Infrared narrow-band photoelectric device and preparation method thereof

Abstract

The preparation method comprises the following steps: preparing an electron transport layer on FTO glass, preparing an active absorption layer on the electron transport layer, carrying out cadmium chloride treatment on the active absorption layer to passivate defects, preparing a cuprous thiocyanate layer or a nickel oxide layer on the active absorption layer as a hole transport layer, and preparing a hole transport layer on the hole transport layer. When the hole transport layer is a nickel oxide layer, a cuprous thiocyanate layer is prepared on the hole transport layer, annealing is performed at 250 + / -5 DEG C for 10-30 min to diffuse copper to an FTO glass interface, and a transparent electrode is prepared on the surface of the cuprous thiocyanate layer. High-temperature annealing treatment is carried out after the cuprous thiocyanate layer is prepared, copper is fully diffused and doped to the active absorption layer, the P-type doping concentration is improved, an extremely narrow built-in electric field is obtained, the carrier collection narrowing effect is achieved, and the advantages of being high in stability, long in service life, high in response speed and high in efficiency are achieved. The invention has the advantages of simple structure, high responsivity, strong band selectivity, adjustable response band width, narrow full width at half maximum and the like.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic device technology, specifically to an infrared narrowband optoelectronic device and its fabrication method. Background Technology

[0002] Existing infrared narrowband optoelectronic devices mainly achieve narrowband detection by combining bandpass filters with the front integration of ordinary broadband optoelectronic devices. However, the introduction of filters will cause additional optical losses and reduce quantum efficiency. At the same time, spectral tuning requires mechanical adjustment of the filters, making it difficult to achieve dynamic tunability.

[0003] While using a carrier collection narrowing mechanism to achieve selective detection in a single infrared band can avoid the use of filters, the realization of collection narrowing is highly dependent on a relatively thick active layer film (>10 μm), which leads to a decrease in response speed (>1ms) and spectral selectivity (FWHM>50 nm), thus limiting the detection accuracy and making it difficult to meet the requirements of high-precision detection.

[0004] Therefore, it is of great significance to research and develop a filter-free narrowband optoelectronic device to achieve excellent carrier collection narrowing effect, while obtaining good response speed and response band selectivity. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing an infrared narrowband optoelectronic device and its fabrication method. It employs a thinner absorption layer (1-6 μm) and achieves narrower carrier collection by controlling the width of the space charge region, while simultaneously obtaining excellent photoresponse (EQE>30%) and detection band selectivity (FWHM ~20 nm), with a response time as low as approximately 300 ns. Furthermore, by adjusting the band gap of the active absorption layer, the response band can be wide-range tunable between 560 and 850 nm.

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a method for fabricating an infrared narrowband optoelectronic device, comprising the following steps:

[0007] S1. After preparing an electron transport layer on FTO glass, prepare an active absorption layer on the electron transport layer.

[0008] The active absorber layer is made of Cd. 1-x Zn x Te or CdSe y Te 1-y , 0≤x≤1, 0≤y≤1;

[0009] S2. After passivating defects by treating the active absorber layer with cadmium chloride, prepare a cuprous thiocyanate layer or a nickel oxide layer on the active absorber layer as a hole transport layer.

[0010] When the hole transport layer is a nickel oxide layer, a cuprous thiocyanate layer is prepared on the hole transport layer.

[0011] S3. Anneal at 250±5℃ for 10-30 min to diffuse copper to the FTO glass interface;

[0012] S4. Prepare a transparent electrode on the surface of the cuprous thiocyanate layer.

[0013] This invention involves high-temperature annealing after the preparation of the cuprous thiocyanate layer, allowing copper to fully diffuse onto the FTO glass surface. This increases the P-type doping concentration in the active absorption layer, resulting in an extremely narrow built-in electric field (<400 nm). At this point, ultraviolet and visible light are absorbed by the neutral region and have difficulty penetrating to the space charge region, making them difficult to collect by external circuitry. However, near-infrared light has a deeper penetration depth, reaching the built-in electric field region. Under the influence of the built-in electric field, photogenerated electron / hole pairs can be efficiently separated and transported, thereby enabling the device to respond to a narrow spectrum.

