector structure is prepared, it is usually necessary to remove the substrate as much as possible to reduce the influence of the substrate on the light absorption efficiency, which will inevitably cause waste of the substrate layer and increase the production cost. Summary of the invention

[0004] The present invention provides a short-wave dual-band infrared detector based on an indium phosphide substrate and a preparation method thereof, so as to solve the defects of a traditional short-wave dual-band infrared detector, such as a single light response band, substrate influence on reducing light response and high manufacturing cost.

[0005] The present invention provides a short-wave dual-band infrared detector based on an indium phosphide substrate, comprising an N-type doped indium phosphide substrate and an epitaxial structure deposited on the N-type doped indium phosphide substrate, wherein the epitaxial structure is etched into a cylindrical shape and forms a step structure with the N-type doped indium phosphide substrate, wherein the step structure is provided with an annular metal lower electrode at a position corresponding to the N-type doped indium phosphide substrate, and the step structure is provided with an annular metal upper electrode at a position corresponding to the top of the epitaxial structure, and a light-through hole is formed at the center of the metal upper electrode, and the step structure is provided with a sulfide layer and a passivation layer in sequence in all other areas except for the metal lower electrode, the metal upper electrode and the areas corresponding to the light-through hole.

[0006] The epitaxial structure includes an indium phosphide absorption layer, a first P-type contact layer, a second P-type contact layer, a short-wave infrared superlattice absorption layer and an N-type contact layer, wherein the indium phosphide absorption layer is grown on the indium phosphide substrate; the first P-type contact layer is grown on the indium phosphide absorption layer, and the first P-type contact layer is doped with indium phosphide; the second P-type contact layer is grown on the first P-type contact layer, and the second P-type contact layer is doped with aluminum gallium arsenic antimony alloy; the short-wave infrared superlattice absorption layer is grown on the second P-type contact layer; the N-type contact layer is grown on the short-wave infrared superlattice absorption layer, and the N-type contact layer is doped with indium gallium arsenide.

[0007] According to the present invention, a short-wave dual-band infrared detector based on an indium phosphide substrate is provided, wherein the N-type doped indium phosphide substrate uses a (100) crystal orientation sulfur-doped N-type indium phosphide substrate.

[0008] According to a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the metal lower electrode and the metal upper electrode both include a titanium layer, a platinum layer and a gold layer from bottom to top, the titanium layer has a thickness of 20nm~80nm, the platinum layer has a thickness of 20nm~80nm, and the gold layer has a thickness of 250nm~400nm; the titanium layer of the metal lower electrode contacts the N-type doped indium phosphide substrate, and the titanium layer of the metal upper electrode contacts the N-type contact layer.

[0009] According to a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the indium phosphide absorption layer has a thickness of 500nm-2500nm and a band gap width of 1.34-1.35eV.

[0010] According to a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the short-wave infrared superlattice absorption layer is a gallium arsenide indium superlattice and / or a gallium arsenide antimony superlattice, the short-wave infrared superlattice absorption layer has a thickness of 500nm~2500nm, and a band gap width of 1.34~1.35eV.

[0011] According to a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the short-wave infrared superlattice absorption layer includes a plurality of indium gallium arsenide superlattice layers and a plurality of antimony gallium arsenide superlattice layers, and the plurality of indium gallium arsenide superlattice layers and the plurality of antimony gallium arsenide superlattice layers are cross-stacked and grown to form the short-wave infrared superlattice absorption layer.

[0012] The present invention also provides a method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate, which is suitable for preparing any of the above-mentioned short-wave dual-band infrared detectors based on an indium phosphide substrate, comprising: Using an N-type doped indium phosphide substrate as a structural substrate of an infrared detector, and performing degassing and deoxidation pretreatment on the N-type doped indium phosphide substrate; Based on the pre-treated N-type doped indium phosphide substrate, homoepitaxially growing an indium phosphide absorption layer on the N-type doped indium phosphide substrate; Growing a first P-type contact layer on the indium phosphide absorption layer; growing a second P-type contact layer on the first P-type contact layer; Growing a short-wave infrared superlattice absorption layer on the second P-type contact layer; Growing an N-type contact layer on the short-wave infrared superlattice absorption layer; Based on the epitaxial structure deposited on the N-type doped indium phosphide substrate composed of the indium phosphide absorption layer, the first P-type contact layer, the second P-type contact layer, the short-wave infrared superlattice absorption layer and the N-type contact layer, the side of the epitaxial structure is etched by inductively coupled plasma ICP to make the epitaxial structure cylindrical; Covering the N-type doped indium phosphide substrate and the epitaxial structure with a sulfide layer and a passivation layer; Using photolithography to prepare a mask at a portion of the passivation layer corresponding to the N-type doped indium phosphide substrate, forming a first annular opening by reactive ion etching, and using photolithography to prepare a mask at a portion of the passivation layer corresponding to the N-type contact layer, forming a second annular opening by reactive ion etching; The first annular opening is subjected to an evaporation electrode process to form an annular metal lower electrode; the second annular opening is subjected to an evaporation electrode process to form an annular metal upper electrode and a light-through hole.

