Spectrum-adjustable photoelectric detector and preparation method thereof
By forming silicon oxide layers and perovskite layers of different thicknesses on a silicon substrate, the risks of eavesdropping and interference in optical communication by photodetectors are solved, enabling multispectral identification and detection, and enhancing the security of optical encrypted communication and the miniaturization and integration of equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU UNIV
- Filing Date
- 2025-12-31
- Publication Date
- 2026-05-08
AI Technical Summary
Existing photodetectors pose risks of eavesdropping and interference in optical communications, and it is difficult to simultaneously meet the requirements of miniaturization, integration, and intelligence of equipment with multispectral detection. In particular, the poor short-wavelength sensitivity of silicon materials and the non-absorption problem of perovskites at long wavelengths have not been effectively solved.
By controlling the ultraviolet ozone treatment time in different regions of the silicon substrate surface, silicon oxide layers of varying thicknesses are formed on the silicon substrate. Combined with a perovskite layer and an air transport layer, a spectrally tunable photodetector is fabricated, enabling control over the spectral response range.
It achieves multispectral recognition and detection, increases the difficulty of decrypting optical encrypted communication, and the preparation process does not require solvents, making it suitable for miniaturized and integrated optical communication systems.
Smart Images
Figure CN122003075A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photodetector technology, and more specifically to a spectrally tunable photodetector and its fabrication method. Background Technology
[0002] Optical communication technology boasts advantages such as long transmission distance, high speed, large information capacity, and low cost, leading to its widespread application in modern communication networks, including long-distance communication, local area networks (LANs), and data center interconnection. Furthermore, optical signals are inherently immune to electromagnetic interference, making them particularly suitable for operation in high electromagnetic noise environments, giving them an irreplaceable advantage in critical scenarios. However, optical transmission also carries the risk of eavesdropping and interference, potentially leading to privacy breaches. Therefore, new encryption strategies must be developed to prevent data interception and unauthorized decryption.
[0003] Physical layer encryption, leveraging inherent material properties, has emerged as a promising alternative. Researchers have developed photodetectors with specific responses (bipolar, dual-frequency, narrowband, broadband, or special response waveforms) for encrypted optical communications, based on the composition, morphology, and device structure of thin films. Among these, multispectral detection, by expanding the key space into a multidimensional domain, exponentially increases decryption complexity. However, this typically requires assembling composite devices, conflicting with the principles of device miniaturization, integration, and intelligence.
[0004] In the current optoelectronic field, silicon materials maintain a dominant position due to their mature mass production capabilities, high integration compatibility, and excellent performance. Solution-processed metal halide perovskites have great potential due to their excellent optoelectronic properties and easy manufacturing processes, especially since they can be prepared at room temperature under certain conditions, thus reducing the slow coating speed and high energy consumption of the annealing process. Combining perovskites with silicon compensates for silicon's poor short-wavelength sensitivity and perovskites' non-absorption at long wavelengths, thereby greatly improving detection capability, response speed, and other parameters.
[0005] Furthermore, perovskite thin films can be directly deposited on silicon wafers, ensuring compatibility with existing silicon-based production lines and facilitating low-cost miniaturization and integration. Therefore, developing and optimizing suitable perovskite / silicon structures is essential for future commercial applications. Summary of the Invention
[0006] This invention addresses the shortcomings of existing technologies by providing a spectrally tunable photodetector and its fabrication method. By controlling the ultraviolet ozone treatment time of different regions on the surface of a silicon substrate, silicon oxide layers of varying thicknesses are formed on the silicon substrate, thereby achieving spectral tuning and applying it to encrypted optical communication. The method avoids the use of solvents in the fabrication of silicon oxide layers of different thicknesses and does not affect adjacent regions, showing great potential in the fabrication of array devices in micro-regions, which is beneficial for future industrial applications.
[0007] To address the aforementioned technical problems, the first aspect of this invention provides a method for fabricating a spectrally tunable photodetector, comprising the following steps:
[0008] S1, Provides a silicon substrate;
[0009] S2. Adjust the ultraviolet ozone treatment time of different areas on the surface of the silicon substrate to form silicon oxide layers of different thicknesses in different areas on the silicon substrate;
[0010] S3. Spin-coat the perovskite precursor solution onto the side of the silicon substrate with a silicon oxide layer, and place it in air to form a methylamine lead iodide perovskite layer.
[0011] S4. Spin-coat the air transport layer precursor solution onto the surface of the methylamine lead iodide perovskite layer and place it in nitrogen to form an air transport layer.
