A self-driven heterojunction wavelength sensing method and wavelength sensor

Abstract

The present invention provides a self-driven heterojunction wavelength sensing method and a wavelength sensor, which include: building a heterojunction wavelength sensor capable of realizing self-driven heterojunction wavelength sensing, and then making the light to be measured pass through a first heterojunction photodetector, a substrate and a second heterojunction photodetector in sequence. The first heterojunction photodetector absorbs part of the light to be measured, and its transmittance gradually increases with the wavelength. The second heterojunction photodetector absorbs the light transmitted through the first heterojunction photodetector; then detecting the photocurrent response intensity I in the first heterojunction photodetector ph1 and the photocurrent response intensity I in the second heterojunction photodetector ph2 ; finally, fitting a photocurrent ratio-wavelength curve with monotonicity in the wavelength range to be measured through the ratio of I ph1 and I ph2 to complete optical wave sensing. The present invention has the advantages of simple process, low cost, no need for external bias voltage, high resolution, and sensitive and stable wavelength sensing, providing new ideas and directions for the design of wavelength sensors.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a self-driven heterojunction wavelength sensing method and a wavelength sensor. Background Art

[0002] As the core component of wavelength detection technology, wavelength sensors play a key role in many fields such as image sensing, optical communication, environmental monitoring, and medical testing. They can quantitatively identify wavelengths within a certain wavelength range. Their working principle is to detect photons absorbed or reflected by objects in the target scene and interact with the outside world to achieve wavelength recognition.

[0003] At present, wavelength sensors are mainly divided into filtering type and non-filtering type. Filtering type wavelength sensors combine filters with photodetectors, and use the filter's selective transmission or reflection characteristics for specific wavelengths to achieve wavelength detection. This type of sensor has a relatively simple structure and high wavelength selection accuracy, but it requires a combination of multiple filters and multiple detectors to achieve wide spectrum detection, which not only increases the complexity of the system, but also makes miniaturization difficult to achieve. In addition, the filter performance is easily affected by the environment and temperature, and the stability is poor.

[0004] The filterless wavelength sensor can realize filtering and detection functions at the same time, and it does not require additional optical filters. Common filterless wavelength sensors include vertical stacking type, gradient bandgap type and narrowband material type. The vertical stacking type forms multiple PN junctions with different semiconductor materials and stacks them vertically. Based on the principle that light with a longer wavelength penetrates the absorption layer deeper than light with a shorter wavelength, incident light of different wavelengths forms a wavelength-related photocurrent at different PN junctions, and wavelength detection is achieved by comparing the difference in photocurrent. The gradient bandgap type uses semiconductor materials with a gradual bandgap. Light of different wavelengths is absorbed at different positions of the material. The change in bandgap causes the distribution of photogenerated carriers to be related to the wavelength, thereby achieving wavelength detection. The narrowband material type is based on the sensitivity of narrowband materials to light of specific wavelengths, and determines the wavelength of the incident light by detecting the intensity or distribution of the photocurrent. However, existing filterless wavelength sensors also have problems. On the one hand, they mainly use PN and PIN junctions, which require complex processes to accurately control the doping concentration and junction depth, and the manufacturing process is complex and costly. On the other hand, its wavelength response range is narrow, its light absorption efficiency and sensitivity are low, its temperature stability is poor, and its performance is limited in self-driven mode. It often requires an external bias to improve performance, and cannot achieve self-driven wavelength recognition. In addition, filterless wavelength sensors based on heterojunction photodetectors are mainly based on single-type carrier detection. Most of them are heterojunction devices with electron-dominated transmission, with low resolution, and the single detection mechanism lacks self-compensation capabilities. In summary, current wavelength sensors have deficiencies in performance, cost, stability, etc., which limits their application in this industry. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is how to overcome the shortcomings of wavelength sensors in the prior art in terms of performance, cost, stability, etc., and to provide a self-driven heterojunction wavelength sensing method and a wavelength sensor.

[0006] In order to solve the above technical problems, the present invention provides a self-driven heterojunction wavelength sensing method, which comprises: step S1, providing a substrate, and arranging a first electrode layer and a second electrode layer on both sides of the substrate respectively; step S2, arranging a first heterojunction photodetector on the first electrode layer, and arranging a second heterojunction photodetector on the second electrode layer, wherein the transmittance of the first heterojunction photodetector in the wavelength range to be measured is higher than that of the second heterojunction photodetector; step S3, arranging a front electrode layer on the first heterojunction photodetector, and at the same time, arranging a back electrode layer on the second heterojunction photodetector. The method comprises: first, a first heterojunction photodetector and a second heterojunction photodetector, wherein the first heterojunction photodetector has a plurality of light sources, and the first heterojunction photodetector has a plurality of light sources. The first heterojunction photodetector has a plurality of light sources, and the second ... ph1 , and simultaneously detect the photocurrent response intensity I in the second heterojunction photodetector ph2 ; Step S6, by I ph1 and I ph2 The ratio of is used to fit a monotonic photocurrent ratio-wavelength curve within the wavelength range to be measured to complete light wave sensing.