[0014] The active absorber layer of this invention uses Cd 1-x Zn x Te or CdSe y Te 1-y By adjusting the x and y values, the band gap of the active light-absorbing layer can be controlled, achieving a wide range of adjustable response wavelengths between 560 and 850 nm. In summary, the narrowband optoelectronic device of this invention can achieve selective absorption and selective response in different wavelength bands.

[0015] Furthermore, the thickness of the electron transport layer is 30-60 nm, the thickness of the active absorption layer is 1-6 μm, and the thickness of the hole transport layer is 30-60 nm.

[0016] Furthermore, in S2, the cadmium chloride treatment specifically involves coating the active absorber layer with a cadmium chloride solution and then heat-treating it at 390-420℃ and 600-700 torr for 20-60 minutes. This calcium chloride treatment passivates defects, promotes grain growth, and facilitates subsequent copper diffusion doping.

[0017] Furthermore, in S1, the electron transport layer is made of cadmium sulfide, tin oxide, or zinc magnesium oxide, and is prepared by radio frequency magnetron sputtering, chemical bath deposition, or spin coating.

[0018] Furthermore, in S1, the active absorber layer is prepared by near-space sublimation, magnetron sputtering, thermal evaporation, or chemical vapor deposition.

[0019] Furthermore, in S2, the cuprous thiocyanate layer and the nickel oxide layer are prepared by magnetron sputtering or spin coating.

[0020] Furthermore, in S4, the transparent electrode is made of ITO and is prepared by magnetron sputtering.

[0021] The second aspect of the present invention provides an infrared narrowband optoelectronic device prepared by the preparation method described in the first aspect.

[0022] Furthermore, the infrared narrowband optoelectronic device has a spectral half-width of 20±10nm and a photoresponse EQE>30%.

[0023] Furthermore, the infrared narrowband optoelectronic device can achieve a wide range of adjustment in response band between 560 and 850 nm by adjusting the band gap of the active absorption layer.

[0024] The beneficial effects of this invention are:

[0025] This invention involves high-temperature annealing after preparing a cuprous thiocyanate layer, which allows copper to be fully diffused and doped into the active absorption layer. This increases the P-type doping concentration of the active absorption layer, resulting in an extremely narrow built-in electric field and achieving a narrowed carrier collection effect. It has advantages such as high stability, long service life, fast response speed, high responsivity, strong band selectivity, adjustable response band width, and narrow half-height width. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the infrared narrowband optoelectronic device structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the spectral response of fully diffused copper in a narrowband optoelectronic device;

[0029] Figure 3 This is a schematic diagram of the spectral response of copper that has not diffused sufficiently in a narrowband optoelectronic device;

[0030] Figure 4 This is the copper concentration variation curve of the infrared narrowband optoelectronic device in Example 1, perpendicular to the plane.

[0031] Figure 5 These are the EDS test results for the active absorber layer in Example 2;

[0032] Figure 6 These are the XRD test results of the active absorber layer in Example 3;

[0033] Figure 7These are the spectral response diagrams of the infrared narrowband optoelectronic devices obtained in Example 1 and Comparative Examples 1-2;

[0034] Figure 8 These are the spectral response diagrams of the narrowband optoelectronic devices of Examples 1, 2, and 3. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This embodiment provides a method for fabricating an infrared narrowband optoelectronic device, including the following steps:

[0037] S1. After preparing an electron transport layer on FTO glass, the thickness of the electron transport layer is 30-60 nm. An active absorption layer is prepared on the electron transport layer, and the thickness of the active absorption layer is 1-6 μm.

[0038] The active absorber layer is made of Cd. 1-x Zn x Te or CdSe y Te 1-y , 0≤x≤1, 0≤y≤1;

[0039] S2. After passivating defects by treating the active absorber layer with cadmium chloride, a cuprous thiocyanate layer or a nickel oxide layer is prepared on the active absorber layer as a hole transport layer, wherein the thickness of the hole transport layer is 30-60 nm.

