A wavelength detector based on two photodetector units

Abstract

The application discloses a wavelength detector based on two photoelectric detection units, which comprises two photoelectric detection units with semiconductor wafers or perovskite thin films as light absorption layers and arranged in parallel in up-down or front-back directions. When light irradiates the wavelength detector from the photoelectric detection unit located above or in front and goes down or backward layer by layer, the current ratio of the two photoelectric detection units regularly changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio. The wavelength detector has the advantages of stable property, high reliability, fast response speed, high accuracy and repeatability, and simple preparation process and low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectric detection, and particularly relates to a wavelength detector. BACKGROUND

[0002] Wavelength sensors, as an important part of modern optoelectronic technology, have a wide range of applications in medical diagnosis, visible light communication (VLC), non-destructive analysis technology and spectrometer, etc. In addition, high-precision wavelength sensors are also an important part of spectrometers, because they can reconstruct monochromatic and polychromatic spectra in the visible range, which is crucial for in-situ characterization technology. So far, people have been committed to developing wavelength detectors of various different mechanisms. The most direct wavelength detector is usually composed of different kinds of photodetectors, the purpose of which is to sense the target wavelength, sometimes with the assistance of some optical filters. In addition, integrating shallow and deep p-n junctions on silicon is also a reliable strategy to achieve spectral detection. Generally, the shallow p-n junctions are located at 0.3 and 0.9 microns below the surface, which are used to distinguish blue light (about 450 nm) and green light (about 570 nm), respectively, while the deep p-n junction is located at 4 microns, which is used to detect red light (about 740 nm). Recently, a new type of filter-free wavelength-sensitive photodetector has also been proposed, which can detect different wavelengths in the visible range according to the continuous adjustable band gap of perovskite materials, and the entire visible spectral resolution of the wavelength detector is about 80 nm without adding any auxiliary materials.

[0003] Under such a background, there are some problems to be solved urgently: (1) The detection range of the wavelength detector with filter-assisted technology is relatively narrow, generally in the visible light band. (2) The structures of most of the above wavelength detection devices are relatively complex, and the preparation cost is relatively high. (3) The detection efficiency is relatively low, and the detection speed and accuracy need to be improved. (4) The resolution of the wavelength detector is an extremely important performance parameter, but the resolution of the current wavelength detector is about tens of nanometers, which cannot meet the needs of some applications. Therefore, it is crucial to develop high-resolution ultraviolet-infrared wavelength detectors. SUMMARY

[0004] In order to avoid the deficiencies existing in the prior art, the purpose of the present application is to provide a wavelength detector based on two photodetectors, which has high detection speed and accuracy, high resolution, wide wavelength detection range, simple preparation process and low cost.

[0005] In order to achieve the purpose, the application adopts the following technical scheme:

[0006] A wavelength detector based on two photodetector units, characterized in that the wavelength detector comprises two photodetector units arranged in parallel in an up-down or front-back manner; the photodetector unit is a heterojunction type, photoconductive type or Schottky junction type photodetector unit with a semiconductor wafer or perovskite film as an absorbing layer;

[0007] When light irradiates the wavelength detector layer by layer from the photodetector unit located above or in front, the current ratio of the two photodetector units changes regularly with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio. The regular change can be gradual increase or gradual decrease.

[0008] Further, when the photodetector unit is of the photoconductive type, the structure is that a semiconductor wafer or perovskite film is provided with a metal counter electrode in ohmic contact therewith;

[0009] Further, when the photodetector unit is of the heterojunction type, the structure is that a semiconductor wafer or perovskite film is provided with a metal material or two-dimensional film material forming a heterojunction therewith;

[0010] Further, when the photodetector unit is of the Schottky junction type, the structure is that a semiconductor wafer or perovskite film is provided with a metal material or two-dimensional film material forming a Schottky junction therewith.

[0011] Further, the material of the semiconductor wafer is silicon, germanium, III-V semiconductor material or II-V semiconductor material. The III-V semiconductor material is indium arsenide (InAs), gallium arsenide (CaAs) or indium phosphide (InP); the II-V semiconductor material is mercury cadmium telluride (HgCdTe).

[0012] Further, the perovskite film is FA 0.85 Cs 0.15 PbI3 perovskite film or CsBi3I 10 perovskite film.

[0013] Further, the two-dimensional film material is graphene, palladium diselenide, palladium telluride, platinum diselenide or platinum telluride.