[0007] In one embodiment of the present invention, the energy difference of the first valence band edge at the first heterojunction interface is greater than the energy difference of the first conduction band edge, so that the photogenerated electrons are separated by the built-in electric field of the first heterojunction, and the first electrode layer collects the holes separated by the first heterojunction; the energy difference of the second conduction band edge at the second heterojunction interface is greater than the energy difference of the second valence band edge, so that the photogenerated holes are separated by the built-in electric field of the second heterojunction, and the second electrode layer collects the electrons separated by the second heterojunction.

[0008] In one embodiment of the present invention, in step S2, the preparation method of the first heterojunction photodetector is: the electron transport layer and the p-type crystalline silicon light absorption layer are connected to each other, and a first heterojunction is formed at the junction of the electron transport layer and the p-type crystalline silicon light absorption layer, wherein the p-type crystalline silicon light absorption layer is connected to the first electrode layer.

[0009] In one embodiment of the present invention, the doping concentration of the p-type crystalline silicon light absorbing layer is 10 15 ~10 18 cm -3 The electron transport layer substrate is SnO 2 、TiO 2 , Ga 2 O 3 or ZnO, and its doping concentration is 10 16 ~10 17 cm -3 .

[0010] In one embodiment of the present invention, in step S2, the preparation method of the second heterojunction photodetector is: the hole transport layer and the n-type crystalline silicon light absorption layer are connected to each other, and a second heterojunction is formed at the junction of the hole transport layer and the n-type crystalline silicon light absorption layer, wherein the n-type crystalline silicon light absorption layer is connected to the second electrode layer.

[0011] In one embodiment of the present invention, the doping concentration of the n-type crystalline silicon light absorbing layer is 10 15 ~10 18 cm -3 The substrate of the hole transport layer is NiO, MoO 3 ,CoO or Bi 2 O 3 One of them, and its doping concentration is 10 18 ~10 19 cm -3 .

[0012] In one embodiment of the present invention, within a part of the wavelength range to be measured, as the wavelength to be measured increases, the photocurrent response intensity I ph1 The change process and the photocurrent response intensity I in the second heterojunction photodetector ph2 The monotonicity of the change process is the opposite.

[0013] The present invention also provides a wavelength sensor, which is used to perform light wave sensing to be measured through the above-mentioned self-driven heterojunction wavelength sensing method, and includes: a substrate; a first electrode layer and a second electrode layer, the first electrode layer and the second electrode layer are respectively connected to the opposite sides of the substrate; a first heterojunction photodetector, the first heterojunction photodetector is connected to the first electrode layer, part of the light wave to be measured is absorbed by the first heterojunction and forms a photocurrent under the action of a corresponding built-in electric field; a second heterojunction photodetector, the second heterojunction photodetector is connected to the second electrode layer, the light wave passing through the first heterojunction photodetector is absorbed by the second heterojunction and forms a photocurrent under the action of a corresponding built-in electric field; a front electrode and a back electrode, the front electrode is connected to the first heterojunction photodetector, and the back electrode is connected to the second heterojunction photodetector, wherein a gap area is provided on the front electrode to expose at least part of the first heterojunction photodetector.

[0014] In one embodiment of the present invention, the back electrode, the second heterojunction photodetector, the second electrode layer, the substrate, the first electrode layer, the first heterojunction photodetector and the front electrode are stacked and connected in sequence from bottom to top in the height direction of the wavelength sensor.

[0015] In one embodiment of the present invention, the first heterojunction photodetector includes an electron transport layer and a p-type crystalline silicon light absorption layer combined with each other to form the first heterojunction, wherein the p-type crystalline silicon light absorption layer is connected to the first electrode layer; the second heterojunction photodetector includes a hole transport layer and an n-type crystalline silicon light absorption layer combined with each other to form the second heterojunction, wherein the n-type crystalline silicon light absorption layer is connected to the second electrode layer.

[0016] In one embodiment of the present invention, the electron transport layer, the p-type crystalline silicon light absorption layer, the hole transport layer and the n-type crystalline silicon light absorption layer are all planar two-dimensional structures, wherein the electron transport layer has a thickness of 40 to 160 nm, the p-type crystalline silicon light absorption layer has a thickness of 2 to 10 μm, the hole transport layer has a thickness of 40 to 160 nm, the n-type crystalline silicon light absorption layer has a thickness of 10 to 100 μm, and the n-type crystalline silicon light absorption layer has a thickness greater than that of the p-type crystalline silicon light absorption layer.