[0013] According to a method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the pretreatment of degassing and deoxidizing the N-type doped indium phosphide substrate comprises: The N-type doped indium phosphide substrate is placed in a molecular beam epitaxy system injection chamber, maintained at a temperature of 200° C., and subjected to low-temperature degassing for 150 minutes; The N-type doped indium phosphide substrate that has completed low-temperature degassing is transferred into a buffer chamber of a molecular beam epitaxy system, maintained at a temperature of 360° C., and subjected to high-temperature degassing for 60 min to 100 min; The N-type doped indium phosphide substrate that has completed high-temperature degassing is transferred into a growth chamber of a molecular beam epitaxy system, the N-type doped indium phosphide substrate is gradually heated to 500° C. to 700° C., and a deoxidation treatment is performed for 15 min to 30 min to remove oxides on the surface of the N-type doped indium phosphide substrate.

[0014] According to a method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the growth rate of the indium phosphide absorption layer is 0.5 ML / s, and the thickness of the grown indium phosphide absorption layer is 500 nm to 2500 nm; The growth rate of the first P-type contact layer is 0.5 ML / s, and the thickness of the grown first P-type contact layer is 200 nm to 400 nm; The growth rate of the second P-type contact layer is 0.5 ML / s, and the thickness of the grown second P-type contact layer is 400 nm to 600 nm; The growth rate of the short-wave infrared superlattice absorption layer is 0.5 ML / s, and the thickness of the grown short-wave infrared superlattice absorption layer is 500nm-2500nm; The growth rate of the N-type contact layer is 0.5 ML / s, and the thickness of the grown N-type contact layer is 7000 nm to 150 nm.

[0015] According to a method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention, the step of subsequently growing a short-wave infrared superlattice absorption layer on the second P-type contact layer comprises: growing a GaAs indium superlattice layer on the second P-type contact layer, and growing a GaAs antimony superlattice layer on the grown GaAs indium superlattice layer; Taking the grown GaAsI superlattice layer and the GaAsSb superlattice layer as a periodic unit, multiple periodic units are repeatedly grown upward until the total thickness of all periodic units reaches 500nm~2500nm, thereby forming the short-wave infrared superlattice absorption layer.

[0016] The short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention and the preparation method thereof, take an N-type doped indium phosphide substrate 1 as the basis of the device, and can use a (100) crystal orientation sulfur (S) doped N-type InP substrate, the indium phosphide absorption layer is directly grown on the N-type doped indium phosphide substrate, the first P-type contact layer is grown on the indium phosphide absorption layer and doped with indium phosphide; the second P-type contact layer is grown on the first P-type contact layer and doped with aluminum gallium arsenic antimony alloy (AlGaAsSb); the short-wave infrared superlattice absorption layer is grown on the second P-type contact layer, and is formed by alternately stacking multiple periods of InGaAs and / or GaAsSb; the N-type contact layer is grown on the short-wave infrared superlattice absorption layer and doped with InGaAs. The metal lower electrode and the metal upper electrode are both ring-shaped, and the metal lower electrode is located at a position on the N-type doped indium phosphide substrate corresponding to the step structure, and contacts the substrate. The metal upper electrode is located at a position on the step structure corresponding to the top of the epitaxial structure, contacts the N-type contact layer, and has a light hole in its center for allowing light to enter the detector. The areas outside the metal lower electrode, the metal upper electrode and the light-through hole are covered with a sulfide layer and a passivation layer to protect the epitaxial structure and reduce unnecessary surface states. The present invention utilizes the band gap characteristics of the N-type doped indium phosphide substrate itself to participate in spectral absorption, converts it into an electrical signal for detection, and adopts a back-to-back diode structure. Different responses to short-wave dual-band infrared can be achieved by adjusting the bias voltage. Since the N-type doped indium phosphide substrate participates in light absorption, it is not necessary to remove the substrate as in the traditional method, thereby reducing the production cost and simplifying the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 The diagram is a schematic cross-sectional structure diagram of a short-wave dual-band infrared detector based on an indium phosphide substrate provided by the present invention.

[0019] Figure 2 The present invention is a schematic flow chart of a method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate.

[0020] Figure 3 It is a spectral response diagram of the short-wave dual-band infrared detector based on the indium phosphide substrate provided by the present invention.

