A germanium-based multi-junction dual-color long-wave infrared detector and a preparation method thereof

Abstract

The present application relates to the technical field of semiconductor devices, in particular to a germanium-based multi-junction dual-color long-wave infrared detector and a preparation method thereof, which comprises a germanium substrate, an electrode injection region arranged on the surface of the germanium substrate, a plurality of barrier regions, a plurality of first single-color absorption regions and a plurality of second single-color absorption regions, a common electrode arranged on the electrode injection region, a plurality of first absorption region electrodes and a plurality of second absorption region electrodes, a passivation layer arranged on the plurality of barrier regions, the plurality of first single-color absorption regions and the plurality of second single-color absorption regions, the plurality of first single-color absorption regions and the plurality of barrier regions are located between the common electrode and the plurality of first absorption region electrodes and are periodically distributed, and the plurality of second single-color absorption regions and the plurality of barrier regions are located between the common electrode and the plurality of second absorption region electrodes and are periodically distributed. The present application can help to improve the detection rate and realize dual-color detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices, in particular to a germanium-based multi-junction dual-color long-wave infrared detector and a preparation method thereof. BACKGROUND

[0002] Infrared astronomy is an important branch of astronomy, and its development depends on the progress of infrared detectors. Currently, common infrared detectors are mainly made of materials such as mercury cadmium telluride, indium antimonide and indium gallium arsenide. These materials all use the intrinsic absorption characteristics of semiconductors to detect infrared light, but the longest wavelength that can be detected is limited by the band gap of the material itself, which cannot meet the demand for longer wavelengths in infrared astronomy. In addition, a single detector corresponds to only one fixed waveband, and multiple single-color detectors need to be combined with a complex optical system to achieve multi-color detection, resulting in high cost.

[0003] Unlike the above-mentioned detectors, the blocked impurity band detector introduces energy levels by doping impurities into semiconductor materials and uses the impurity energy level to absorb infrared light for detection. The response wavelength of such a detector depends on the ionization activation energy of the impurity, and the waveband range that can be detected can be expanded by selecting different doping impurities. For example, the response range of a silicon-based detector can reach 2-50 μm, while the response range of a germanium-based and gallium arsenide-based detector can extend to 200 μm and 300 μm, respectively. The blocked impurity band detector has outstanding long-wave detection advantages in the field of mid-infrared and far-infrared astronomy, and has become the mainstream detector.

[0004] However, the blocked impurity band detector of the traditional structure also has limitations in detection performance. Theoretical analysis shows that the electric field in the absorption region of the device is only concentrated in a very narrow depletion region, and the electric field is very weak in the remaining neutral region. This results in only the photo-generated carriers generated in the depletion region contributing to the effective signal. However, it is difficult to further widen the depletion region under the existing process. In addition, the traditional structure can only perform single-color detection. With the increasing demand for detection performance, such as improving the detection rate and achieving multi-color detection, it is necessary to optimize and improve the existing detector structure to meet new demands.

[0005] Therefore, the conventional BIB detector (Blocked Impurity Band detector) has the technical problem of low device quantum efficiency, and cannot realize dual-color detection. Furthermore, the preparation cost is difficult to further reduce. SUMMARY

[0006] In order to optimize the technical problem of low device quantum efficiency caused by the narrow depletion layer of the conventional BIB detector, the present application provides a germanium-based multi-junction dual-color long-wave infrared detector and a preparation method thereof.

[0007] The application provides a germanium-based multi-junction dual-color long-wave infrared detector.

[0008] A germanium-based multi-junction dual-color long-wave infrared detector comprises a germanium substrate.

[0009] An electrode injection region, a plurality of barrier regions, a plurality of first single-color absorption regions and a plurality of second single-color absorption regions are arranged on the surface of the germanium substrate.

[0010] A common electrode, a plurality of first absorption region electrodes and a plurality of second absorption region electrodes are arranged on the electrode injection region.

[0011] A passivation layer is arranged on the plurality of barrier regions, the plurality of first single-color absorption regions and the plurality of second single-color absorption regions.

[0012] The plurality of first single-color absorption regions and the plurality of barrier regions are located between the common electrode and the plurality of first absorption region electrodes and are periodically distributed.