[0017] In one embodiment of the present invention, the substrate is a thin film structure or layer structure that is transparent within the wavelength range to be measured, the first electrode layer and the second electrode layer are transparent materials within the wavelength range to be measured, the front electrode layer is a grid electrode, and the back electrode layer is an opaque conductive metal material.

[0018] The above technical solution of the present invention has the following advantages compared with the prior art:

[0019] The self-driven heterojunction wavelength sensing method and wavelength sensor described in the present invention allow the incident light to pass through two mutually vertically stacked heterojunction photodetectors in sequence, thereby obtaining a photocurrent ratio-wavelength curve within the wavelength range to be measured to complete light wave sensing. On the one hand, the above process ensures the transmission of the transmitted light, while reducing the influence of the reflected light on the surface of the second heterojunction photodetector on the first heterojunction photodetector. On the other hand, it can also achieve the purpose of improving the sensitivity and stability of the wavelength sensor by adjusting the dominant transmission mode of the two heterojunction photodetectors and the dual-carrier detection mechanism. Compared with the existing conventional silicon-based optoelectronic devices implemented by PIN or PN junctions, the present application has the advantages of simple process, low cost, no need for external bias, high resolution, and sensitive and stable wavelength sensing, providing new ideas and directions for the design of wavelength sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0021] Figure 1 is a schematic structural diagram of a self-driven heterojunction wavelength sensor in a preferred embodiment of the present invention;

[0022] Figure 2 yes Figure 1 A schematic diagram of the photocurrent formation principle in the first heterojunction photodetector and the second heterojunction photodetector in the self-driven heterojunction wavelength sensor;

[0023] Figure 3 In the preferred embodiment of the present invention, the incident light power density is 0.3 mW cm -2 , light absorption rate-wavelength curve of the first heterojunction photodetector under vertical irradiation of incident light;

[0024] Figure 4 In the preferred embodiment of the present invention, the incident light power density is 0.3 mW cm -2 , light absorption rate-wavelength curve of the second heterojunction photodetector under vertical irradiation of incident light;

[0025] Figure 5 The incident light power density of the curve in the preferred embodiment of the present invention is 0.3 mW cm -2 , a photocurrent ratio-wavelength curve of the wavelength sensor described in Example 1 under vertical incident light;

[0026] Figure 6 In the preferred embodiment of the present invention, the incident light power density is 0.3 mW cm -2, the photocurrent density-wavelength curve of the first heterojunction photodetector under vertical irradiation of incident light;

[0027] Figure 7 In the preferred embodiment of the present invention, the incident light power density is 0.3 mW cm -2 , the photocurrent density-wavelength curve of the second heterojunction photodetector under vertical irradiation of incident light;

[0028] Figure 8 The incident light power density is 0.3 mW cm -2 , the photocurrent ratio-wavelength curve of the wavelength sensor under vertical incident light irradiation and the incident light power density of the preferred embodiment is 0.3mWcm -2 , the photocurrent ratio-wavelength curve of the wavelength sensor under vertical incident light;

[0029] Fig. 9 The incident light power density is 0.3 mW cm -2 , the transmittance-wavelength curve of the second heterojunction photodetector under vertical irradiation of incident light;

[0030] Fig.10 The incident light power density is 0.3 mW cm -2 , photocurrent ratio-wavelength curve of wavelength sensor under vertical incident light.

[0031] Explanation of the reference numerals in the drawings in the specification: 11. front electrode layer; 12. electron transport layer; 13. p-type crystalline silicon light absorption layer; 14. first electrode layer; 15. substrate; 16. second electrode layer; 17. n-type crystalline silicon light absorption layer; 18. hole transport layer; 19. back electrode layer; 21. first valence band; 22. first conduction band; 23. second valence band; 24. second conduction band. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0033] Embodiment 1

[0034] This embodiment provides a self-driven heterojunction wavelength sensing method, which is used to obtain a photocurrent ratio-wavelength curve within a wavelength range to be measured by two heterojunction photodetectors stacked vertically to complete light wave sensing, and includes the following steps:

[0035] Step S1, providing a substrate 15, and disposing a first electrode layer 14 and a second electrode layer 16 on both sides of the substrate 15 respectively;

[0036] In this embodiment, before the light to be measured is incident, it is necessary to build a heterojunction wavelength sensor that can realize self-driven heterojunction wavelength sensing. In this embodiment, the substrate 15 is a transparent thin film structure or layer structure within the wavelength range to be measured, which serves as a support to connect the first electrode layer 14 and the second electrode layer 16, and it can also reduce the reflection effect of light during transmission. Further, the thickness of the substrate 15 in this embodiment is 1000μm. In different implementations, the thickness of the substrate 15 can be set to 100μm to 10mm according to actual use requirements. It can also be set to a transparent thin film structure or layer structure within the wavelength range to be measured of different materials. The present invention does not make specific restrictions on this.