[0014] Based on the above wavelength detector, the present application specifically proposes the following four structures:

[0015] Structure one:

[0016] The wavelength detector comprises two identical photodetector units arranged in parallel in an up-down or front-back manner;

[0017] The photoelectric detection unit is structured as follows: a FA 0.85 Cs 0.15 PbI3 perovskite film, a pair of gold electrodes is arranged on the perovskite film;

[0018] When light irradiates the wavelength detector from the photoelectric detection unit located above or in front layer by layer downward or backward, the current ratio of the two photoelectric detection units regularly changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the detectable wavelength range includes 265-970nm.

[0019] Structure two:

[0020] The wavelength detector comprises two identical photoelectric detection units arranged in parallel in up-down or front-back direction;

[0021] The photoelectric detection unit is structured as follows: a germanium sheet; an insulating layer is deposited on part of the upper surface of the germanium sheet, and an indium-gallium alloy electrode is arranged on the lower surface of the germanium sheet; a graphene film is transferred on the insulating layer, part of the graphene film is on the insulating layer, and the rest of the graphene film is in contact with the germanium sheet without the insulating layer and forms a Schottky junction; a metal electrode in ohmic contact with the graphene is arranged on the graphene film, the metal electrode is directly above the insulating layer and does not exceed the area of the insulating layer; the germanium sheet is fixed on a glass substrate;

[0022] When light irradiates the wavelength detector from the photoelectric detection unit located above or in front layer by layer downward or backward, the current ratio of the two photoelectric detection units regularly changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the detectable wavelength range includes 530-1650nm.

[0023] Structure three:

[0024] The wavelength detector comprises a first photoelectric detection unit and a second photoelectric detection unit arranged in parallel in up-down or front-back direction;

[0025] The first photoelectric detection unit is structured as follows: an ultrathin silicon sheet fixed on a glass substrate; a graphene interdigital electrode is arranged on the ultrathin silicon sheet, and a Schottky junction is formed by graphene and ultrathin silicon;

[0026] The second photoelectric detection unit comprises a germanium sheet, an insulating layer deposited on a part of the upper surface of the germanium sheet, an indium-gallium alloy electrode arranged on the lower surface of the germanium sheet, a graphene film transferred on the insulating layer, a part of the graphene film being on the insulating layer and the rest of the graphene film being in contact with the germanium sheet without the insulating layer and forming a Schottky junction, a metal electrode in ohmic contact with the graphene and arranged on the graphene film and located directly above the insulating layer and not exceeding the area of the insulating layer, and the germanium sheet being fixed on a glass substrate.

[0027] When light irradiates the wavelength detector from the first photoelectric detection unit layer by layer downwards or backwards, the current ratio of the two photoelectric detection units gradually changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the wavelength range that can be detected includes 265-1550 nm.

[0028] Structure four:

[0029] The wavelength detector is provided with a 30-100 nm thick metal interdigital electrode or a pair of 0.34-30 nm thick two-dimensional thin film material electrodes forming a Schottky junction, a heterojunction or an ohmic contact on the upper and lower surfaces of a semiconductor wafer, and the semiconductor wafer and the electrodes on the two sides form two photoelectric detection units.

[0030] When light irradiates the wavelength detector from the upper surface of the semiconductor wafer layer by layer backwards, the current ratio of the two photoelectric detection units gradually changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the wavelength range that can be detected includes 265-2000 nm.

[0031] Compared with the prior art, the beneficial effects of the present application are embodied in:

[0032] 1. The wavelength detector is designed based on two photoelectric detection units, and the wavelength detector is composed of two photoelectric detection units with the same structure or different structures. The selected light-absorbing materials of the wavelength detector are thin silicon sheets, germanium sheets, III-V or II-V semiconductor wafers, perovskite thin film materials, etc. According to the different light-absorbing materials, the wavelength range that can be detected includes 265-1660 nm, which covers the ultraviolet to mid-infrared band.

[0033] 2. The wavelength detector has the advantages of stable properties, high reliability, fast response speed, high accuracy and high repeatability, and the preparation process is simple and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1-1 The wavelength detector based on FA 0.85 Cs 0.15The wavelength detector of the PbI3 perovskite film structure diagram, the figure mark: 1-1 is gold electrode, 1-2 is FA 0.85 Cs 0.15 PbI3 perovskite film, 1-3 is quartz substrate.