[0013] The plurality of second single-color absorption regions and the plurality of barrier regions are located between the common electrode and the plurality of second absorption region electrodes and are periodically distributed.

[0014] The first single-color absorption region (4) and the second single-color absorption region (5) are both degenerate-doped germanium materials, and the first single-color absorption region (4) and the second single-color absorption region (5) are different in the type of doped impurities.

[0015] In a specific implementable embodiment, the electrode injection region, the barrier region, the first single-color absorption region and the second single-color absorption region are all located in the near-surface of the germanium substrate, and the depth of the surface of the germanium substrate is 0.1 μm-3 μm.

[0016] In a specific implementable embodiment, the ratio of the number of the first single-color absorption region, the second single-color absorption region and the barrier region is 1:1:2.

[0017] In a specific implementable embodiment, the number of the first single-color absorption region + the number of the second single-color absorption region = the number of the barrier region.

[0018] The result of (the number of the first single-color absorption region x the width of the first single-color absorption region) + (the number of the second single-color absorption region x the width of the second single-color absorption region) is a constant value.

[0019] In a specific implementable embodiment, the germanium substrate is a high-resistance germanium substrate, and the impurity concentration ranges from 1x10 12 to 1x10 14 cm -3 .

[0020] In one specific embodiment, the doping element of the first single-color absorption region is one or more of boron, gallium, beryllium, phosphorus or sulfur, the impurity concentration ranges from 1x10 16 to 1x10 17 cm -3 , the doping depth ranges from 0.1 μm to 3 μm, and the width ranges from 5 μm to 50 μm.

[0021] The doping element of the second single-color absorption region is one or more of boron, gallium, beryllium, phosphorus or sulfur, the impurity concentration ranges from 1x10 16 to 1x10 17 cm -3 , the doping depth ranges from 0.1 μm to 3 μm, and the width ranges from 5 μm to 50 μm.

[0022] In one specific embodiment, the electrode implantation region is a degenerate doped germanium material doped with one or more impurities of boron, gallium, beryllium or phosphorus, the concentration of the impurities ranges from 1x10 18 to 1x10 19 cm -3 , the doping depth ranges from 0.1 μm to 3 μm, and the width ranges from 5 μm to 50 μm.

[0023] The present application also provides a germanium-based multi-junction dual-color long-wave infrared detector, which adopts the following technical scheme:

[0024] A preparation method of a germanium-based multi-junction dual-color long-wave infrared detector, which is used for preparing the above-mentioned germanium-based multi-junction dual-color long-wave infrared detector, and comprises the following steps:

[0025] forming a pattern of a plurality of the first single-color absorption regions on the surface of the germanium substrate, and then implanting impurities into the pattern by using an ion implantation process to form a plurality of the first single-color absorption regions;

[0026] forming a pattern of a plurality of the second single-color absorption regions on the surface of the germanium substrate, and then implanting impurities into the pattern by using an ion implantation process to form a plurality of the second single-color absorption regions;

[0027] forming a pattern of the electrode implantation region on the surface of the germanium substrate, and then implanting impurities into the pattern by using an ion implantation process to form the electrode implantation region;

[0028] depositing the passivation layer on the surface of the germanium substrate by using a plasma-enhanced chemical vapor deposition process, and then performing a heat treatment to activate the implanted impurities;

[0029] making electrode holes on the passivation layer by using a wet etching process, and then forming the common electrode, a plurality of the first absorption region electrodes and a plurality of the second absorption region electrodes by using a metal deposition process.

[0030] In one specific implementation, the doping concentration of the germanium substrate is 1 × 10⁻⁶. 12 cm -3 The number of first monochromatic absorption regions is two, each with a width of 50 μm, and the spacing between adjacent first monochromatic absorption regions is 10 μm; gallium is implanted into the first monochromatic absorption regions to a doping depth of 3 μm and a doping concentration of 1 × 10⁻⁶. 17 cm -3 The second monochromatic absorption region consists of two regions, each 50 μm wide, with a spacing of 10 μm between adjacent regions. Gallium is implanted into the second monochromatic absorption region to a doping depth of 3 μm and a doping concentration of 1 × 10 cm⁻¹. -3 The electrode implantation region has a width of 50 μm and is doped with boron to a depth of 3 μm at a doping concentration of 1 × 10⁻⁶. 19 cm -3 .