[0037] Furthermore, the first electrode layer 14 and the second electrode layer 16 are respectively connected to two opposite sides of the substrate 15 in the thickness direction. In this embodiment, the first electrode layer 14 and the second electrode layer 16 are planar two-dimensional structures that are transparent within the wavelength range to be measured.

[0038] Step S2, a first heterojunction photodetector is arranged on the first electrode layer 14, the first heterojunction photodetector is connected to the first electrode layer 14, and a second heterojunction photodetector is arranged on the second electrode layer 16. Part of the light waves within the wavelength range to be measured are absorbed by the first heterojunction and form a photocurrent under the action of the corresponding built-in electric field, and part of the light waves within the wavelength range to be measured pass through the first heterojunction photodetector, and then are absorbed by the second heterojunction photodetector and form a photocurrent under the action of the corresponding built-in electric field.

[0039] Further, in step S2, the electron transport layer 12 and the p-type crystalline silicon light absorption layer 13 are connected to each other to form the first heterojunction photodetector, and the electron transport layer 12 and the p-type crystalline silicon light absorption layer 13 are connected to each other to form a first heterojunction, wherein the p-type crystalline silicon light absorption layer 13 is connected to the first electrode layer 14. The electron transport layer 12 and the p-type crystalline silicon light absorption layer 13 are two-dimensional structures with a planar morphology, wherein the thickness of the p-type crystalline silicon light absorption layer 13 is 5 μm, and the doping concentration is 3×10 17 cm -3 The thickness of the electron transport layer 12 is 60 nm and the doping concentration is 1×10 17 cm -3 The substrate is preferably SnO 2 In different implementations, the thickness of the p-type crystalline silicon light absorbing layer 13 can be set to 2-10 μm, and its doping concentration can be set to 10 15 ~10 18 cm -3 The thickness of the electron transport layer 12 can be set to 40 to 160 nm, and its doping concentration can be set to 10 16~10 17 cm -3 , the substrate can be set to SnO 2 、TiO 2 , Ga 2 O 3 Or one of ZnO, the present invention is not specifically limited to this.

[0040] Correspondingly, the hole transport layer 18 and the n-type crystalline silicon light absorption layer 17 are connected to each other to form a second heterojunction photodetector, and the hole transport layer 18 and the n-type crystalline silicon light absorption layer 17 are connected to each other to form a second heterojunction, wherein the n-type crystalline silicon light absorption layer 17 is connected to the second electrode layer 16. The hole transport layer 18 and the n-type crystalline silicon light absorption layer 17 are both planar two-dimensional structures, wherein the n-type crystalline silicon light absorption layer 17 has a thickness of 40 μm and a doping concentration of 1×10 16 cm -3 The hole transport layer 18 has a thickness of 60 nm and a doping concentration of 1×10 19 cm -3 In different embodiments, the thickness of the n-type crystalline silicon light absorbing layer 17 can be set to 10-100 μm, and the doping concentration can be set to 10 15 ~10 18 cm -3 , it is only necessary to ensure that the thickness of the n-type crystalline silicon light absorption layer 17 is greater than the thickness of the p-type crystalline silicon light absorption layer 13; the thickness of the hole transport layer 18 can be set to 40-160nm, and its doping concentration can be set to 10 18 ~10 19 cm -3 , the substrate can be set as NiO, MoO 3 ,CoO or Bi 2 O 3 The present invention does not impose any specific limitation on this.

[0041] In this embodiment, the energy difference of the first valence band 21 side at the first heterojunction interface is greater than the energy difference of the first conduction band 22 side, so as to separate the photogenerated electrons through the built-in electric field of the first heterojunction, and the first electrode layer 14 collects the holes separated by the first heterojunction. Correspondingly, the energy difference of the second conduction band 24 side at the second heterojunction interface is greater than the energy difference of the second valence band 23 side, so as to separate the photogenerated holes through the built-in electric field of the second heterojunction, and the second electrode layer 16 collects the electrons separated by the second heterojunction, thereby forming photocurrents in the first heterojunction photodetector and the second heterojunction photodetector, respectively. Based on this, the first electrode layer 14 in this embodiment is used to realize the emission of the transmitted light in the first heterojunction photodetector and collect the holes in the first heterojunction at the same time; the second electrode layer 16 is used to make the transmitted light of the first heterojunction photodetector incident into the second heterojunction photodetector and collect the electrons in the second heterojunction.