[0035] Figure 1-2 And Figure 1-3 The wavelength detector obtained by the embodiment 1 of the application under the detection condition of temperature 300K, 0V bias, the photoelectric current-wavelength characteristic curve of the upper photoelectric detection unit (1-1) and the lower photoelectric detection unit (1-2) under the illumination of wavelength 265-970nm, intensity from 100 to 500μW / cm 2 . Figure 1-2 Figure 1-3

[0036] Figure 1-4 The wavelength detector obtained by the embodiment 1 of the application under the detection condition of temperature 300K, 0V bias, the photoelectric current ratio (I ph1 / I ph2 )-wavelength curve contrast diagram of the upper photoelectric detection unit and the lower photoelectric detection unit under the illumination of wavelength 265-970nm, intensity from 100 to 500μW / cm 2 .

[0037] Figure 2-1 The structure diagram of the wavelength detector based on graphene / germanium schottky junction obtained by the embodiment 2 of the application, the figure mark: 2-1 is metal electrode; 2-2 is graphene film; 2-3 is insulating layer; 2-4 is germanium sheet; 2-5 is indium gallium alloy electrode; 2-6 is glass substrate.

[0038] Figure 2-2 And Figure 2-3 The wavelength detector obtained by the embodiment 2 of the application under the detection condition of temperature 300K, 0V bias, the photoelectric current-wavelength characteristic curve of the upper photoelectric detection unit (2-1) and the lower photoelectric detection unit (2-2) under the illumination of wavelength 530-1660nm, intensity from 800 to 1300μW / cm 2 . Figure 2-2 Figure 2-3

[0039] Figure 2-4 The wavelength detector obtained by the embodiment 2 of the application under the detection condition of temperature 300K, 0V bias, the photoelectric current ratio (I ph1 / I ph2 )-wavelength curve of the upper photoelectric detection unit and the lower photoelectric detection unit under the illumination of wavelength 530-1660nm, intensity from 800 to 1300μW / cm 2 .

[0040] ​​​​Figure 3-1 Structure diagram of wavelength detector obtained in Example 3 of the present application;

[0041] Figure 3-2 and Figure 3-3 are photoelectric current-wavelength characteristic curves of the upper photoelectric detection unit and the lower photoelectric detection unit, respectively, of the wavelength detector obtained in Example 3 of the present application under the detection conditions of temperature 300 K, 0.5-3 V bias voltage, and illumination of wavelength 265-1550 nm and intensity 1200 μW / cm 2 Figure 3-2 Figure 3-3

[0042] Figure 3-4 are photoelectric current-wavelength characteristic curves of the upper photoelectric detection unit and the lower photoelectric detection unit, respectively, of the wavelength detector obtained in Example 3 of the present application under the detection conditions of temperature 300 K, 0.5-3 V bias voltage, and illumination of wavelength 265-1550 nm and intensity 1200 μW / cm 2 ph1 ph2

[0043] Figure 3-5 are photoelectric current-wavelength characteristic curves of the upper photoelectric detection unit and the lower photoelectric detection unit, respectively, of the wavelength detector obtained in Example 3 of the present application under the detection conditions of temperature 300 K, 2 V bias voltage, and illumination of wavelength 265-1550 nm and intensity from 200 to 1200 μW / cm 2

[0044] Figure 3-6 are photoelectric current-wavelength characteristic curves of the upper photoelectric detection unit and the lower photoelectric detection unit, respectively, of the wavelength detector obtained in Example 3 of the present application under the detection conditions of temperature 300 K, 0 V bias voltage, and illumination of wavelength 265-1550 nm and intensity 200-1200 μW / cm 2

[0045] Figure 3-7 are photoelectric current-wavelength characteristic curves of the upper photoelectric detection unit and the lower photoelectric detection unit, respectively, of the wavelength detector obtained in Example 3 of the present application under the detection conditions of temperature 300 K, 2 V bias voltage for the upper photoelectric detection unit and 0 V bias voltage for the lower photoelectric detection unit, and illumination of wavelength 265-1550 nm and intensity 1200 μW / cm 2 ph1 ph2

[0046] Figure 4-1 ​​​​​​​​​​​This is a schematic diagram of the wavelength detector based on the Si / Au Schottky junction obtained in Embodiment 4 of the present invention. In the figure, the numbers are: 4-1 gold interdigitated electrode; 4-2 silver paste; 4-3 silicon wafer.