[0040] When the hole transport layer is a nickel oxide layer, a cuprous thiocyanate layer is prepared on the hole transport layer.

[0041] S3. Anneal at 250±5℃ for 10-30 min to diffuse copper to the FTO glass interface;

[0042] S4. A transparent electrode is fabricated on the surface of the cuprous thiocyanate layer to obtain a narrowband optoelectronic device, such as... Figure 1 As shown.

[0043] refer to Figure 2Taking a CdTe active absorber layer, a CdS electron transport layer, and a CuSCN hole transport layer as an example, this embodiment performs high-temperature annealing after preparing the cuprous thiocyanate layer, allowing copper to fully diffuse to the FTO glass surface. This increases the P-type doping concentration of the active absorber layer, resulting in an extremely narrow built-in electric field (<400 nm). At this point, ultraviolet and visible light are absorbed by the neutral region and have difficulty penetrating to the space charge region, making them difficult to collect by external circuitry. Near-infrared spectroscopy, however, has a deeper penetration depth, reaching the built-in electric field region. Under the influence of the built-in electric field, photogenerated electron / hole pairs can be efficiently separated and transported, thus enabling the device to respond to narrow spectra. When copper diffusion is not performed or is insufficient, the doping level is lower, resulting in a wider built-in electric field and a narrower neutral region. Ultraviolet and visible light with low penetration depths can pass through the neutral region to reach the space charge region. The generated carriers can be collected under the influence of the built-in electric field in the space charge region, forming a broadband response, such as... Figure 3 As shown. The active absorber layer uses Cd. 1-x Zn x Te or CdSe y Te 1-y By adjusting the x and y values, the band gap of the active light-absorbing layer can be modulated, achieving a wide-range tunable response band between 560 and 850 nm. In summary, the narrowband optoelectronic device of this invention can achieve selective absorption and selective response across different wavelength bands.

[0044] In a preferred embodiment, in S2, the cadmium chloride treatment specifically involves coating the active absorber layer with a cadmium chloride solution and then heat-treating it at 390-420°C and 600-700 torr for 20-60 minutes. This calcium chloride treatment passivates defects, promotes grain growth, and facilitates subsequent copper diffusion doping.

[0045] In a preferred embodiment, the electron transport layer is made of cadmium sulfide, tin oxide, or zinc magnesium oxide, and is prepared by radio frequency magnetron sputtering, chemical bath deposition, or spin coating; the active absorption layer is prepared by near-space sublimation, magnetron sputtering, thermal evaporation, or chemical vapor deposition; the cuprous thiocyanate layer and nickel oxide layer are prepared by magnetron sputtering or spin coating; and the transparent electrode is made of ITO and is prepared by magnetron sputtering.

[0046] Another embodiment provides an infrared narrowband optoelectronic device prepared by the preparation method described in the above embodiment. The infrared narrowband optoelectronic device has a spectral half-width of 20±10nm and a photoresponse EQE>30%. The infrared narrowband optoelectronic device can achieve a wide range of adjustment of the response band between 560~850 nm by adjusting the band gap of the active absorption layer.

[0047] Example 1

[0048] This embodiment relates to a method for fabricating an infrared narrowband optoelectronic device, comprising the following steps:

[0049] (1) Use deionized water mixed with Micro-90 cleaning agent to ultrasonically clean the FTO glass.

[0050] (2) Electron transport layer preparation by magnetron sputtering: FTO glass was placed in a magnetron sputtering chamber for sputtering deposition. The gas pressure was stabilized at 1~10 Pa, the power was 50 W, the substrate was rotated (25 r / min), and a 40 nm thick cadmium sulfide (CdS) was deposited by sputtering.