[0042] Step S3, setting a front electrode layer 11 on the first heterojunction photodetector, and at the same time, setting a back electrode layer 19 on the second heterojunction photodetector, wherein a gap area is provided on the front electrode layer 11 to expose at least part of the first heterojunction photodetector.

[0043] Furthermore, in this embodiment, the back electrode, the second heterojunction photodetector, the second electrode layer 16, the substrate 15, the first electrode layer 14, the first heterojunction photodetector and the front electrode are stacked and connected in sequence from bottom to top in the height direction of the wavelength sensor.

[0044] Furthermore, the front electrode layer 11 in this embodiment is a grid-shaped electrode, and the grid structures thereon are separated from each other and arranged non-densely.

[0045] Furthermore, the substrate of the two-dimensional structure of the back electrode plane morphology in this embodiment is preferably opaque Au. In different implementations, the substrate of the back electrode layer 19 can be configured as different opaque conductive metal materials according to actual use requirements.

[0046] This completes the construction of the self-driven heterojunction wavelength sensor. The schematic diagram of its structure can be found in Figure 1 shown.

[0047] Step S4, making the light to be measured incident from the gap area toward the back electrode layer 19, and pass through the first heterojunction photodetector, the substrate 15 and the second heterojunction photodetector in sequence, wherein the first heterojunction photodetector absorbs part of the light to be measured and transmits part of the light to be measured, and its transmittance increases with the increase of wavelength within the wavelength range to be measured, and the second heterojunction photodetector absorbs the light passing through the first heterojunction photodetector.

[0048] Furthermore, based on the stacked layer structure in this embodiment, the light to be measured needs to be incident through the gap region in a direction perpendicular to the first heterojunction photodetector.

[0049] Furthermore, the incident light wavelength in this embodiment is 200-900 nm and the optical power density is 0.3 mW cm -2 The first heterojunction photodetector has a stable and high absorption rate in the wavelength range of 300-450nm, while the absorption rate of light with a wavelength greater than 450nm decreases with the increase of wavelength. The second heterojunction photodetector has a significant absorption of light with a wavelength of 450-900nm passing through the first heterojunction photodetector. Based on this, the wavelength range to be measured with monotonicity is 450-900nm. Figure 2 As shown, in this embodiment, the incident light is absorbed by the p-type crystalline silicon light absorption layer 13, and photogenerated electron-hole pairs are generated in the p-type crystalline silicon light absorption layer 13. Driven by the built-in electric field formed by the first heterojunction, the photogenerated electrons move to the electron transport layer 12, and the photogenerated holes move to the first electrode layer 14, thereby forming a photocurrent in the first heterojunction photodetector; next, the light transmitted from the p-type crystalline silicon light absorption layer 13 passes through the first electrode, the substrate 15, and the second electrode in sequence, and is absorbed by the n-type crystalline silicon light absorption layer 17, and photogenerated electron-hole pairs are generated in the p-type crystalline silicon light absorption layer 17. Driven by the built-in electric field formed by the second heterojunction, the photogenerated holes move to the hole transport layer 18, and the photogenerated electrons move to the second electrode layer 16, thereby forming a photocurrent in the second heterojunction photodetector.

[0050] Step S5: Detecting the photocurrent response intensity I in the first heterojunction photodetector ph1 , and simultaneously detect the photocurrent response intensity I in the second heterojunction photodetector ph2 .

[0051] Furthermore, in the first heterojunction photodetector, the p-type crystalline silicon light absorption layer 13 is relatively thin, so that the light absorption rate for wavelengths of 300 to 450 nm is relatively stable and high, while the light absorption rate for wavelengths above 450 nm is not stable, see Figure 3 As shown in FIG. 1 , as the wavelength increases, the light absorption rate in the first heterojunction photodetector increases first and then decreases. Correspondingly, the n-type crystalline silicon light absorption layer 17 of the second heterojunction photodetector is thicker, so the light absorption rate for all visible light and near-infrared bands is higher. Figure 4As shown, the light absorption rate of the second heterojunction photodetector increases as the wavelength increases. Based on this, in this embodiment, within the wavelength range of 450 to 900 nm, as the measured wavelength increases, the monotonicity of the photocurrent response intensity change process in the first heterojunction photodetector is opposite to that of the photocurrent response intensity change process in the second heterojunction photodetector.