[0047] Figure 4-2 The wavelength detector obtained in Example 4 of this invention has a wavelength range of 265–700 nm and an intensity range of 800–1300 μW / cm. 2 Under internal 1V bias voltage, the photocurrent ratio I between the detection wavelength and the wavelength detection unit is... ph1 / I ph2 Working curve graph.

[0048] Figure 4-3 This refers to the error of the wavelength detector obtained in Embodiment 4 of the present invention within the wavelength range of 265 to 700 nm and under each 5 nm wavelength illumination. Detailed Implementation

[0049] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to examples. The following content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not depart from the inventive concept or exceed the scope defined by the claims, all of which should fall within the protection scope of the present invention.

[0050] Example 1

[0051] like Figure 1-1 As shown, this embodiment is based on FA. 0.85 Cs 0.15 A wavelength detector with a detection range in the ultraviolet-visible spectrum was designed using a PbI3 perovskite thin film, which is composed of two identical photoconductive photodetector units.

[0052] The structure of the two photoconductive photodetector units is as follows: A FA with a thickness of approximately 350 nm was prepared on the upper surface of a quartz substrate 1-3 with a thickness of 1 mm using a simple one-step spin-coating method. 0.85 Cs 0.15 PbI3 perovskite thin films 1-2, in FA 0.85 Cs 0.15 A gold electrode 1-1 with a thickness of approximately 50 nm was deposited on the PbI3 perovskite thin film 1-2 using an electron beam evaporator. (Factory name omitted) 0.85 Cs 0.15 The PbI3 perovskite thin film forms an ohmic contact with the gold electrode, creating a photoconductive photodetector unit.

[0053] The lower surface of the quartz substrate of the first photoconductive photodetecting unit is overlapped with the upper surface of the quartz substrate of the second photoconductive photodetecting unit, that is, a wavelength detector is formed. Figure 1-1 In order to clearly show the structure of the two photoconductive photodetecting units, the two units are split and not overlapped. In actual use, the two units can be bonded or bundled, as long as the positions of the two units are fixed.

[0054] The wavelength detector of the embodiment is prepared by the following steps:

[0055] Step 1: A quartz substrate with an area of 1 cm x 1 cm and a thickness of 1 mm is sequentially ultrasonically cleaned with acetone, alcohol and deionized water for 10 minutes, and dried with nitrogen.

[0056] Step 2: The quartz substrate treated in step 1 is exposed to O2 plasma for 10 min.

[0057] Step 3: In a 5 mL reagent bottle, 461 mg of PbI2 (Macklin, 99%), 38.9 mg of CsI (Macklin, 99.9%) and 146 mg of FAI (Aldrich, 99.5%) are sequentially dissolved in a mixed solvent of 900 μL of N,N-dimethylformamide (DMF, 99.8%) and 100 μL of dimethyl sulfoxide (DMSO, 99.9%), stirred at 60°C for 2 h, to obtain a FA 0.85 Cs 0.15 PbI3 perovskite precursor solution.

[0058] Step 4: The FA 0.85 Cs 0.15 PbI3 perovskite precursor solution obtained in step 3 is spin-coated on the surface of the quartz substrate treated in step 2. The spin-coating process is divided into two steps: first, a slow rotation speed of 600 rpm is maintained for 10 s, and then a fast rotation speed of 4000 rpm is maintained for 30 s. After 20 s of spin-coating, 300 μL of ethyl acetate solution (99.0%) is dropped onto the perovskite film. After spin-coating the film for 40 s, the substrate is heated on a heating stage at 135°C for 10 min, and finally a black-brown FA 0.85 Cs 0.15 PbI3 perovskite thin film.

[0059] Step 5: With the help of a shadow mask, an Au electrode with a thickness of about 50 nm is deposited by an electron beam evaporator. The channel length L is 2 mm and the width W is 9 μm, that is, a photoconductive photodetecting unit is formed.

[0060] Step 6: Take two identical photoconductive photodetector units prepared according to steps 1-5, and stack the lower surface of the quartz substrate of the first photoconductive photodetector unit with the upper surface of the quartz substrate of the second photoconductive photodetector unit to obtain a FA-based... 0.85 Cs 0.15 Wavelength detectors for PbI3 perovskite thin films.