[0051] (3) Preparation of active absorber layer by near-space sublimation: Cadmium telluride (CdTe) powder is poured into a graphite groove, a graphite sheet coated with silicon nitride is placed on top of the groove, and the graphite sheet is pressed down with a graphite block. Cadmium telluride source is prepared by near-space sublimation. The temperature is set at 550℃ in the upper temperature zone and 700℃ in the lower temperature zone, the gas pressure is set at 5 torr, and the time is 40 min. The prepared cadmium telluride source is placed in the graphite groove, and the FTO glass coated with cadmium sulfide in step (2) is placed on top of the groove and pressed down with a graphite block. A cadmium telluride active absorber layer with a thickness of about 3 μm is prepared by near-space sublimation. The temperature is set at 550℃ in the upper temperature zone and 700℃ in the lower temperature zone, and the gas pressure is set at 15 torr.

[0052] (4) Cadmium chloride treatment of cadmium telluride: Coat the surface of cadmium telluride with cadmium chloride methanol solution and dry it on a hot plate at 80°C. Then, invert the sample onto a graphite groove for heat treatment. The temperature is set at 400°C, the air pressure is 650 torr, and the time is 20 min.

[0053] (5) Spin-coating preparation of cuprous thiocyanate: First, wash away the remaining cadmium chloride on the surface of the cadmium telluride film after cadmium chloride treatment. Then, spin-coat the surface with 3 mg / ml of cuprous thiocyanate ammonia solution and spin dry. Finally, anneal at 250℃ for 20 min using a hot plate to diffuse copper to the front interface.

[0054] (6) Magnetron sputtering transparent electrode: The annealed product is placed in the magnetron sputtering chamber for sputtering coating. The gas pressure is stabilized at 0.3-1 Pa, the power is 70 W, the substrate is rotated (25 r / min), and the ITO transparent electrode is deposited by sputtering coating.

[0055] The copper concentration variation in the direction perpendicular to the plane obtained in this embodiment of the infrared narrowband optoelectronic device is as follows: Figure 4 As shown, it can be seen that through the annealing process in step (5), copper is fully diffused in the optoelectronic device and enriched on the FTO glass side.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 is that the electron transport layer is replaced with tin oxide prepared by chemical bath deposition, and the active absorber layer is replaced with CdSe prepared by thermal evaporation. 0.23 Te 0.77 The other steps and parameters remain unchanged, specifically:

[0058] (1) Use deionized water mixed with Micro-90 cleaning agent to ultrasonically clean the FTO glass.

[0059] (2) Electron transport layer preparation by chemical bath deposition: 0.1 M tin tetrachloride deionized water solution was used, and 0.2 M hydrogen peroxide solution was added to promote oxidation. The glass was placed vertically in the solution (the liquid level was 1-2 cm above the substrate), and 40 nm thick tin oxide was deposited at 80 °C with magnetic stirring at 150 rpm.

[0060] (3) Preparation of active absorber layer by thermal evaporation: The sample was fixed in the evaporation chamber for thermal evaporation. Using cadmium telluride and cadmium selenide evaporation sources, a CdSe layer with a thickness of about 3 μm was prepared at 250℃. 0.23 Te 0.77 The active absorber layer and EDS detection results are as follows: Figure 5 As shown.

[0061] (4) For CdSe 0.23 Te 0.77 Cadmium chloride treatment: in CdSe 0.23 Te 0.77 The surface was coated with cadmium chloride methanol solution and dried on a hot plate at 80°C. Then, the sample was inverted and placed on a graphite groove for heat treatment, with the temperature set at 400°C, the air pressure at 650 torr, and the time at 20 min.

[0062] (5) Spin-coating preparation of cuprous thiocyanate: First, wash away the remaining cadmium chloride on the surface of the cadmium telluride film after cadmium chloride treatment. Then, spin-coat the surface with 3 mg / ml of cuprous thiocyanate ammonia solution and spin dry. Finally, anneal at 250℃ for 20 min using a hot plate to diffuse copper to the front interface.