[0012] S5. Magnetron sputtering of the top electrode yields the spectrally tunable photodetector.
[0013] This invention forms silicon oxide layers of varying thicknesses in different regions of a silicon substrate by adjusting the ultraviolet ozone treatment time on the substrate surface. By controlling the thickness of the silicon oxide layer, the spectral response range can be adjusted, thereby enabling multispectral identification and detection. When applied to optical encryption communication, the difficulty of decryption increases because the intensity and wavelength of light can be arbitrarily combined.
[0014] The method of this invention allows for the preparation of silicon oxide layers of different thicknesses without the use of solvents, and does not affect the direct integration of photoelectric arrays on the silicon substrate surface in adjacent areas, enabling direct collection of optical signals. These features provide a more practical approach for realizing miniaturized, integrated, and intelligent encrypted optical communication systems. The preparation process is simple, and the photodetector exhibits excellent performance.
[0015] Furthermore, step S1 also includes a step of immersing the silicon substrate in a hydrofluoric acid solution for cleaning. Preferably, the hydrofluoric acid solution is an aqueous solution of hydrofluoric acid, and the silicon substrate is immersed in the hydrofluoric acid solution for 15-30 minutes to remove the naturally formed silicon oxide layer on the surface of the silicon substrate and improve accuracy.
[0016] Furthermore, in S2, the process of adjusting the ultraviolet ozone treatment time in different regions of the silicon substrate surface to form silicon oxide layers of varying thicknesses in different regions on the silicon substrate specifically involves:
[0017] (1) Cover the silicon substrate with polydimethylsiloxane (to isolate the silicon substrate from oxygen).
[0018] (2) Remove polydimethylsiloxane from a specified area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for treatment to oxidize the silicon and form a silicon oxide layer;
[0019] (3) Remove polydimethylsiloxane from another designated area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for treatment. The silicon is oxidized to form a silicon oxide layer (the newly exposed silicon substrate reacts to generate silicon oxide, and the previously exposed silicon substrate continues to react to generate silicon oxide. Under the condition that the time does not exceed a certain period, the degree of silicon oxidation is proportional to the oxidation time. By controlling the ultraviolet oxidation treatment time, silicon oxide of different thicknesses can be obtained).
[0020] (4) Repeat step (3) 0-5 times;
[0021] (5) Remove the remaining polydimethylsiloxane from the surface of the silicon substrate to expose the silicon substrate.
[0022] Furthermore, in step (1), covering the silicon substrate with polydimethylsiloxane specifically involves: mixing polydimethylsiloxane and a curing agent and then coating it onto the surface of the silicon substrate, followed by heat treatment at 140-160°C.
[0023] Furthermore, the designated region described in steps (2) and (3) independently comprises several array-arranged unit regions.
[0024] Furthermore, the time for treatment with the ultraviolet ozone generator described in steps (2) and (3) is 1-10 minutes.
[0025] Furthermore, in S3, the concentration of the perovskite precursor (methylamine lead iodine precursor) solution is 1-1.8 mM; preferably, the solvent for the perovskite precursor solution is a mixed solvent of ethylamine and acetonitrile.
[0026] Furthermore, in S4, the solute of the air transport layer precursor solution is poly(3-hexylthiophene) with a concentration of 10 mg / mL; preferably, the solvent of the air transport layer precursor solution is chlorobenzene.
[0027] Furthermore, the top electrode is an indium zinc oxide transparent electrode, and the thickness of the top electrode is 200-300 nm.
[0028] Furthermore, in S5, the magnetron sputtering top electrode is specifically: a silicon substrate that can rotate around a central axis is fixed in the magnetron sputtering cavity, and an array of electrodes is sputtered on the surface of the air transport layer with the assistance of a mask.
[0029] Furthermore, the plane containing the silicon substrate is perpendicular to the sputtering direction, the silicon substrate rotates around the central axis at a speed of 0.5-5 r / s, and the sputtering conditions are: gas pressure 0.1-1 Pa, power 30-80 W, and time 10-40 min.
[0030] The second aspect of the present invention provides a spectrally tunable photodetector prepared by the preparation method described in the first aspect.
[0031] The beneficial effects of this invention are:
[0032] This invention forms silicon oxide layers of varying thicknesses in different regions of a silicon substrate by adjusting the ultraviolet ozone treatment time on the substrate surface. By controlling the thickness of the silicon oxide layer, the spectral response range can be adjusted, thereby enabling multispectral identification and detection. When applied to optical encryption communication, the difficulty of decryption increases because the intensity and wavelength of light can be arbitrarily combined.