[0031] In one specific implementation, the doping concentration of the germanium substrate is 1 × 10⁻⁶. 13 cm -3 The number of first monochromatic absorption regions is 4, each with a width of 20 μm, and the spacing between adjacent first monochromatic absorption regions is 5 μm; gallium is implanted into the first monochromatic absorption regions to a doping depth of 0.5 μm and a doping concentration of 5 × 10⁻⁶. 16 cm -3 The second monochromatic absorption region comprises four regions, each 20 μm wide, with a spacing of 5 μm between adjacent regions. Boron is implanted into the second monochromatic absorption region to a doping depth of 1 μm and a doping concentration of 5 × 10⁻⁶. 16 cm -3 The electrode implantation region has a width of 25 μm, and is doped with boron to a depth of 1 μm at a concentration of 3 × 10⁻⁶. 18 cm -3 .

[0032] In one specific implementation, the doping concentration of the germanium substrate is 1 × 10⁻⁶. 14 cm -3 The number of first monochromatic absorption regions is 5, the width is 5 μm, and the spacing between adjacent first monochromatic absorption regions is 3 μm; boron is implanted into the first monochromatic absorption regions to a doping depth of 0.1 μm and a doping concentration of 1 × 10⁻⁶. 16 cm -3 The second monochromatic absorption region comprises five regions, each 5 μm wide, with a spacing of 3 μm between adjacent regions. Gallium is implanted into the second monochromatic absorption region to a doping depth of 0.1 μm and a doping concentration of 1 × 10⁻⁶. 16 cm -3The electrode injection area has a width of 5 microns, boron is doped therein, the doping depth is 0.1 microns, and the doping concentration is 1*10 18 cm -3 .

[0033] In summary, the present application includes the following advantages:

[0034] The present application greatly improves the quantum efficiency and enhances the detection capability. Dual-band detection is achieved, which expands the application range. The structure is simplified, and the manufacturing difficulty and cost are reduced. The present application is compatible with mainstream semiconductor processes and is easy to popularize and apply. The present application not only inherits the advantages of BIB detection of long-wave infrared, but also solves the problems of low quantum efficiency and narrow detection range. The present application is suitable for silicon-based and gallium arsenide-based devices and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of the overall structure of the germanium-based barrier impurity dual-color long-wave infrared light detector.

[0036] Figure 2 is a flowchart of the preparation method of the germanium-based barrier impurity dual-color long-wave infrared light detector.

[0037] Figure 3 is a schematic diagram of the specific structure of the dual-color long-wave infrared light detector in Example 1.

[0038] Figure 4 is a schematic diagram of the specific structure of the dual-color long-wave infrared light detector in Example 2.

[0039] Figure 5 is a schematic diagram of the specific structure of the dual-color long-wave infrared light detector in Example 3.

[0040] Figure 6 shows a schematic diagram of the ion implantation process for forming the first monochromatic absorption region.

[0041] Figure 7 shows a schematic diagram of the ion implantation process for forming the second monochromatic absorption region.

[0042] Figure 8 shows a schematic diagram of the ion implantation process for forming the electrode injection area.

[0043] Figure 9 shows a schematic diagram of the process of opening the electrode hole.

[0044] BRIEF DESCRIPTION OF DRAWINGS: 1, germanium substrate; 2, electrode injection area; 3, barrier region; 4, first monochromatic absorption region; 5, second monochromatic absorption region; 6, common electrode; 7, passivation layer; 8, first absorption region electrode; 9, second absorption region electrode. DETAILED DESCRIPTION

[0045] The following description is made in connection with Figures 1-9 The present application is further described in detail.

[0046] Referring to Figure 1 , the germanium-based multijunction dual-color long-wave infrared detector includes a germanium substrate 1, which is specifically a high-resistance germanium substrate, and the impurity concentration range is 1×10 12 -1×10 14 cm -3 -2. The response wavelength of the germanium substrate 1 can reach more than 50 μm, which improves the performance of the infrared detector, makes it suitable for high-impedance scenes, and realizes a wider waveband detection function.