[0021] Figure numerals: 1. N-type doped indium phosphide substrate; 2. Metal lower electrode; 3. Metal upper electrode; 4. Light hole; 5. Passivation layer; 6. Indium phosphide absorption layer; 7. First P-type contact layer; 8. Second P-type contact layer; 9. Short-wave infrared superlattice absorption layer; 10. N-type contact layer. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Combine the following Figures 1 to 3 The invention describes a short-wave dual-band infrared detector based on an indium phosphide substrate and a preparation method thereof.

[0024] One embodiment of the present invention provides a short-wave dual-band infrared detector based on an indium phosphide substrate, see Figure 1 As shown, the short-wave dual-band infrared detector includes an N-type doped indium phosphide substrate 1 and an epitaxial structure deposited on the N-type doped indium phosphide substrate 1. The epitaxial structure is etched into a cylindrical shape and forms a step structure with the N-type doped indium phosphide substrate 1. The step structure is provided with an annular metal lower electrode 2 at a position corresponding to the N-type doped indium phosphide substrate 1, and the step structure is provided with an annular metal upper electrode 3 at a position corresponding to the top of the epitaxial structure. A light-through hole 4 is formed in the center of the metal upper electrode 3. Except for the areas corresponding to the metal lower electrode 2, the metal upper electrode 3 and the light-through hole 4, the rest of the areas of the step structure are sequentially provided with a sulfide layer and a passivation layer 5.

[0025] The epitaxial structure includes an indium phosphide absorption layer 6, a first P-type contact layer 7, a second P-type contact layer 8, a short-wave infrared superlattice absorption layer 9 and an N-type contact layer 10. The indium phosphide absorption layer 6 is grown on an indium phosphide substrate 1; the first P-type contact layer 7 is grown on the indium phosphide absorption layer 6, and the first P-type contact layer 7 is doped with indium phosphide; the second P-type contact layer 8 is grown on the first P-type contact layer 7, and the second P-type contact layer 8 is doped with aluminum gallium arsenic antimony alloy; the short-wave infrared superlattice absorption layer 9 is grown on the second P-type contact layer 8; the N-type contact layer 10 is grown on the short-wave infrared superlattice absorption layer 9, and the N-type contact layer 10 is doped with indium gallium arsenide.

[0026] It can be understood that the structure of the short-wave dual-band infrared detector based on the indium phosphide substrate of this embodiment uses the N-type doped indium phosphide substrate 1 as the basis of the device, and can use a (100) crystal orientation sulfur (S) doped N-type InP substrate. The indium phosphide absorption layer 6 is directly grown on the N-type doped indium phosphide substrate 1, the first P-type contact layer 7 is grown on the indium phosphide absorption layer 6 and doped with indium phosphide; the second P-type contact layer 8 is grown on the first P-type contact layer 7 and doped with aluminum gallium arsenic antimony alloy (AlGaAsSb); the short-wave infrared superlattice absorption layer 9 is grown on the second P-type contact layer 8, and is formed by alternating stacking of multiple periods of InGaAs and / or GaAsSb; the N-type contact layer 10 is grown on the short-wave infrared superlattice absorption layer 9 and doped with InGaAs. The metal lower electrode 2 and the metal upper electrode 3 are both ring-shaped, and the metal lower electrode 2 is located at the position of the step structure corresponding to the N-type doped indium phosphide substrate 1, and is in contact with the substrate. The metal upper electrode 3 is located at the position of the step structure corresponding to the top of the epitaxial structure, and is in contact with the N-type contact layer 10. There is a light hole 4 in the center to allow light to enter the detector. The area outside the metal lower electrode 2, the metal upper electrode 3 and the light hole 4 is covered with a sulfide layer and a SiO2 passivation layer 5 to protect the epitaxial structure and reduce unnecessary surface states.

[0027] This embodiment utilizes the band gap characteristics of the N-type doped indium phosphide substrate 1 to participate in spectral absorption, converts it into an electrical signal for detection, and adopts a back-to-back diode structure, and can achieve different responses to short-wave dual-band infrared by adjusting the bias voltage. Since the N-type doped indium phosphide substrate 1 participates in light absorption, it is not necessary to remove the substrate as much as possible as in the traditional method, and it is only necessary to thin the substrate to between 100nm and 500nm. This embodiment uses the substrate as the device structure, which reduces the manufacturing cost and simplifies the process flow.