[0033] The method of this invention allows for the preparation of silicon oxide layers of different thicknesses without the use of solvents, and does not affect the direct integration of photoelectric arrays on the silicon substrate surface in adjacent areas, enabling direct collection of optical signals. These features provide a more practical approach for realizing miniaturized, integrated, and intelligent encrypted optical communication systems. The preparation process is simple, and the photodetector exhibits excellent performance. Attached Figure Description
[0034] 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.
[0035] Figure 1 This is a flowchart of the fabrication method of the spectrally tunable photodetector of the present invention;
[0036] Figure 2 This is a schematic diagram of the magnetron sputtering top electrode of the present invention;
[0037] Figure 3 The wavelength range that the photodetector in Embodiment 1 of the present invention can modulate the response of;
[0038] Figure 4 This refers to the wavelength range of the modulation response of the photodetector in Comparative Example 4 of the present invention. Detailed Implementation
[0039] 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.
[0040] refer to Figure 1 This embodiment relates to a method for fabricating a spectrally tunable photodetector, comprising the following steps:
[0041] S1, Provides a silicon substrate;
[0042] S2. Adjust the ultraviolet ozone treatment time of different areas on the surface of the silicon substrate to form silicon oxide layers of different thicknesses in different areas on the silicon substrate;
[0043] S3. Spin-coat the perovskite precursor solution onto the side of the silicon substrate with a silicon oxide layer, and place it in air to form a methylamine lead iodide perovskite layer.
[0044] S4. Spin-coat the air transport layer precursor (poly-3-hexylthiophene) solution onto the surface of the methylamine lead iodide perovskite layer and place it in nitrogen to form an air transport layer.
[0045] S5. Magnetron sputtering of the top electrode (indium zinc oxide transparent electrode) to obtain the spectrally tunable photodetector.
[0046] This embodiment forms silicon oxide layers of varying thicknesses on a silicon substrate by controlling the ultraviolet ozone treatment time in different regions of the substrate. By controlling the thickness of the silicon oxide layer, the spectral response range can be adjusted, enabling multispectral identification and detection. Applied to optical encrypted communication, where the arbitrary combination of light intensity and wavelength increases the difficulty of decryption, this embodiment demonstrates that the fabrication of silicon oxide layers of varying thicknesses requires no solvent and does not affect the direct integration of photoelectric arrays on adjacent regions of the silicon substrate surface for direct collection of optical signals. These features provide a more practical approach to realizing miniaturized, integrated, and intelligent encrypted optical communication systems. The fabrication process is simple, and the photodetector exhibits excellent performance.
[0047] In a preferred embodiment, step S1 further includes a step of immersing the silicon substrate in a hydrofluoric acid solution for cleaning. Preferably, the hydrofluoric acid solution is an aqueous solution of hydrofluoric acid, and the silicon substrate is immersed in the hydrofluoric acid solution for 15-30 minutes to remove the naturally formed silicon oxide layer on the surface of the silicon substrate, thereby improving accuracy.
[0048] In a preferred embodiment, S2, the process of adjusting the ultraviolet ozone treatment time in different regions of the silicon substrate surface to form silicon oxide layers of different thicknesses in each region on the silicon substrate specifically involves:
[0049] (1) After mixing polydimethylsiloxane and curing agent, the mixture is coated onto the surface of a silicon substrate and then heat-treated at 140-160℃;
[0050] (2) Remove polydimethylsiloxane from a specified area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for treatment to oxidize the silicon and form a silicon oxide layer;
[0051] (3) Remove polydimethylsiloxane from another designated area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for treatment. The silicon is oxidized to form a silicon oxide layer (the newly exposed silicon substrate reacts to generate silicon oxide, and the previously exposed silicon substrate continues to react to generate silicon oxide. Under the condition that the time does not exceed a certain period, the degree of silicon oxidation is proportional to the oxidation time. By controlling the ultraviolet oxidation treatment time, silicon oxide of different thicknesses can be obtained).
[0052] (4) Repeat step (3) 0-5 times;
[0053] (5) Remove the remaining polydimethylsiloxane from the surface of the silicon substrate to expose the silicon substrate.
[0054] Preferably, the designated area in steps (2) and (3) independently comprises several array-arranged unit areas; the treatment time in the ultraviolet ozone generator is 1-10 minutes.
[0055] In a preferred embodiment, in S3, the concentration of the perovskite precursor (methylamine lead iodine precursor) solution is 1-1.8 mM; preferably, the solvent of the perovskite precursor solution is a mixed solvent of ethylamine and acetonitrile.