[0047] A plurality of first monochromatic absorption zones 4, second monochromatic absorption zones 5, electrode injection zones 2, and barrier zones 3 are made on the germanium substrate 1 by ultraviolet lithography. Among them, the first monochromatic absorption zone 4 and the second monochromatic absorption zone 5 are both degenerate doped germanium materials, and are both located in the near surface of the germanium substrate 1.

[0048] The doping element of the first monochromatic absorption zone 4 is one or more of boron, gallium, beryllium, phosphorus, or sulfur, and the impurity concentration range is 1×10 16 -1×10 17 cm -3 -2, the doping depth range is 0.1 μm to 3 μm, and the width range is 5 μm to 50 μm.

[0049] The doping element of the second monochromatic absorption zone 5 is one or more of boron, gallium, beryllium, phosphorus, or sulfur, and the impurity concentration range is 1×10 16 -1×10 17 cm -3 -2, the doping depth range is 0.1 μm to 3 μm, and the width range is 5 μm to 50 μm. It should be noted that the doping impurity types of the plurality of first monochromatic absorption zones 4 are the same, the doping impurity types of the plurality of second monochromatic absorption zones 5 are the same, but the doping impurity types of the first monochromatic absorption zone 4 and the second monochromatic absorption zone 5 are different.

[0050] The electrode injection zone 2 and the barrier zone 3 are both located in the near surface of the germanium substrate 1, and the depth of the surface of the germanium substrate 1 is 0.1 μm to 3 μm.

[0051] The electrode injection zone 2 is a degenerate doped germanium material doped with one or more impurities of boron, gallium, beryllium, or phosphorus, and the concentration of the impurities is 1×10 18 -1×10 19 cm -3 -2, the doping depth is 0.1 μm to 3 μm, and the width is 5 μm to 50 μm.

[0052] The barrier zone 3 is a high-resistance germanium material, and the width range is 3 μm to 10 μm.

[0053] A passivation layer 7 is deposited on the blocking region 3, the first monochromatic absorption region 4 and the second monochromatic absorption region 5.

[0054] A common electrode 6, a first absorption region electrode 8 and a second absorption region electrode 9 are deposited on the electrode injection region 2, the first absorption region electrode 8 and the second absorption region electrode 9 are distributed on the opposite ends of the common electrode 6, and the passivation layer 7 is between the first absorption region electrode 8 and the second absorption region electrode 9 and the common electrode 6.

[0055] Further, the first monochromatic absorption region 4 and the blocking region 3 are periodically distributed below the common electrode 6 and the first absorption region electrode 8, that is, the first monochromatic absorption region 4 and the blocking region 3 are staggered. The second monochromatic absorption region 5 and the plurality of blocking regions 3 are periodically distributed below the common electrode 6 and the second absorption region electrode 9, that is, the second monochromatic absorption region 5 and the blocking region 3 are staggered.

[0056] In addition, the ratio of the number of the first monochromatic absorption region 4, the second monochromatic absorption region 5 and the blocking region 3 is 1:1:2; that is, the dual-color long-wave infrared detector has n first monochromatic absorption regions 4, n second monochromatic absorption regions 5 and 2n blocking regions 3, wherein 2≤n≤5, n∈R. Each first monochromatic absorption region 4 or second monochromatic absorption region 5 has n depletion regions.

[0057] The widths of the first monochromatic absorption region 4, the second monochromatic absorption region 5 and the blocking region 3 are associated, mainly in the design of the infrared detector, it is hoped that in the limited area, the largest absorption area is realized as much as possible, therefore, in the design, it is mainly considered to split the wide blocking region into multiple narrow blocking regions to adjust the performance, that is, the number of the first monochromatic absorption region 4+the number of the second monochromatic absorption region 5=the number of the blocking region 3, and it is hoped that the absorption area is as unchanged as possible, that is, the result of (the number of the first monochromatic absorption region 4×the width of the first monochromatic absorption region 4)+(the number of the second monochromatic absorption region 5×the width of the second monochromatic absorption region 5) is basically a constant value.

[0058] In the infrared detector, the first monochromatic absorption region 4 and the second monochromatic absorption region 5 realize the absorption of light and the generation of corresponding light response current (photocurrent) through doped impurities, but the first monochromatic absorption region 4 and the second monochromatic absorption region 5 will also generate current (dark current) when not receiving light; by introducing an undoped high-purity blocking region 3, part of the dark current can be inhibited by the blocking region 3, and the inhibition effect depends on the width of the blocking region 3, but too large width will affect the photocurrent while inhibiting the dark current, by splitting the blocking region 3, the influence of the blocking layer on the photocurrent can be reduced while retaining good dark current inhibition effect, and the detection efficiency is optimized.