[0028] In some embodiments of the short-wave dual-band infrared detector based on an indium phosphide substrate of the present invention, the N-type doped indium phosphide substrate 1 uses a (100) crystal orientation sulfur-doped N-type indium phosphide substrate. The (100) crystal orientation is a commonly used crystal orientation in semiconductor materials, which can provide good crystal quality and help reduce the defect density during epitaxial growth, thereby improving device performance. Sulfur (S), as an N-type dopant, can adjust the conductivity type and concentration of the indium phosphide substrate, optimize the carrier concentration, improve the electrical properties, and facilitate the growth of subsequent epitaxial layers. Appropriate concentrations of S doping can also enhance the light absorption efficiency of the indium phosphide substrate, especially in the infrared band. In the present invention, the N-type doped indium phosphide substrate 1 will form a PN junction with the subsequently grown P-type layer, which is crucial for manufacturing a diode structure.

[0029] Unlike traditional infrared detectors that require the removal of the substrate to reduce its impact on light absorption efficiency, in the present invention, the N-type doped indium phosphide substrate 1 not only serves as the basis for epitaxial growth, but also directly participates in spectral absorption using its band gap characteristics, and is converted into electrical signals for detection. Since the substrate itself becomes part of the detector, it is not necessary to completely remove the substrate during the thinning process, which not only simplifies the device structure but also reduces production costs. By using a (100) crystal orientation sulfur-doped N-type indium phosphide substrate, the N-type doped indium phosphide substrate 1 can increase the absorption of light of a specific wavelength without affecting the main function of the detector, thereby improving the overall light response efficiency and detection sensitivity. Using (100) crystal orientation sulfur-doped N-type InP as the substrate material optimizes the overall performance of the detector, including but not limited to improving light absorption efficiency, simplifying the preparation process, and reducing costs, and plays an important role in realizing a high-efficiency short-wave dual-band infrared detector.

[0030] In some embodiments of the short-wave dual-band infrared detector based on an indium phosphide substrate of the present invention, the metal lower electrode 2 and the metal upper electrode 3 both include a titanium layer, a platinum layer and a gold layer from bottom to top, the titanium layer has a thickness of 20nm~80nm, the platinum layer has a thickness of 20nm~80nm, and the gold layer has a thickness of 250nm~400nm; the titanium layer of the metal lower electrode 2 is in contact with the N-type doped indium phosphide substrate 1, and the titanium layer of the metal upper electrode 3 is in contact with the N-type contact layer 10.

[0031] It is understood that in some specific examples, the titanium layer is 50nm thick, and the titanium layer serves as the bottom layer of the electrode, providing good adhesion, ensuring a stable contact between the metal electrode and the semiconductor material, and being able to form a low-resistance ohmic contact. The platinum layer is 50nm thick and is located above the titanium layer, which can improve the thermal and chemical stability of the entire metal layer and prevent the titanium layer from diffusing into the InP or N-type contact layer during high-temperature treatment, thereby ensuring the long-term reliability of the electrode performance. The gold layer is 300nm thick and, as the top layer, not only provides good conductivity, but also protects the internal titanium and platinum layers from environmental factors due to its excellent corrosion resistance.

[0032] The titanium layer of the metal lower electrode 2 is in direct contact with the N-type doped indium phosphide substrate 1, ensuring a good electrical connection from the substrate to the electrode, which helps to effectively collect and transmit the photogenerated carriers while maintaining a low contact resistance. The titanium layer of the metal upper electrode 3 is in contact with the N-type contact layer 10 in the epitaxial structure, playing a similar current collection role. A light hole 4 is left in the center of the ring-shaped metal upper electrode 3, allowing light to smoothly enter the effective area of ​​the detector to achieve efficient light absorption and conversion.

[0033] By selecting a suitable material combination and thickness ratio, this embodiment can achieve optimal ohmic contact of the electrode, reduce contact resistance, and improve the overall efficiency of the device. The good adhesion provided by the titanium layer and the high melting point characteristics brought by the platinum layer jointly enhance the mechanical strength and durability of the electrode under various processing conditions. The presence of the platinum layer effectively prevents the diffusion of titanium into the semiconductor material, especially in a high temperature environment, which is crucial for maintaining long-term stable electrical performance. The metal electrode structure of this embodiment plays a key role in ensuring that the short-wave dual-band infrared detector based on the indium phosphide substrate has high efficiency, high stability and long life.

[0034] In some embodiments of the short-wave dual-band infrared detector based on an indium phosphide substrate of the present invention, the indium phosphide absorption layer 6 has a thickness of 500nm to 2500nm and a band gap width of 1.34 to 1.35eV. The short-wave infrared superlattice absorption layer 9 is an indium gallium arsenide superlattice and / or an antimony gallium arsenide superlattice, and the short-wave infrared superlattice absorption layer 9 has a thickness of 500nm to 2500nm and a band gap width of 1.34 to 1.35eV.