[0056] In a preferred embodiment, in S4, the concentration of the air transport layer precursor solution is 10 mg / mL; preferably, the solvent of the air transport layer precursor solution is chlorobenzene.
[0057] In a preferred embodiment, in S5, the magnetron sputtering top electrode specifically refers to: [reference] Figure 2 A silicon substrate is fixed in a magnetron sputtering cavity, rotatable around a central axis. With the assistance of a mask, an array of electrodes is sputtered on the surface of an air transport layer. The plane containing the silicon substrate is perpendicular to the sputtering direction. The silicon substrate rotates around the central axis at a speed of 0.5-5 r / s. The sputtering conditions are: air pressure 0.1-1 Pa, power 30-80 W, and time 10-40 min. The thickness of the top electrode is 200-300 nm.
[0058] Another embodiment provides a spectrally tunable photodetector prepared by the preparation method described in the above embodiments.
[0059] Example 1
[0060] This embodiment relates to a method for fabricating a spectrally tunable photodetector, comprising the following steps:
[0061] (1) After diluting deionized water and hydrofluoric acid at a volume ratio of 5:1, immerse the silicon substrate in the solution for 20 minutes to completely wash away the silicon oxide naturally formed on the surface of the silicon substrate.
[0062] (2) Polydimethylsiloxane and curing agent (platinum(II)2-ethylhexadienoate) were mixed at a mass ratio of 10:1 and coated onto the surface of a silicon substrate, and then heated at 150°C for 10 min.
[0063] (3) Remove polydimethylsiloxane from the first designated area on the surface of the silicon substrate to expose the silicon substrate and place it in a UV ozone generator for 5 min; then remove polydimethylsiloxane from the second designated area to expose the silicon substrate and place it in a UV ozone generator for 2 min; then remove polydimethylsiloxane from the third designated area to expose the silicon substrate and place it in a UV ozone generator for 3 min; remove the remaining polydimethylsiloxane to obtain silicon substrates with different silicon oxide layer thicknesses in areas that have been treated with UV ozone for 10 min, 5 min, 3 min, and 0 min.
[0064] (3) A 1.8 mM methylamine lead iodide precursor (methylamine iodide to lead iodide molar ratio 1:1) solution (solvent: ethylamine and acetonitrile with a volume ratio of 3:2) was spin-coated onto the side surface of the silicon substrate with a silicon oxide layer and placed in air to form a methylamine lead iodide perovskite layer.
[0065] (4) Spin-coat a 10 mg / mL poly(3-hexylthiophene) solution (solvent chlorobenzene) onto the surface of the methylamine lead iodide perovskite layer and place it in nitrogen to form a hole transport layer.
[0066] (5) Fix the silicon substrate in a magnetron sputtering cavity that can rotate around the central axis, and sputter an array of indium zinc oxide electrodes on the surface of the air transport layer with the assistance of a mask; the plane where the silicon substrate is located is perpendicular to the sputtering direction, the silicon substrate rotates around the central axis at a speed of 1 r / s, and the sputtering conditions are: air pressure 0.2 Pa, power 50 W, time 20 min. Figure 3 The wavelength range of the modulation response of the photodetector in Example 1 is shown. It can be seen that the detector can distinguish light in four ranges: 300-460nm, 460-600nm, 600-800nm, and 800-1100nm by obtaining silicon oxide layers of different thicknesses with different ultraviolet ozone treatment times.
[0067] Comparative Example 1
[0068] The difference between this comparative example and Example 1 is that step (3) involves removing polydimethylsiloxane from the first designated area on the surface of the silicon substrate to expose the silicon substrate, and then treating it with an ultraviolet ozone generator for 10 minutes; removing the remaining polydimethylsiloxane to obtain silicon substrates with different silicon oxide layer thicknesses in areas treated with a cumulative ultraviolet ozone for 10 minutes and 0 minutes. Test results of the detector show that the spectral response range can only be modulated between two states: 300-800 nm and 800-1100 nm, and cannot reach the four ranges of 300-460 nm, 460-600 nm, 600-800 nm, and 800-1100 nm as in Example 1.
[0069] Comparative Example 2
[0070] The difference between this comparative example and Example 1 is that step (3) is as follows: remove polydimethylsiloxane from the first designated area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for 5 minutes; remove the remaining polydimethylsiloxane to obtain silicon substrates with different silicon oxide layer thicknesses in areas that have been treated with ultraviolet ozone for 5 minutes and 0 minutes. The test results of the detector show that the spectral response range can only be modulated between two states: 600-800nm and 800-1100nm, and cannot reach the four ranges of 300-460nm, 460-600nm, 600-800nm, and 800-1100nm of Example 1.