[0061] Figure 1-2 and Figure 1-3 The wavelength detectors obtained in this embodiment are respectively located at wavelengths of 265-970 nm and intensities of 100-500 μW / cm. 2 Under light (such as) Figure 1-1 As shown, to match the direction of the light (the wavelength detector was erected during the test), the current-wavelength characteristic curves of the first and second photoconductive photodetector units are displayed under detection conditions of room temperature and zero operating voltage. It can be seen from the figure that due to the FA... 0.85 Cs 0.15 The relationship between the absorption coefficient and wavelength of PbI3 perovskite thin films shows that two identical photoconductive detectors exhibit different spectral responses. Figure 1-4 The figure shows the current-wavelength characteristic curves of the first and second photoconductive photodetectors under these conditions. It can be seen from the figure that, under the same light intensity, when the wavelength is 265-970nm, the photocurrent ratio decreases monotonically with increasing wavelength, and the light intensity ratio is somewhat affected before 530nm. Therefore, it can be concluded that the wavelength detector in this embodiment can detect wavelengths ranging from 265-970nm and can complete detection under specific light intensities.

[0062] Example 2

[0063] like Figure 2-1 As shown, this embodiment utilizes two identical photodetector units based on graphene / germanium Schottky junctions to construct a wavelength detector, which can detect light from the visible to the infrared spectrum and can operate under any light intensity.

[0064] The structure of the two photoelectric detection units is as follows: a germanium sheet 2-4 is fixed on the upper surface of the glass substrate 2-6; an insulating layer 2-3 is deposited on a portion of the upper surface of the germanium sheet, and an indium gallium alloy electrode 2-5 is disposed on the lower surface of the germanium sheet; a graphene film 2-2 is transferred on the insulating layer, a portion of the graphene film is located on the insulating layer, and the remaining portion contacts the germanium sheet without an insulating layer and forms a Schottky junction; a metal electrode 2-1 is disposed on the graphene film in ohmic contact with the graphene, and the metal electrode is located directly above the insulating layer and does not extend beyond the area of ​​the insulating layer.

[0065] The lower surface of the glass substrate of the first photodetecting unit is overlapped with the upper surface of the glass substrate of the second photodetecting unit, that is, a wavelength detector is formed. Figure 2-1 In order to clearly show the structure of the two Schottky junction units, the two units are split and not overlapped. In actual use, the two units can be bonded or bundled, as long as the positions of the two units are fixed.

[0066] Specifically, in the embodiment, the thickness of the glass substrate 2-6 is 1 mm; the thickness of the germanium sheet is 200 μm; the thickness of the single-layer graphene 2-2 is about 0.35 nm; the insulating layer is Al2O3, and the thickness is about 300 nm; and the metal electrode is a gold electrode with a thickness of 50 nm.

[0067] The wavelength detector of the embodiment is prepared by the following steps.

[0068] Step 1: A glass substrate with an area of 1 cm x 1 cm and a thickness of 1 mm and a germanium sheet with an insulating layer with a thickness of about 300 nm, an area of 0.6 cm x 0.8 cm and a thickness of 200 μm are sequentially ultrasonically cleaned with acetone, alcohol and deionized water for 10 minutes, and dried with nitrogen.

[0069] Step 2: The germanium sheet treated in step 1 is spin-coated with a positive photoresist, and the spin-coating process is as follows: first, a slow rotation speed of 600 rpm is maintained for 10 s, then a fast rotation speed of 3000 rpm is maintained for 30 s, and finally, the sample is heated on a heating table at 100 ℃ for 5 min. The sample is exposed to ultraviolet light for 12.1 s under a mask with a window area of 1.8 mm x 2.0 mm, and developed for 25 s.

[0070] Step 3: The germanium sheet treated in step 2 is placed in a dilute hydrochloric acid etching solution with a specific ratio of HCl:H2O = 1:2, and etched at room temperature for 8 h. The insulating layer in the window is etched away, and the germanium is exposed, that is, a germanium window is formed.

[0071] Step 4: After the lower surface of the germanium sheet treated in step 3 is coated with an indium-gallium alloy electrode, the germanium sheet is fixed on the glass substrate treated in step 1.

[0072] Step 5: The single-layer graphene prepared is transferred to the germanium sheet with a window treated in step 4 by using a wet transfer technique, and is allowed to stand for 24 h, and heated on a heating table at 100 ℃ for 5 min.