[0052] Furthermore, the photocurrent response intensity is reflected by detecting the photocurrent density in the first heterojunction photodetector and the second heterojunction photodetector, wherein the photocurrent density is positively correlated with the light absorption rate of the first heterojunction photodetector and the second heterojunction photodetector.

[0053] Step S6: By I ph1 and I ph2 The ratio of is fitted to a photocurrent ratio-wavelength curve with monotonicity in the wavelength range to be measured, see Figure 5 As shown, the photocurrent ratio strictly increases monotonically in the wavelength range of 450 to 900 nm, thereby achieving wavelength sensing in the range of 450 to 900 nm.

[0054] Furthermore, in the process of photocurrent formation, the photocurrent density is positively correlated with the light absorption rate. Therefore, this embodiment verifies the photocurrent intensity by comparing the photocurrent density. Figure 6 and Figure 7 As shown, it can be further proved that the photocurrent ratio in this embodiment is monotonic within the wavelength range to be measured.

[0055] Embodiment 2

[0056] This embodiment provides a wavelength sensor, which is used to perform optical wave sensing within a wavelength range to be measured by using the self-driven heterojunction wavelength sensing method described in the first embodiment, and includes:

[0057] A substrate 15, wherein the substrate 15 is a thin film structure or a layer structure that is transparent within the wavelength range to be measured;

[0058] A first electrode layer 14 and a second electrode layer 16, wherein the first electrode layer 14 and the second electrode layer 16 are respectively connected to two opposite sides of the substrate 15, wherein the first electrode layer 14 and the second electrode layer 16 are transparent materials within the wavelength range to be measured, the front electrode layer 11 is a grid electrode, and the back electrode layer 19 is an opaque conductive metal material;

[0059] A first heterojunction photodetector, wherein the first heterojunction photodetector is connected to the first electrode layer 14, and part of the photons within the wavelength range to be measured are absorbed by the first heterojunction, and a photocurrent is formed under the action of a built-in electric field formed by the first heterojunction. Further, the first heterojunction photodetector includes an electron transport layer 12 and a p-type crystalline silicon light absorption layer 13 combined with each other to form the first heterojunction, and the p-type crystalline silicon light absorption layer 13 is connected to the first electrode layer 14, wherein the electron transport layer 12 and the p-type crystalline silicon light absorption layer 13 are both planar two-dimensional structures, the thickness of the electron transport layer 12 is 60nm, and the thickness of the p-type crystalline silicon light absorption layer 13 is 5μm;

[0060] A second heterojunction photodetector, wherein the second heterojunction photodetector is connected to the second electrode layer 16, and photons penetrating the first heterojunction are absorbed by the second heterojunction and form a photocurrent under the action of a built-in electric field formed by the second heterojunction. Further, the second heterojunction photodetector includes a hole transport layer 18 and an n-type crystalline silicon light absorption layer 17 combined with each other to form the second heterojunction, and the n-type crystalline silicon light absorption layer 17 is connected to the second electrode layer 16, wherein the hole transport layer 18 and the n-type crystalline silicon light absorption layer 17 are both planar two-dimensional structures, the thickness of the n-type crystalline silicon light absorption layer 17 is 40 μm, and the thickness of the hole transport layer 18 is 60 nm;

[0061] A front electrode and a back electrode, the front electrode is connected to the first heterojunction photodetector, and the back electrode is connected to the second heterojunction photodetector, wherein a gap area is provided on the front electrode to expose at least a portion of the first heterojunction photodetector.

[0062] Furthermore, the back electrode, the second heterojunction photodetector, the second electrode layer 16, the substrate 15, the first electrode layer 14, the first heterojunction photodetector and the front electrode are stacked and connected in sequence from bottom to top in the height direction of the wavelength sensor.

[0063] Comparative Example 1

[0064] This comparative example provides another self-driven heterojunction wavelength sensor, whose main structural setting is the same as that of Example 1, except that the second heterojunction photodetector in Example 1 is replaced by the first heterojunction photodetector, that is, the two vertically stacked heterojunction photodetectors are heterojunctions formed by the combination of a p-type crystalline silicon light absorption layer and an electron transport layer. Based on the above structural setting, this comparative example tests the incident wavelength of 200 to 900 nm, the incident light is vertically incident, and the incident light power density is 0.3 mW cm -2 The photocurrent ratio-wavelength curve is shown in Figure 8As shown, curve 81 is the photocurrent ratio-wavelength curve in the comparative example, and curve 82 is the photocurrent ratio-wavelength curve in the first embodiment. It can be seen that the photocurrent ratio-wavelength curve in the comparative example is strictly monotonically increasing only within 450-700nm, and fails to cover the 750-900nm band. Therefore, in the visible light and near-infrared bands, the working bandwidth and sensitivity of the dual-carrier self-driven heterojunction wavelength sensor structure in the first embodiment are better than the silicon-based heterojunction wavelength sensor for single-carrier detection in the first comparative example.