[0035] It is understandable that the indium phosphide absorption layer 6 is directly grown on the N-type doped indium phosphide substrate 1. As the first light absorption layer of the detector, the band gap width of this layer determines that it can effectively absorb photons within a specific wavelength range and convert them into electron-hole pairs. Indium phosphide material has good absorption efficiency for short-wave infrared light within this band gap range, which makes it particularly suitable for short-wave dual-band infrared detection applications. The short-wave infrared superlattice absorption layer 9 is located on the second P-type contact layer 8 and is the key part of the detector responsible for absorbing infrared light in another band. By selecting an appropriate InGaAs or GaAsSb superlattice structure, its band gap width can be precisely controlled to match the target detection wavelength. This superlattice structure can provide additional quantum confinement effects, thereby enhancing the absorption efficiency of light of a specific wavelength, while maintaining a low dark current level and improving the signal-to-noise ratio.

[0036] In some embodiments of the shortwave dual-band infrared detector based on an indium phosphide substrate of the present invention, the shortwave infrared superlattice absorption layer 9 includes a plurality of indium gallium arsenide superlattice layers and a plurality of antimony gallium arsenide superlattice layers, and the plurality of indium gallium arsenide superlattice layers and the plurality of antimony gallium arsenide superlattice layers are cross-stacked and grown to form the shortwave infrared superlattice absorption layer 9.

[0037] It can be understood that this embodiment forms a multi-layer cross-stacked structure by alternately growing InGaAs superlattice layers and GaAsSb superlattice layers, and the superlattice layers of each material have a specific thickness and periodicity to achieve the required bandgap engineering. InGaAs and GaAsSb have complementary optical and electrical properties. InGaAs has a better absorption efficiency for shorter wavelength infrared light, while GaAsSb can effectively absorb longer wavelength infrared light. The combination of the two can expand the absorption spectrum range and cover a wider short-wave infrared region. The thickness and stacking period of each superlattice layer are precisely designed to ensure that the bandgap width of the entire short-wave infrared superlattice absorption layer 9 is maintained between 1.34 and 1.35 eV, thereby optimizing the absorption efficiency of infrared light in the target band.

[0038] In this embodiment, by cross-stacking two materials with different band gap widths, InGaAs and GaAsSb, effective detection of two different short-wavelength infrared light bands can be achieved in a single device, which not only increases the application flexibility of the detector, but also improves the imaging quality and target recognition ability. The superlattice structure introduces the quantum confinement effect, that is, electrons and holes are confined to one or several quantum wells, which can enhance the absorption of photons of a specific wavelength, while reducing the number of thermally generated carriers, reducing dark current, and improving the signal-to-noise ratio. Due to the existence of the quantum confinement effect, the detector can operate at a lower temperature and have a lower dark current level, which is particularly important for weak signal detection. The superlattice structure of this embodiment makes the detector more sensitive to photons in the target band while maintaining a high spatial resolution, and is suitable for a variety of high-precision infrared imaging and sensing applications. InGaAs and GaAsSb materials are highly compatible with existing semiconductor manufacturing processes, allowing the use of mature epitaxial growth technologies such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) to prepare these complex superlattice structures, thereby ensuring the feasibility of large-scale production.

[0039] Another aspect of the present invention further provides a method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate, which is suitable for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate in any of the above embodiments. In some specific embodiments of the method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate, Figure 2 As shown, the preparation process includes the following steps S1 to S10.

[0040] S1, using an N-type doped indium phosphide substrate 1 as a structural substrate of an infrared detector, and performing degassing and deoxidation pretreatment on the N-type doped indium phosphide substrate 1. The purpose of this step is to ensure that the surface of the N-type doped indium phosphide substrate 1 is clean and to remove oxides and other contaminants. Specifically, the N-type doped indium phosphide substrate 1 is first placed in the sample chamber of the molecular beam epitaxy system, maintained at a temperature of 200°C, and subjected to low-temperature degassing for 150 minutes; then the N-type doped indium phosphide substrate 1 that has completed low-temperature degassing is transferred to the buffer chamber of the molecular beam epitaxy system, maintained at a temperature of 360°C, and subjected to high-temperature degassing for 60 minutes to 100 minutes; finally, the N-type doped indium phosphide substrate 1 that has completed high-temperature degassing is transferred to the growth chamber of the molecular beam epitaxy system, and the N-type doped indium phosphide substrate 1 is gradually heated to 500°C to 700°C, and subjected to deoxidation treatment for 15 minutes to 30 minutes to remove oxides on the surface of the N-type doped indium phosphide substrate 1.

[0041] S2 . Based on the pre-treated N-type doped indium phosphide substrate 1 , homoepitaxially grow an indium phosphide absorption layer 6 on the N-type doped indium phosphide substrate 1 .