[0073] Step 6: With the help of a shadow mask, a gold electrode with a thickness of about 50 nm is deposited on the germanium sheet treated in step 5 by using an electron beam evaporator. The gold electrode is located directly above the insulating layer and does not exceed the area of the insulating layer.

[0074] Step 7, take two same photoelectric detection units prepared according to steps 1-6, and superpose the lower surface of the glass substrate of the first photoelectric detection unit with the upper surface of the glass substrate of the second photoelectric detection unit, to obtain a wavelength detector.

[0075] Figure 2-2 and Figure 2-3 are photoelectric currents of the wavelength detector obtained in the present embodiment under illumination of light with wavelength of 530-1650 nm, working bias of 0 V for the first photoelectric detection unit and the second photoelectric detection unit, and illumination intensity from 800-1300 μW / cm 2 It can be seen that due to different transmission depths of light with different wavelengths in the germanium sheet, the two photoelectric detection units exhibit different spectral responses. It can be seen from Figure 2-4 that at room temperature, the current ratio of the photoelectric current of the first photoelectric detection unit ( Figure 2-2 ) and the photoelectric current of the second photoelectric detection unit ( Figure 2-3 ) under different light intensities has a monotonic relationship with the wavelength in the wavelength range of 530-1650 nm. This means that when monochromatic light with an unknown wavelength is incident on the wavelength detector, the wavelength can be determined by the known photoelectric current ratio. Moreover, under different light intensities, the characteristic curve of the wavelength and the photoelectric current ratio is basically unchanged, and it can be concluded that the wavelength detector of the present embodiment can detect the wavelength without being affected by the light intensity, and the detection range is from visible light to infrared.

[0076] Example 3

[0077] As shown in Figure 3-1 , the present embodiment superposes a graphene / ultra-thin silicon-based photoelectric detection unit (as the first photoelectric detection unit) and a graphene / germanium-based photoelectric detection unit (as the second photoelectric detection unit) to form a wavelength detector, and the detection range thereof is from ultraviolet to infrared spectrum.

[0078] The structure of the graphene / ultra-thin silicon-based photoelectric detection unit is as follows: a piece of ultra-thin silicon sheet 3-2 with a thickness of about 20 μm is fixed on the upper surface of the glass substrate 3-3, a layer of graphene film 3-1 is transferred on the ultra-thin silicon 3-2 by using a wet transfer method, then a pattern of interdigital electrodes is photoetched by using ultraviolet exposure, and the graphene interdigital electrodes are etched by using ICP; the graphene and the ultra-thin silicon form a Schottky junction.

[0079] The structure of the graphene / germanium-based photodetector unit is the same as in Example 2: a 200 μm thick germanium sheet 3-6 is fixed on the upper surface of the glass substrate 3-3; an insulating layer 3-5 is deposited on a portion of the upper surface of the germanium sheet, and an indium gallium alloy electrode 3-7 is disposed on the lower surface of the germanium sheet; a graphene film 3-1 is transferred onto the insulating layer, a portion of the graphene film is located on the insulating layer, and the remaining portion contacts the germanium sheet without an insulating layer and forms a Schottky junction; a 50 nm thick gold electrode 3-4 is disposed on the graphene film, which is in ohmic contact with the graphene, and the gold electrode is located directly above the insulating layer and does not extend beyond the region of the insulating layer.

[0080] A wavelength detector is formed by stacking the lower surface of the glass substrate of the first photodetector unit with the upper surface of the glass substrate of the second photodetector unit. Figure 3-1 In order to clearly show the structure of the two Schottky junction units, they are separated and not superimposed. In actual use, they can be glued or tied together, as long as their positions are fixed.

[0081] Specifically, in this embodiment: the thickness of the glass substrate is 1 mm; the thickness of the graphene film is approximately 0.35 nm; and the insulating layer is Al2O3 with a thickness of approximately 300 nm.