[0065] Comparative Example 2

[0066] This comparative example provides another self-driven heterojunction wavelength sensor, which is to exchange the setting positions of the first heterojunction photodetector and the second heterojunction photodetector in Example 1. Based on this, the second heterojunction photodetector in this comparative example absorbs part of the light within the wavelength range to be measured and transmits the light within the wavelength range to be measured, and the first heterojunction photodetector absorbs the light within the wavelength range to be measured and passes through the second heterojunction photodetector.

[0067] Based on the above structure, this comparative example tests the incident light power density of 0.3mWcm -2 , the transmittance-wavelength curve of the second heterojunction photodetector under vertical incident light, see Fig. 9 As shown, the incident light power density is 0.3mWcm -2 , the photocurrent ratio-wavelength curve of the wavelength sensor under vertical incident light, see Fig.10 As shown. The wavelength sensing range of this comparative example is small and the sensitivity is low. This is because the thickness of the n-type crystalline silicon light absorption layer 17 of the second heterojunction photodetector is relatively large, and the incident light is mainly absorbed by the n-type crystalline silicon light absorption layer 17, and only a small amount of long-wave transmitted light is emitted, resulting in a very small photocurrent of the first heterojunction photodetector, and thus a relatively small photocurrent of the wavelength sensor. It can be seen that in part of the visible light and near-infrared bands, the working bandwidth and sensitivity of the dual-carrier self-driven heterojunction wavelength sensor structure in Example 1 are better than those of this comparative example.

[0068] In summary, the self-driven heterojunction wavelength sensing method and wavelength sensor described in the present invention have the following advantages:

[0069] First of all, the present application is different from the existing silicon-based optoelectronic devices using PIN or PN junctions. It is simple to manufacture, low-cost, and has a wider wavelength response range. In particular, the performance of the present application is not limited in the self-driving mode, so no external bias is required during use, further simplifying the use process.

[0070] Secondly, in the present application, the incident light first enters the first heterojunction photodetector, and the transmitted light enters the second heterojunction photodetector. The two heterojunction photodetectors are connected by a transparent substrate 15 whose thickness is much greater than the sensing wavelength, which not only ensures the transmission of the transmitted light, but also reduces the influence of the reflected light on the surface of the second heterojunction photodetector on the first heterojunction photodetector.

[0071] In addition, the present invention adopts two types of carrier detection. The first heterojunction photodetector is an electron-dominated transmission type heterojunction device, and the second heterojunction photodetector is a hole-dominated transmission type heterojunction device, thereby effectively improving the sensitivity of the wavelength sensor. The dual-carrier detection mechanism also improves the stability of the wavelength sensor.

[0072] Compared with the existing conventional silicon-based optoelectronic devices implemented using PIN or PN junctions, this application has the advantages of simple process, low cost, no need for external bias, high resolution, and sensitive and stable wavelength sensing, providing new ideas and directions for the design of wavelength sensors.

[0073] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A self-driven heterojunction wavelength sensing method, characterized in that: include: Step S1, providing a substrate, and respectively disposing a first electrode layer and a second electrode layer on both sides of the substrate; Step S2, arranging a first heterojunction photodetector on the first electrode layer, and arranging a second heterojunction photodetector on the second electrode layer, wherein the transmittance of the first heterojunction photodetector in the wavelength range to be measured is higher than that of the second heterojunction photodetector; Step S3, providing a front electrode layer on the first heterojunction photodetector, and at the same time, providing a back electrode layer on the second heterojunction photodetector, wherein a gap region is provided on the front electrode layer to expose at least a portion of the first heterojunction photodetector; Step S4, allowing the light to be measured to be incident from the gap region toward the back electrode layer, and pass through the first heterojunction photodetector, the substrate, and the second heterojunction photodetector in sequence, wherein the first heterojunction photodetector absorbs part of the light to be measured, and its transmittance increases with the increase of wavelength within the wavelength range to be measured, and the second heterojunction photodetector absorbs the light that passes through the first heterojunction photodetector; Step S5: Detecting the photocurrent response intensity I in the first heterojunction photodetector ph1 , and simultaneously detect the photocurrent response intensity I in the second heterojunction photodetector ph2 ; Step S6: By I ph1 and I ph2 The ratio of is used to fit a monotonic photocurrent ratio-wavelength curve within the wavelength range to be measured to complete wavelength sensing.