[0042] The purpose of this step is to provide a high-quality base layer before epitaxial growth. Specifically, a 1500 nm thick indium phosphide absorption layer 6 is homoepitaxially grown on the N-type doped indium phosphide substrate 1 after the deoxidation treatment in step S1 at a growth rate of 0.5 ML / s.

[0043] S3 . Growing a first P-type contact layer 7 on the indium phosphide absorption layer 6 .

[0044] The purpose of this step is to form a good electrical contact and serve as a support for subsequent layers. Specifically, a 300nm first P-type contact layer 7 is then grown on the indium phosphide absorption layer 6 grown in step S2. The first P-type contact layer 7 is doped with InP and has a growth rate of 0.5ML / s.

[0045] S4 , growing a second P-type contact layer 8 on the first P-type contact layer 7 .

[0046] The purpose of this step is to further optimize the electrical performance and prepare to grow the short-wave infrared superlattice absorption layer 9. Specifically, a 500 nm thick second P-type contact layer 8 is then grown on the first P-type contact layer 7 in step S3, and the second P-type contact layer 8 is doped with AlGaAsSb.

[0047] S5 . Growing a short-wave infrared superlattice absorption layer 9 on the second P-type contact layer 8 .

[0048] The purpose of this step is to construct an absorption region that is sensitive to light of a specific wavelength. Specifically, a short-wave infrared superlattice absorption layer 9 with a thickness of 2000 nm is then grown on the second P-type contact layer 8 in step S4, wherein the short-wave infrared superlattice absorption layer 9 is a stacked structure of a layer of InGaAs with a thickness of d1 and a layer of GaAsSb with a thickness of d2, and d1+d2 is regarded as a period, and the growth is repeated for n periods to obtain a short-wave infrared superlattice absorption layer 9 with precisely controlled composition.

[0049] S6 . Growing an N-type contact layer 10 on the short-wave infrared superlattice absorption layer 9 .

[0050] The purpose of this step is to provide a final electron collection layer and form a good contact with the metal upper electrode. Specifically, a 100 nm N-type contact layer 10 is then grown on the short-wave infrared superlattice absorption layer 9 in step S5, and the N-type contact layer 10 is doped with InGaAs.

[0051] S7. An epitaxial structure composed of an indium phosphide absorption layer 6, a first P-type contact layer 7, a second P-type contact layer 8, a short-wave infrared superlattice absorption layer 9 and an N-type contact layer 10 is deposited on an N-type doped indium phosphide substrate 1, and the side of the epitaxial structure is etched by inductively coupled plasma ICP to make the epitaxial structure cylindrical.

[0052] The purpose of this step is to process the epitaxial structure into the desired cylindrical shape by etching. Specifically, the side of the epitaxial structure deposited on the N-type doped indium phosphide substrate 1 prepared in step S6 is etched by inductively coupled plasma ICP to form a step, so that the remaining epitaxial structure is cylindrical, and the etching gas used is CH4:Cl2:Ar or CH4:Cl2:BCl3:Ar or Cl2:BCl3:Ar in a suitable ratio, and the depth of the step is 4700nm, and the step is deep to the N-type doped indium phosphide substrate 1.

[0053] S8, covering the N-type doped indium phosphide substrate 1 and the epitaxial structure with a sulfide layer and a passivation layer 5.

[0054] The purpose of this step is to protect the epitaxial structure and reduce the influence of the surface state. Specifically, a 300 nm thick sulfide layer and a SiO2 passivation layer 5 are prepared by plasma chemical vapor deposition to cover the device etched in step S7.

[0055] S9. Use photolithography to prepare a mask at a position of the passivation layer 5 corresponding to the N-type doped indium phosphide substrate 1, and form a first annular opening by reactive ion etching. Use photolithography to prepare a mask at a position of the passivation layer 5 corresponding to the N-type contact layer 10, and form a second annular opening by reactive ion etching.

[0056] The purpose of this step is to prepare for the subsequent evaporation of electrodes. Specifically, the SiO2 passivation layer 5 prepared on the surface of the epitaxial structure in step S8 is subjected to a hole-opening process, a mask is prepared using photolithography, and a hole is etched by reactive ion etching (RIE), and the processing range is the preset metal lower electrode 2, metal upper electrode 3 and light-through hole 4.

[0057] S10, performing evaporation electrode processing on the first annular opening to form an annular metal lower electrode 2; performing evaporation electrode processing on the second annular opening to form an annular metal upper electrode 3 and a light-through hole 4.