[0059] In the traditional production process, the blocking region 3, the first single-color absorption region 4 and the second single-color absorption region 5 are all formed by performing semiconductor homo-epitaxy of a new semiconductor thin film on the substrate, which has a high difficulty and risk in vertical direction epitaxy and has important production process difficulties. In the present application, the blocking region 3, the first single-color absorption region 4 and the second single-color absorption region 5 are formed by ion implantation and doping on the high-purity germanium substrate 1, and the process step does not encounter the difficulties encountered by homo-epitaxy, so that the first single-color absorption region 4 and the second single-color absorption region 5 and the plurality of blocking regions 3 can be realized. Since the first single-color absorption region 4 and the second single-color absorption region 5 are at different positions in the device plane, the light interference between the first single-color absorption region 4 and the second single-color absorption region 5 is reduced, and the electrical interference caused by the incident light is difficult to reach the electrode on the other side through the common electrode 6, thereby ensuring a lower electrical interference.

[0060] By precisely setting the electrode implantation region 2, the blocking region 3, the first single-color absorption region 4 and the second single-color absorption region 5 on the germanium substrate 1, and the corresponding first absorption region electrode 8, the second absorption region electrode 9 and the passivation layer 7, a high-efficiency dual-color detection is realized.

[0061] Embodiment 1:

[0062] As shown in Figure 3 , the preparation method of the germanium-based multi-junction dual-color long-wave infrared detector of the present example includes the following steps:

[0063] Step 110: Select a high-resistance germanium substrate 1 as a substrate, and the doping concentration of the germanium substrate 1 is 1×10 12 cm⁻³. Use ultraviolet lithography technology to make two patterns of the first single-color absorption region 4 on the surface of the germanium substrate 1. The width of each first single-color absorption region 4 is set to 50 μm, and the width of the blocking region 3 between the two first single-color absorption regions 4 is set to 10 μm. When making the pattern of the first single-color absorption region 4, a photoresist with a thickness of about 3 μm is used as a masking layer, which can play a masking role in the subsequent ion implantation process.

[0064] Step 120: Boron (B) impurities are implanted into the first single-color absorption region 4 through multiple ion implantation processes. The implantation depth of boron is about 3 μm, and the doping concentration is about 1×10 17 cm -3 .

[0065] Step 130: Again use ultraviolet lithography technology to make two patterns of the second single-color absorption region 5 on the surface of the germanium substrate 1. The width of each second single-color absorption region 5 is set to 50 μm, and the width of the blocking region 3 between the two second single-color absorption regions 5 is set to 10 μm.

[0066] Step 140: Again, by multiple ion implantation process, gallium (Ga) impurities are implanted into the second monochromatic absorption region 5. The implantation depth of gallium is about 3 μm, and the doping concentration is about 1 x 10 17 cm -3 .

[0067] Step 150: Again, by using ultraviolet lithography technology, the pattern of electrode implantation region 2 is fabricated on the surface of the germanium substrate 1. The width of the electrode implantation region 2 is set to 50 μm.

[0068] Step 160: Again, by multiple ion implantation process, boron (B) impurities are implanted into the electrode implantation region 2. The implantation depth of boron is about 3 μm, and the doping concentration is about 1 x 10 19 cm -3 .

[0069] Step 170: By using plasma enhanced chemical vapor deposition (PECVD) technology, a layer of 200 nm thick Si3N4 is deposited on the surface of the germanium substrate 1 as the passivation layer 7 of the device.

[0070] Step 180: Again, by using ultraviolet lithography technology, the electrode pattern is fabricated on the surface of the passivation layer, and then by using wet etching technology, the electrode window is opened on the passivation layer.

[0071] Step 190: By using electron beam evaporation technology, a layer of 20 nm thick palladium (Pd) and a layer of 200 nm thick gold (Au) are sequentially deposited at the electrode window to form the common electrode 6, the first absorption region electrode 8 and the second absorption region electrode 9. Finally, by using rapid annealing technology, the device is annealed at 300 °C for 300 seconds.