[0082] Figure 3-2 and Figure 3-3 The first and second photodetector units in the wavelength detector obtained in this embodiment are respectively located at wavelengths of 265–1550 nm and intensity of 1200 μW / cm. 2 Photocurrent under illumination (e.g.) Figure 3-1 As shown, the color detector was positioned vertically during the test to match the direction of the light. Under room temperature conditions, the photocurrent of the first photodetector unit was measured at operating bias voltages of 0.5-3V. Figure 3-2 The second photoelectric detection unit, due to its unique structure, exhibits a photovoltaic effect, thus allowing the measurement of photocurrent under zero operating voltage conditions. Figure 3-3 The photocurrent (I) of the first photodetector unit under different operating voltages. Ph1 ) and the photocurrent (I) of the second photodetector unit under 0V bias voltage Ph2 The ratio is monotonically related to the wavelength, and the operating curve remains essentially consistent after 2V. From Figure 3-4 It can be seen that when the wavelength is 265-1550nm, the photocurrent ratio decreases monotonically with increasing wavelength. Therefore, the color detector in this embodiment can detect colors ranging from 265-1550nm and is more suitable for operation under a 2V bias voltage.

[0083] Figure 3-5 and Figure 3-6are the photocurrent-wavelength curves of the wavelength detector obtained in this embodiment under the illumination of light with wavelengths of 265-1550 nm and illumination intensities of 200 μW / cm 2 , 500 μW / cm 2 , 800 μW / cm 2 , 1000 μW / cm 2 , and 1200 μW / cm 2 , respectively, wherein the first photoelectric detection unit adopts a working bias of 2 V and the second photoelectric detection unit adopts a working bias of 0 V. The current ratio of the photocurrent ( Figure 3-5 ) of the first photoelectric detection unit and the photocurrent ( Figure 3-6 ) of the second photoelectric detection unit has a monotonic relationship with the wavelength under different light intensities at room temperature. It can be seen from Figure 3-7 that the ratio of the photocurrents of the wavelengths of 265-660 nm is affected to a certain extent as the light intensity increases, and it can be concluded that the wavelength detector of this embodiment can detect wavelengths in the range of 265-1550 nm under a specific light intensity.

[0084] Embodiment 4

[0085] As shown in Figure 4-1 , the wavelength detector of this embodiment based on a Si / Au Schottky junction is provided with gold interdigital electrodes 4-1 on the upper and lower surfaces of a silicon wafer 4-3, and the silicon wafer and the interdigital electrodes on the two sides form two photoelectric detection units; silver paste 4-2 is used to connect silver wires on the gold interdigital electrodes 4-1 for testing. The two photoelectric detection units are symmetrically distributed on the two sides of the silicon.

[0086] Specifically, in this embodiment: the silicon wafer 4-3 is an n-type lightly doped silicon wafer with a thickness of 200 μm and a resistivity of about 2 Ω / cm; the thickness of the gold interdigital electrodes 4-1 is 50 nm; and the thickness of the silver paste 4-2 is 300 nm.

[0087] The wavelength detector of this embodiment is prepared by the following steps:

[0088] Step 1: A silicon wafer with an area of 1 cm×0.5 cm and a thickness of 200 μm is sequentially cleaned with acetone, alcohol, and deionized water for 10 minutes each, and then dried with nitrogen.

[0089] Step 2: The silicon wafer treated in Step 1 is spin-coated with positive photoresist, and the spin-coating process is as follows: first, a slow speed of 600 rpm is maintained for 10 s, then a fast speed of 3000 rpm is maintained for 30 s, and finally, heating is performed on a heating table at 100°C for 5 min. Under a mask plate with an interpolation electrode area of 1 cm×0.5 cm, ultraviolet light is exposed for 12.1 s, and developed for 15 s, and the interpolation electrode has a spacing of 200 μm and a width of 200 μm.

[0090] Step 3, the silicon wafer treated in step 2 is deposited with gold electrode with thickness of about 50nm by electron beam evaporator;

[0091] Step 4, one side of the silicon wafer treated in step 3 is spin-coated with PMMA to protect the gold intercalation electrode. During the spin-coating process, the rotation speed is 4000rpm, and the duration is 30s, and the wafer is heated on the heating table at 80℃ for 5min.

[0092] Step 5, the silicon wafer treated in step 4 is repeated with step 2 and step 3 to prepare an intercalation electrode on the other side of the silicon, which is symmetrical to the previous intercalation electrode.

[0093] The wavelength detector is obtained after step 1-5.