2. The self-driven heterojunction wavelength sensing method according to claim 1, characterized in that: The energy difference of the first valence band edge of the first heterojunction at the interface is greater than the energy difference of the first conduction band edge, so that the photogenerated electrons are separated by the built-in electric field of the first heterojunction, and the first electrode layer collects the holes separated by the first heterojunction; The energy difference of the second conduction band edge of the second heterojunction at the interface is greater than the energy difference of the second valence band edge, so that the photogenerated holes are separated by the built-in electric field of the second heterojunction, and the second electrode layer collects the electrons separated by the second heterojunction.

3. The self-driven heterojunction wavelength sensing method according to claim 1, characterized in that: In step S2, the preparation method of the first heterojunction photodetector is: the electron transport layer and the p-type crystalline silicon light absorption layer are connected to each other, and a first heterojunction is formed at the junction of the electron transport layer and the p-type crystalline silicon light absorption layer, wherein the p-type crystalline silicon light absorption layer is connected to the first electrode layer.

4. The self-driven heterojunction wavelength sensing method according to claim 3, characterized in that: The doping concentration of the p-type crystalline silicon light absorbing layer is 10 15 ~10 18 cm -3 The electron transport layer substrate is one of SnO2, TiO2, Ga2O3 or ZnO, and its doping concentration is 10 16 ~10 17 cm -3 .

5. The self-driven heterojunction wavelength sensing method according to claim 1, characterized in that: In step S2, the preparation method of the second heterojunction photodetector is: connect the hole transport layer and the n-type crystalline silicon light absorption layer to each other, and form a second heterojunction at the junction of the hole transport layer and the n-type crystalline silicon light absorption layer, wherein the n-type crystalline silicon light absorption layer is connected to the second electrode layer.

6. The self-driven heterojunction wavelength sensing method according to claim 5, characterized in that: The doping concentration of the n-type crystalline silicon light absorbing layer is 10 15 ~10 18 cm -3 The substrate of the hole transport layer is one of NiO, MoO3, CoO or Bi2O3, and its doping concentration is 10 18 ~10 19 cm -3 .

7. The self-driven heterojunction wavelength sensing method according to claim 1, characterized in that: In the wavelength range to be measured, as the wavelength to be measured increases, the photocurrent response intensity I ph1 The change process and the photocurrent response intensity I in the second heterojunction photodetector ph2 The monotonicity of the change process is the opposite.

8. A wavelength sensor, characterized in that: The method is used for sensing the optical wave to be measured by the self-driven heterojunction wavelength sensing method according to any one of claims 1 to 7, comprising: substrate; A first electrode layer and a second electrode layer, wherein the first electrode layer and the second electrode layer are respectively connected to two opposite sides of the substrate; A first heterojunction photodetector, wherein the first heterojunction photodetector is connected to the first electrode layer, and a portion of the light wave to be measured is absorbed by the first heterojunction and forms a photocurrent under the action of a corresponding built-in electric field; A second heterojunction photodetector, wherein the second heterojunction photodetector is connected to the second electrode layer, and the light wave passing through the first heterojunction photodetector is absorbed by the second heterojunction and forms a photocurrent under the action of a corresponding built-in electric field; A front electrode and a back electrode, the front electrode is connected to the first heterojunction photodetector, and the back electrode is connected to the second heterojunction photodetector, wherein a gap area is provided on the front electrode to expose at least a portion of the first heterojunction photodetector.

9. The wavelength sensor according to claim 8, characterized in that: The back electrode, the second heterojunction photodetector, the second electrode layer, the substrate, the first electrode layer, the first heterojunction photodetector and the front electrode are sequentially stacked and connected from bottom to top in the height direction of the wavelength sensor.

10. The wavelength sensor according to claim 8, characterized in that: The first heterojunction photodetector includes an electron transport layer and a p-type crystalline silicon light absorption layer combined with each other to form the first heterojunction, wherein the p-type crystalline silicon light absorption layer is connected to the first electrode layer; the second heterojunction photodetector includes a hole transport layer and an n-type crystalline silicon light absorption layer combined with each other to form the second heterojunction, wherein the n-type crystalline silicon light absorption layer is connected to the second electrode layer, wherein the electron transport layer, the p-type crystalline silicon light absorption layer, the hole transport layer and the n-type crystalline silicon light absorption layer are all planar two-dimensional structures, wherein the electron transport layer has a thickness of 40 to 160 nm, the p-type crystalline silicon light absorption layer has a thickness of 2 to 10 μm, the hole transport layer has a thickness of 40 to 160 nm, the n-type crystalline silicon light absorption layer has a thickness of 10 to 100 μm, and the n-type crystalline silicon light absorption layer has a thickness greater than that of the p-type crystalline silicon light absorption layer.

Images