[0072] Example 2:

[0073] As shown in the figure, the preparation method of the germanium-based multi-junction type dual-color long-wave infrared detector of the example includes the following steps: Figure 4

[0074] Step 210: A high-resistance germanium substrate 1 is selected, and the doping concentration is set to 1 x 10 13 cm -3 . By using ultraviolet lithography technology, four first monochromatic absorption regions 4 are designed on the surface of the germanium substrate 1, and the width of each absorption region is set to 20 μm, and the width of the barrier region 3 between adjacent two absorption regions is 5 μm. The thickness of the photoresist used in this stage is about 3 μm, which is sufficient as an effective masking layer in the subsequent ion implantation step.

[0075] Step 220: By multiple ion implantation process, boron (B) impurities are implanted into the first monochromatic absorption region 4. The implantation depth of boron is about 1 μm, and the target doping concentration is about 5 x 10 16 cm -3 . ​

[0076] Step 230: Using ultraviolet lithography again, four second monochromatic absorption regions 5 are designed on the surface of the germanium substrate 1. The width of each absorption region is still set to 20 μm, and the width of the blocking region 3 between adjacent absorption regions remains unchanged at 5 μm.

[0077] Step 240: Gallium (Ga) impurities are implanted into the second monochromatic absorption region 5 through multiple ion implantations to a depth of approximately 1 μm, with a target doping concentration of approximately 5 × 10⁻⁶. 16 cm -3 .

[0078] Step 250: Using ultraviolet lithography again, design electrode implantation region 2 on the surface of germanium substrate 1. The width of electrode implantation region 2 is set to 25 μm.

[0079] Step 260: Boron (B) impurities are implanted into electrode implantation region 2 again through multiple ion implantation processes. The implantation depth of boron is approximately 1 μm, and the target doping concentration is approximately 3 × 10⁻⁶. 18 cm -3 .

[0080] Step 270: Using plasma-enhanced chemical vapor deposition (PECVD) technology, a 200 nm thick Si3N4 layer is deposited on the surface of germanium substrate 1 as a passivation layer 7 for the device.

[0081] Step 280: Use ultraviolet lithography to design electrode patterns on the passivation layer again, and then use wet etching process to open electrode windows on the passivation layer.

[0082] Step 290: Using electron beam evaporation, 20 nm thick palladium (Pd) and 200 nm thick gold (Au) are deposited at the electrode windows to form the common electrode 6, the first absorption region electrode 8, and the second absorption region electrode 9. Subsequently, the device is annealed at 300°C for 300 seconds using rapid annealing technology.

[0083] Example 3:

[0084] like Figure 5 As shown, the fabrication method of the germanium-based multi-junction dual-color long-wave infrared detector in this example includes the following steps:

[0085] Step 310: First, select a doping concentration of 1×10⁻⁶. 14 A high-resistivity germanium substrate 1 with a diameter of cm⁻³ was then constructed on the surface of the germanium substrate 1 using ultraviolet lithography. Five first monochromatic absorption regions 4 were then formed on the surface of the germanium substrate 1, each with a width of 5 μm, and a blocking region 3 with a width of 3 μm separating adjacent absorption regions. The photoresist used in this process was approximately 3 μm thick, which would serve as a masking layer in the subsequent ion implantation step.

[0086] Step 320: Boron (B) impurities are implanted into the first single-color absorption region 4 by multiple ion implantation processes, with an implantation depth of about 0.1 μm and a target doping concentration of about 1 x 10 16 cm⁻³. -3 .

[0087] Step 330: Five second single-color absorption regions 5 are constructed on the surface of the germanium substrate 1 by using the ultraviolet lithography technique again, with a width of 5 μm for each absorption region and a width of 3 μm for the barrier region 3 between adjacent absorption regions.

[0088] Step 340: Gallium (Ga) impurities are implanted into the second single-color absorption region 5 by multiple ion implantation processes again, with an implantation depth of about 0.1 μm and a target doping concentration of about 1 x 10 16 cm⁻³. -3 .

[0089] Step 350: An electrode implantation region 2 with a width of 5 μm is constructed on the surface of the germanium substrate 1 by using the ultraviolet lithography technique again.