[0058] The purpose of this step is to form a metal electrode for electrical connection. Specifically, the metal upper electrode and the metal lower electrode ranges respectively located on the upper and lower terraces of the step preset in step S9 are subjected to electrode evaporation treatment, and the metal lower electrode 2 and the metal upper electrode 3 are formed of Ti / Pt / Au by electron beam evaporation, and the thicknesses are 50nm / 50nm / 300nm respectively, wherein the metal upper electrode 3 is annular, formed on the upper terrace of the step, and the Ti layer is in contact with the short-wave infrared N-type contact layer 10, and the metal lower electrode 2 is annular, formed on the lower terrace of the step, and the Ti layer is in contact with the S-doped N-type doped indium phosphide substrate 1.

[0059] In summary, the method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate of the present embodiment ensures that the short-wave dual-band infrared detector based on an indium phosphide substrate has the characteristics of high efficiency, high stability and long life through a series of precisely controlled process steps, from substrate pretreatment to the formation of the final electrode. Each step is carefully designed to achieve the best material quality and device performance, thereby meeting the needs of high-performance infrared detection. The short-wave dual-band infrared detector based on an indium phosphide substrate prepared by the method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate of the present embodiment utilizes the band gap characteristics of the N-type doped indium phosphide substrate 1 itself to participate in spectral absorption, which is converted into an electrical signal for detection. At the same time, a back-to-back diode structure is adopted, and different responses to short-wave dual-band infrared can be achieved by adjusting the bias voltage, see. Figure 3 The spectral response diagram of the short-wave dual-band infrared detector based on the indium phosphide substrate is shown. The short-wave dual-band infrared detector based on the indium phosphide substrate can respond to the first infrared short-wave band with a wavelength of 0.7μm~0.9μm, and can also respond to the second infrared short-wave band with a wavelength of 1.4μm~2.8μm. Since the N-type doped indium phosphide substrate 1 participates in light absorption, it is not necessary to remove the substrate as in the traditional method, thereby reducing the production cost and simplifying the process flow.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A short-wave dual-band infrared detector based on an indium phosphide substrate, characterized in that: The invention comprises an N-type doped indium phosphide substrate (1) and an epitaxial structure deposited on the N-type doped indium phosphide substrate (1), the epitaxial structure being etched into a cylindrical shape and forming a step structure with the N-type doped indium phosphide substrate (1), the step structure being provided with an annular metal lower electrode (2) at a position corresponding to the N-type doped indium phosphide substrate (1), the step structure being provided with an annular metal upper electrode (3) at a position corresponding to the top of the epitaxial structure, a light-through hole (4) being formed at the center of the metal upper electrode (3), and the step structure being provided with a sulfide layer and a passivation layer (5) in sequence in all regions except the regions corresponding to the metal lower electrode (2), the metal upper electrode (3) and the light-through hole (4); The epitaxial structure comprises: An indium phosphide absorption layer (6) grown on the indium phosphide substrate (1); A first P-type contact layer (7) grown on the indium phosphide absorption layer (6), wherein the first P-type contact layer (7) is doped with indium phosphide; A second P-type contact layer (8) grown on the first P-type contact layer (7), the second P-type contact layer (8) being doped with an aluminum-gallium-arsenic-antimony alloy; A short-wave infrared superlattice absorption layer (9) grown on the second P-type contact layer (8); An N-type contact layer (10) is grown on the short-wave infrared superlattice absorption layer (9), and the N-type contact layer (10) is doped with gallium arsenide indium.

2. The short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 1, characterized in that: The N-type doped indium phosphide substrate (1) uses a (100) crystal orientation sulfur-doped N-type indium phosphide substrate.

3. The short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 1, characterized in that: The metal lower electrode (2) and the metal upper electrode (3) both comprise, from bottom to top, a titanium layer, a platinum layer and a gold layer, the titanium layer having a thickness of 20 nm to 80 nm, the platinum layer having a thickness of 20 nm to 80 nm, and the gold layer having a thickness of 250 nm to 400 nm; the titanium layer of the metal lower electrode (2) contacts the N-type doped indium phosphide substrate (1), and the titanium layer of the metal upper electrode (3) contacts the N-type contact layer (10).

4. The short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 1, characterized in that: The indium phosphide absorption layer (6) has a thickness of 500 nm to 2500 nm and a band gap width of 1.34 to 1.35 eV.

5. The short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 1, characterized in that: The short-wave infrared superlattice absorption layer (9) is a gallium arsenide indium superlattice and / or a gallium arsenide antimony superlattice, and the short-wave infrared superlattice absorption layer (9) has a thickness of 500 nm to 2500 nm and a band gap width of 1.34 to 1.35 eV.