[0063] (6) Magnetron sputtering transparent electrode: The annealed product is placed in the magnetron sputtering chamber for sputtering coating. The gas pressure is stabilized at 0.3-1 Pa, the power is 70 W, the substrate is rotated (25 r / min), and the ITO transparent electrode is deposited by sputtering coating.

[0064] Example 3

[0065] The difference between this embodiment and Embodiment 1 is that the electron transport layer is zinc magnesium oxide and the active absorption layer is Cd. 1-x Zn xTe, the space transport layer is nickel oxide, and cuprous thiocyanate is spin-coated on the surface of the nickel oxide, specifically:

[0066] (1) Use deionized water mixed with Micro-90 cleaning agent to ultrasonically clean the FTO glass.

[0067] (2) Electron transport layer preparation by magnetron sputtering: FTO glass was placed in a magnetron sputtering chamber for sputtering deposition. The gas pressure was stabilized at 1~10 Pa, the power was 50 W, the substrate was rotated (25 r / min), and a 40 nm thick zinc magnesium oxide layer was deposited by sputtering.

[0068] (3) Preparation of active absorber layer by near-space sublimation method: The prepared Cd 1-x Zn x The Te source was placed in a graphite groove, and the FTO glass coated with zinc magnesium oxide in step (2) was placed on top of the groove and compacted with a graphite block. A Cd layer with a thickness of about 3 μm was prepared by near-space sublimation. 1-x Zn x The Te active absorber layer has an upper temperature range of 500℃ and a lower temperature range of 650℃, with a gas pressure of 15 torr. The value of x is 0, 0.05, 0.1, 0.2, 0.3, 0.4, or 1, and some Cd... 1-x Zn x The XRD results of Te are as follows Figure 6 As shown, the band gap can be adjusted by controlling the material of the active absorber layer.

[0069] (4) Regarding Cd 1-x Zn x Te is treated with cadmium chloride: in Cd 1-x Zn x The Te surface was coated with cadmium chloride methanol solution and dried on a hot plate at 80°C. Then, the sample was inverted and placed on a graphite groove for heat treatment, with the temperature set at 400°C, the air pressure at 650 torr, and the time at 20 min.

[0070] (5) Spin coating method to prepare nickel oxide as hole transport layer: First, wash away the remaining cadmium chloride on the surface of the cadmium telluride film after cadmium chloride treatment, then spin coat the surface with nickel oxide aqueous solution, then anneal the sample on a hot stage at 200℃ for 10 min, and finally treat the annealed sample with ultraviolet ozone for 5-10 s.

[0071] (6) Spin coating to prepare cuprous thiocyanate: Spin coat 3 mg / ml of cuprous thiocyanate ammonia solution onto the nickel oxide surface and spin dry. Finally, anneal at 250℃ for 20 min using a hot plate to diffuse copper to the front interface.

[0072] (7) Magnetron sputtering transparent electrode: The annealed product is placed in the magnetron sputtering chamber for sputtering coating. The gas pressure is stabilized at 0.3-1 Pa, the power is 70 W, the substrate is rotated (25 r / min), and the ITO transparent electrode is deposited by sputtering coating.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that the annealing temperature in step (5) is 200°C, while the other steps and parameters remain unchanged.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that step (5) was not annealed and doped, while the other steps and parameters remained unchanged.

[0077] Figure 7 The images show the spectral response test results of the infrared narrowband optoelectronic devices obtained in Example 1 and Comparative Examples 1-2. It can be seen that the infrared narrowband optoelectronic device obtained in Example 1 has excellent spectral selectivity, with the external quantum efficiency approaching 0 below wavelength 800 nm and a full width at half maximum (FWHM) of about 20 nm. However, the optoelectronic devices obtained in Comparative Example 1 (which had a lower annealing temperature and insufficient copper diffusion) and Comparative Example 2 (which did not undergo annealing and copper diffusion) have poor selectivity and higher external quantum efficiency below wavelength 800 nm.