[0090] Step 360: Boron (B) impurities are implanted into the electrode implantation region 2 by multiple ion implantation processes again, with an implantation depth of about 0.1 μm and a target doping concentration of about 1 x 10 18 cm⁻³.

[0091] Step 370: A 200 nm thick Si3N4 is deposited on the surface of the germanium substrate 1 by using the PECVD technique, as a passivation layer 7 of the device.

[0092] Step 380: An electrode pattern is constructed on the surface of the passivation layer by using the ultraviolet lithography technique again, and then an electrode window is opened on the passivation layer by using a wet etching process.

[0093] Step 390: A 20 nm thick Pd and a 200 nm thick Au are deposited on the electrode window by using the electron beam evaporation technique, to form a common electrode 6, a first absorption region electrode 8 and a second absorption region electrode 9. Finally, a rapid annealing is performed, with an annealing temperature of 300 °C and an annealing time of 300 seconds.

[0094] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Any equivalent changes made on the basis of the structure, shape and principle of the present application should be covered by the protection scope of the present application.

Claims

1. A germanium-based multijunction bicolor long-wave infrared detector, characterized by: The germanium substrate (1) is provided with an electrode injection region (2), a plurality of barrier regions (3), a plurality of first single-color absorption regions (4) and a plurality of second single-color absorption regions (5) on the surface of the germanium substrate (1). The electrode injection region (2), the barrier region (3), the first single-color absorption region (4) and the second single-color absorption region (5) are located in the near surface of the germanium substrate (1). The common electrode (6), the first absorption region electrode (8) and the second absorption region electrode (9) are respectively located on different electrode injection regions. A passivation layer (7) is provided on the plurality of barrier regions (3), the plurality of first single-color absorption regions (4) and the plurality of second single-color absorption regions (5). The plurality of first single-color absorption regions (4) and part of the plurality of barrier regions (3) are located between the common electrode (6) and the plurality of first absorption region electrodes (8) and are periodically distributed. The plurality of second single-color absorption regions (5) and the remaining part of the plurality of barrier regions (3) are located between the common electrode (6) and the plurality of second absorption region electrodes (9) and are periodically distributed. The first single-color absorption region (4) and the second single-color absorption region (5) are both degenerate doped germanium materials, and the doping impurity types of the first single-color absorption region (4) and the second single-color absorption region (5) are different. The electrode injection region (2), the barrier region (3), the first single-color absorption region (4) and the second single-color absorption region (5) are located in the near surface of the germanium substrate (1), and the depth on the surface of the germanium substrate (1) is 0.1-3 μm.

2. The Ge-based multijunction bicolor LWIR detector of claim 1, wherein: The ratio of the number of the first single-color absorption region (4), the second single-color absorption region (5) and the barrier region (3) is 1:1:

2.

3. The Ge-based multijunction bicolor LWIR detector of claim 1, wherein: The number of the first single-color absorption region (4) + the number of the second single-color absorption region (5) = the number of the barrier region (3).

4. The Ge-based multijunction bicolor LWIR detector of claim 1, wherein: The result of (the number of the first single-color absorption region (4) × the width of the first single-color absorption region (4)) + (the number of the second single-color absorption region (5) × the width of the second single-color absorption region (5)) is a constant value.

6. The germanium-based multi-junction dual-color long-wave infrared detector according to claim 1, characterized in that:

5. The Ge-based multijunction bicolor LWIR detector of claim 1, wherein: The germanium substrate (1) is a high resistance type germanium substrate having an impurity concentration ranging from 1 x 10 12 to 1 x 10 14 cm -3 -1. The method for preparing the germanium-based multi-junction dual-color long-wave infrared detector according to any one of claims 1-7 comprises the following steps: The doping element of the first single-color absorption region (4) is one or more of boron, gallium, beryllium, phosphorus or sulfur, the impurity concentration ranges from 1×10 16 to 1×10 17 cm -3 , the doping depth ranges from 0.1 μm to 3 μm, and the width ranges from 5 μm to 50 μm, The doping element of the second single-color absorption region (5) is one or more of boron, gallium, beryllium, phosphorus or sulfur, the impurity concentration ranges from 1x10 16 to 1x10 17 cm -3 , the doping depth ranges from 0.1 μm to 3 μm, and the width ranges from 5 μm to 50 μm.