[0094] Figure 4-2 The wavelength detector obtained in the present embodiment is tested under the conditions that the wavelength is 265-1050nm, the first photodetecting unit and the second photodetecting unit are operated at 1V bias, and the light intensity is from 800-1300μW / cm 2 The working curve under random variation and the photocurrent ratio tested every 5nm within the wavelength of 265-1050nm are shown in the following table. It can be seen that the photocurrent ratio of the first photodetecting unit I Ph1 and the photocurrent of the second photodetecting unit I Ph2 has a monotonic relationship with the wavelength, and the test data is basically consistent with the working curve. Figure 4-3 To analyze the accuracy of the wavelength detection of the wavelength detector in the present embodiment, the photocurrent ratio is tested again every 5nm within the wavelength of 265-1050nm under the same detection conditions, and compared with the photocurrent ratio of the corresponding wavelength in the working curve in Figure 4-2 Figure 4-2 The error is calculated as follows: Δλ=(λ)1-(λ)0. The result shows that the error range is-4.90-4.81nm every 5nm within the wavelength of 265-1050nm. It can be seen that the wavelength detector in the present embodiment has very high precision and repeatability within the wavelength of 265-1050nm.

[0095] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can make equivalent substitution or change according to the technical solution and the inventive concept of the present application within the technical range disclosed in the present application, which should be covered in the protection scope of the present application.​

Claims

1. A wavelength detector based on two photodetector units, characterized in that: The wavelength detector comprises two identical photodetecting units arranged in parallel in up-down or front-back direction; the photodetecting unit is structured as follows: a FA 0.85 Cs 0.15 PbI3 perovskite film, and a pair of gold electrodes arranged on the perovskite film; when light irradiates the wavelength detector from the photodetecting unit located above or in front and irradiates layer by layer downwards or backwards, the current ratio of the two photodetecting units changes regularly with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the wavelength range that can be detected includes 265-970 nm. Alternatively, the wavelength detector comprises two identical photodetecting units stacked in parallel from top to bottom or from front to back; the photodetecting unit comprises a germanium sheet; an insulating layer is deposited on part of the upper surface of the germanium sheet, and an indium-gallium alloy electrode is arranged on the lower surface of the germanium sheet; a graphene film is transferred on the insulating layer, part of the graphene film is on the insulating layer, and the rest of the graphene film is in contact with the germanium sheet without the insulating layer and forms a Schottky junction; a metal electrode in ohmic contact with the graphene is arranged on the graphene film, the metal electrode is directly above the insulating layer and does not exceed the area of the insulating layer; the germanium sheet is fixed on a glass substrate; when light irradiates the wavelength detector from the photodetecting unit above or in front layer by layer downwards or backwards, the current ratio of the two photodetecting units changes regularly with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the detectable wavelength range includes 530-1650 nm; Alternatively, the wavelength detector comprises a first photodetecting unit and a second photodetecting unit stacked in parallel from top to bottom or from front to back; the first photodetecting unit comprises an ultrathin silicon sheet fixed on a glass substrate; a graphene interdigital electrode is arranged on the ultrathin silicon sheet, and a Schottky junction is formed by the graphene and the ultrathin silicon; the second photodetecting unit comprises a germanium sheet; an insulating layer is deposited on part of the upper surface of the germanium sheet, and an indium-gallium alloy electrode is arranged on the lower surface of the germanium sheet; a graphene film is transferred on the insulating layer, part of the graphene film is on the insulating layer, and the rest of the graphene film is in contact with the germanium sheet without the insulating layer and forms a Schottky junction; a metal electrode in ohmic contact with the graphene is arranged on the graphene film, and the metal electrode is directly above the insulating layer and does not exceed the area of the insulating layer; the germanium sheet is fixed on a glass substrate; when light irradiates the wavelength detector from the first photodetecting unit layer by layer downwards or backwards, the current ratio of the two photodetecting units gradually changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the detectable wavelength range includes 265-1550 nm; Alternatively, the wavelength detector comprises a 30-100 nm thick metal interdigital electrode or a pair of 0.34-30 nm thick two-dimensional thin film material electrodes arranged on the upper and lower surfaces of a semiconductor wafer to form a Schottky junction, a heterojunction or an ohmic contact, and the semiconductor wafer and the electrodes on both sides form two photodetecting units; when light irradiates the wavelength detector from the upper surface of the semiconductor wafer layer by layer backwards, the current ratio of the two photodetecting units gradually changes with the increase of the wavelength of the detected light, so that the wavelength of the detected light can be identified according to the current ratio, and the detectable wavelength range includes 265-2000 nm.

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