[0078] Example 1 optoelectronic device with CdTe active absorption layer and CdSe active absorption layer. 0.23 Te 0.77 Example 2: The optoelectronic device and the active absorption layer are ZnTe and Cd, respectively. 0.95 Zn 0.05 Example 3 of Te involves spectral response testing of optoelectronic devices, such as... Figure 8 As shown, it can be seen that the response band can be adjusted in a wide range between 560 and 850 nm by regulating the active absorption layer.

[0079] In summary, this invention employs high-temperature annealing after the preparation of the cuprous thiocyanate layer, allowing copper to fully diffuse onto the FTO glass surface. This increases the P-type doping concentration of the active absorption layer, resulting in an extremely narrow built-in electric field (<400 nm). Ultraviolet and visible light are absorbed in the neutral region, making it difficult to penetrate to the space charge region and thus difficult for external circuits to collect. However, near-infrared spectroscopy has a deeper penetration depth, reaching the built-in electric field region. Under the influence of this built-in electric field, photogenerated electron / hole pairs can be efficiently separated and transported, thereby enabling the device to respond to a narrow spectrum. The active absorption layer uses Cd. 1-x Zn x Te or CdSe y Te 1-yBy adjusting the x and y values, the band gap of the active light-absorbing layer can be controlled, thereby achieving a wide range of adjustable response wavelengths between 560 and 850 nm.

[0080] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method of fabricating an infrared narrow-band optoelectronic device, characterized in that, The method comprises the following steps: S1, after preparing an electron transport layer on FTO glass, an active absorption layer is prepared on the electron transport layer; The material of the active absorption layer is Cd 1-x Zn x Te or CdSe y Te 1-y 0≤x≤1, 0≤y≤1 S2, after the active absorption layer is treated by cadmium chloride, a cuprous thiocyanate layer or a nickel oxide layer is prepared on the active absorption layer as a hole transport layer; When the hole transport layer is a nickel oxide layer, a cuprous thiocyanate layer is prepared on the hole transport layer; S3, annealing at 250±5℃ for 10-30min to diffuse copper to the interface of FTO glass; S4, a transparent electrode is prepared on the surface of the cuprous thiocyanate layer.

2. The method of fabricating an infrared narrow-band optoelectronic device of claim 1, wherein, The thickness of the electron transport layer is 30-60nm, the thickness of the active absorption layer is 1-6μm, and the thickness of the hole transport layer is 30-60nm.

3. The method of fabricating an infrared narrow-band optoelectronic device of claim 1, wherein, In S2, the cadmium chloride treatment is specifically as follows: after coating a cadmium chloride solution on the active absorption layer, heat treatment is performed at 390-420℃ and 600-700 torr for 20-60min.

4. The method of fabricating an infrared narrow-band optoelectronic device of claim 1, wherein, In S1, the material of the electron transport layer is cadmium sulfide, tin oxide or zinc magnesium oxide, and the electron transport layer is prepared by a radio frequency magnetron sputtering method, a chemical water bath deposition method or a spin coating method.

5. The method of fabricating an infrared narrow-band optoelectronic device of claim 1, wherein, In S1, the active absorption layer is prepared by a near-space sublimation method, a magnetron sputtering method, a thermal evaporation method or a chemical vapor deposition method.

6. The method of fabricating an infrared narrow-band optoelectronic device of claim 1, wherein, In S2, the cuprous thiocyanate layer and the nickel oxide layer are prepared by a magnetron sputtering method or a spin coating method.

7. The method of fabricating an infrared narrow-band optoelectronic device of claim 1, wherein, In S4, the material of the transparent electrode is ITO, and the transparent electrode is prepared by a magnetron sputtering method.

8. An infrared narrow-band optoelectronic device prepared by the preparation method in any one of claims 1-7.

9. The infrared narrow-band photovoltaic device of claim 8, wherein, The spectral half-width of the infrared narrow-band optoelectronic device is 20±10nm, and the light response EQE is greater than 30%.

10. The infrared narrow-band photovoltaic device of claim 8, wherein, The infrared narrow-band optoelectronic device can realize wide-range adjustment of the response wavelength between 560-850nm by adjusting the band gap of the active absorption layer.

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