7. The Ge-based multijunction bicolor LWIR detector of claim 1, wherein: The electrode implant region (2) is a degenerately doped germanium material doped with one or more impurities of boron, gallium, beryllium, or phosphorus at a concentration of 1 x 1018 18 to 1 x 1020 19 cm -3 with a doping depth of 0.1 μm to 3 μm and a width of 5 μm to 50 μm.

8. A method for fabricating a Ge-based multijunction bicolor long-wave infrared detector, the method comprising: A plurality of first single-color absorption regions (4) are formed on the surface of the germanium substrate (1) by using ultraviolet lithography technology and using photoresist as a masking layer, and then a plurality of first single-color absorption regions (4) are formed by injecting impurities into the first single-color absorption regions (4) using an ion implantation process. ​ A plurality of second single-color absorption regions (5) are formed on the surface of the germanium substrate (1) by using ultraviolet lithography technology, and then a plurality of second single-color absorption regions (5) are formed by injecting impurities into the second single-color absorption regions (5) using an ion implantation process. ​ The pattern of the electrode injection region (2) is formed on the surface of the germanium substrate (1) by using ultraviolet lithography technology, and then the electrode injection region (2) is formed by injecting impurities into the pattern by using ion implantation process; The passivation layer (7) is deposited on the surface of the germanium substrate (1) by using plasma enhanced chemical vapor deposition process, and then heat treatment is performed to activate the injected impurities; The electrode holes are made on the passivation layer (7) by using wet etching process, and then the common electrode (6), the plurality of first absorption region electrodes (8) and the plurality of second absorption region electrodes (9) are formed by using metal deposition process.

9. The method of claim 8, wherein the Ge-based multijunction bicolor LWIR detector is prepared by the steps of: The doping concentration of the germanium substrate is 1×10 12 cm -3 -3; the number of the first single-color absorption regions is 2, the width is 50μm, and the interval between adjacent first single-color absorption regions is 10μm; the first single-color absorption regions are doped with gallium, the doping depth is 3μm, and the doping concentration is 1×10 17 cm -3 -3; the number of the second single-color absorption regions is 2, the width is 50μm, and the interval between adjacent second single-color absorption regions is 10μm; the second single-color absorption regions are doped with gallium, the doping depth is 3μm, and the doping concentration is 1×10 -3 cm 19 -3; the width of the electrode injection region is 50μm, the electrode injection region is doped with boron, the doping depth is 3μm, and the doping concentration is 1×10 -3 cm -3. ​ 10. The method of claim 8, wherein the Ge-based multijunction bicolor LWIR detector is prepared by the steps of: The doping concentration of the germanium substrate is 1×10 13 cm -3 -3; the number of the first single-color absorption regions is 4, the width is 20μm, and the interval between adjacent first single-color absorption regions is 5μm; the first single-color absorption regions are doped with gallium, the doping depth is 0.5μm, and the doping concentration is 5×10 16 cm -3 -3; the number of the second single-color absorption regions is 4, the width is 20μm, and the interval between adjacent second single-color absorption regions is 5μm; the second single-color absorption regions are doped with boron, the doping depth is 1μm, and the doping concentration is 5×10 16 cm -3 -3; the width of the electrode injection region is 25μm, the electrode injection region is doped with boron, the doping depth is 1μm, and the doping concentration is 3×10 18 cm -3 -3. ​ 11. The method of claim 8, wherein the Ge-based multijunction bicolor LWIR detector is prepared by the steps of: The doping concentration of the germanium substrate is 1×10 14 cm -3 -3; the number of the first monochromatic absorption region is 5, the width is 5μm, and the interval between adjacent first monochromatic absorption regions is 3μm; boron is injected into the first monochromatic absorption region, the doping depth is 0.1μm, and the doping concentration is 1×10 16 cm -3 -3; the number of the second monochromatic absorption region is 5, the width is 5μm, and the interval between adjacent second monochromatic absorption regions is 3μm; gallium is injected into the second monochromatic absorption region, the doping depth is 0.1μm, and the doping concentration is 1×10 16 cm -3 -3; the width of the electrode injection region is 5μm, boron is doped therein, the doping depth is 0.1μm, and the doping concentration is 1×10 18 cm -3 -3. ​

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