6. The short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 5, characterized in that: The short-wave infrared superlattice absorption layer (9) comprises a plurality of indium gallium arsenide superlattice layers and a plurality of antimony gallium arsenide superlattice layers, and the plurality of indium gallium arsenide superlattice layers and the plurality of antimony gallium arsenide superlattice layers are cross-stacked and grown to form the short-wave infrared superlattice absorption layer (9).

7. A method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate, characterized in that: Suitable for preparing the short-wave dual-band infrared detector based on an indium phosphide substrate as described in any one of claims 1 to 6, comprising: Using an N-type doped indium phosphide substrate (1) as a structural substrate of an infrared detector, and performing a degassing and deoxidation pretreatment on the N-type doped indium phosphide substrate (1); Based on the pre-treated N-type doped indium phosphide substrate (1), homoepitaxially growing an indium phosphide absorption layer (6) on the N-type doped indium phosphide substrate (1); Growing a first P-type contact layer (7) on the indium phosphide absorption layer (6); Growing a second P-type contact layer (8) on the first P-type contact layer (7); Growing a short-wave infrared superlattice absorption layer (9) on the second P-type contact layer (8); Growing an N-type contact layer (10) on the short-wave infrared superlattice absorption layer (9); An epitaxial structure is deposited on the N-type doped indium phosphide substrate (1) based on the indium phosphide absorption layer (6), the first P-type contact layer (7), the second P-type contact layer (8), the short-wave infrared superlattice absorption layer (9) and the N-type contact layer (10), and the side surface of the epitaxial structure is etched by inductively coupled plasma (ICP) so that the epitaxial structure is cylindrical; Covering the N-type doped indium phosphide substrate (1) and the epitaxial structure with a sulfide layer and a passivation layer (5); Using photolithography to prepare a mask at a location on the passivation layer (5) corresponding to the N-type doped indium phosphide substrate (1), forming a first annular opening by reactive ion etching, and using photolithography to prepare a mask at a location on the passivation layer (5) corresponding to the N-type contact layer (10), forming a second annular opening by reactive ion etching; The first annular opening is subjected to an evaporation electrode process to form an annular metal lower electrode (2); and the second annular opening is subjected to an evaporation electrode process to form an annular metal upper electrode (3) and a light-through hole (4).

8. The method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 7, characterized in that: The pretreatment of degassing and deoxidizing the N-type doped indium phosphide substrate (1) comprises: Placing the N-type doped indium phosphide substrate (1) in a molecular beam epitaxy system injection chamber, maintaining the temperature at 200° C., and performing low-temperature degassing for 150 minutes; The N-type doped indium phosphide substrate (1) that has completed low-temperature degassing is transferred into a buffer chamber of a molecular beam epitaxy system, maintained at a temperature of 360° C., and subjected to high-temperature degassing for 60 min to 100 min; The N-type doped indium phosphide substrate (1) that has completed high-temperature degassing is transferred into a growth chamber of a molecular beam epitaxy system, the temperature of the N-type doped indium phosphide substrate (1) is gradually raised to 500° C. to 700° C., and a deoxidation treatment is performed for 15 min to 30 min to remove oxides on the surface of the N-type doped indium phosphide substrate (1).

9. The method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 7, characterized in that: The indium phosphide absorption layer (6) has a growth rate of 0.5 ML / s, and the thickness of the grown indium phosphide absorption layer (6) is 500 nm to 2500 nm; The growth rate of the first P-type contact layer (7) is 0.5 ML / s, and the thickness of the grown first P-type contact layer (7) is 200 nm to 400 nm; The growth rate of the second P-type contact layer (8) is 0.5 ML / s, and the thickness of the grown second P-type contact layer (8) is 400 nm to 600 nm; The growth rate of the short-wave infrared superlattice absorption layer (9) is 0.5 ML / s, and the thickness of the grown short-wave infrared superlattice absorption layer (9) is 500 nm to 2500 nm; The growth rate of the N-type contact layer (10) is 0.5 ML / s, and the thickness of the grown N-type contact layer (10) is 7000 nm to 150 nm.

10. The method for preparing a short-wave dual-band infrared detector based on an indium phosphide substrate according to claim 7, characterized in that: The step of subsequently growing a short-wave infrared superlattice absorption layer (9) on the second P-type contact layer (8) comprises: Growing a GaAs indium superlattice layer on the second P-type contact layer (8), and growing a GaAs antimony superlattice layer on the grown GaAs indium superlattice layer; Taking the grown indium gallium arsenide superlattice layer and the antimony gallium arsenide superlattice layer as a periodic unit, a plurality of periodic units are repeatedly grown upwards until the total thickness of all periodic units reaches 500nm to 2500nm, thereby forming the short-wave infrared superlattice absorption layer (9).

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