[0071] Comparative Example 3
[0072] The difference between this comparative example and Example 1 is that step (5) involves magnetron sputtering to prepare the indium tin oxide array electrode, while other steps and parameters remain unchanged. Test results of the detector show that regardless of the silicon oxide thickness, the response range remains a single state of 300-1100 nm, failing to reach the four ranges of 300-460 nm, 460-600 nm, 600-800 nm, and 800-1100 nm found in Example 1.
[0073] Comparative Example 4
[0074] The difference between this comparative example and Example 1 is that step (3) involves spin-coating to prepare a formamidinium lead iodide perovskite layer, while other steps and parameters remain unchanged. Figure 4 As shown in the wavelength range of the photodetector modulation response in Comparative Example 4, it can be seen that regardless of the change in silicon oxide thickness, the response range is a single state of 300-1100nm, which cannot reach the four ranges of 300-460nm, 460-600nm, 600-800nm, and 800-1100nm of the embodiment.
[0075] The response range of the detectors in Comparative Examples 3-4 could not be changed with the thickness of the silicon oxide, resulting in the device lacking multispectral recognition capability. This is because the work function of the indium tin oxide electrode does not match that of the perovskite. Formamidinium lead iodide perovskite can only be prepared using traditional annealing methods, leading to an excessively thin perovskite layer. As a result, most of the light can penetrate the perovskite to reach the silicon layer, thus responding to light in the 300-1100nm range.
[0076] In summary, this invention forms silicon oxide layers of varying thicknesses on a silicon substrate by controlling the ultraviolet ozone treatment time in different regions of the substrate. By controlling the thickness of the silicon oxide layer, the spectral response range can be adjusted, thereby enabling multispectral identification and detection. Applied to optical encryption communication, where the arbitrary combination of light intensity and wavelength increases the difficulty of decryption, this invention allows for the preparation of silicon oxide layers of different thicknesses without the need for solvents and does not affect the direct integration of photoelectric arrays on adjacent regions of the silicon substrate surface for direct collection of optical signals. These features provide a more practical approach to realizing miniaturized, integrated, and intelligent encrypted optical communication systems. The fabrication process is simple, and the photodetector exhibits excellent performance.
[0077] 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 for fabricating a spectrally tunable photodetector, characterized in that, Includes the following steps: S1, Provides a silicon substrate; S2. Adjust the ultraviolet ozone treatment time of different areas on the surface of the silicon substrate to form silicon oxide layers of different thicknesses in different areas on the silicon substrate; S3. Spin-coat the perovskite precursor solution onto the side of the silicon substrate with a silicon oxide layer, and place it in air to form a methylamine lead iodide perovskite layer. S4. Spin-coat the air transport layer precursor solution onto the surface of the methylamine lead iodide perovskite layer and place it in nitrogen to form an air transport layer. S5. Magnetron sputtering of the top electrode yields the spectrally tunable photodetector.
2. The method for fabricating a spectrally tunable photodetector as described in claim 1, characterized in that, S1 also includes the step of immersing the silicon substrate in a hydrofluoric acid solution for cleaning.
3. The method for fabricating a spectrally tunable photodetector as described in claim 1, characterized in that, In S2, the process of adjusting the ultraviolet ozone treatment time in different regions of the silicon substrate surface to form silicon oxide layers of different thicknesses in each region on the silicon substrate specifically involves: (1) Coating a silicon substrate with polydimethylsiloxane; (2) Remove polydimethylsiloxane from a specified area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for treatment to oxidize the silicon and form a silicon oxide layer; (3) Remove polydimethylsiloxane from another designated area on the surface of the silicon substrate to expose the silicon substrate, and place it in an ultraviolet ozone generator for treatment, where silicon is oxidized to form a silicon oxide layer; (4) Repeat step (3) 0-5 times; (5) Remove the remaining polydimethylsiloxane from the surface of the silicon substrate to expose the silicon substrate.
4. The method for fabricating a spectrally tunable photodetector as described in claim 3, characterized in that, In step (1), covering the silicon substrate with polydimethylsiloxane specifically involves mixing polydimethylsiloxane and a curing agent and then coating the mixture onto the surface of the silicon substrate, followed by heat treatment at 140-160°C.
5. The method for fabricating a spectrally tunable photodetector as described in claim 3, characterized in that, The designated area described in steps (2) and (3) consists of several array-arranged unit areas.
6. The method for fabricating a spectrally tunable photodetector as described in claim 1, characterized in that, In S3, the concentration of the perovskite precursor solution is 1-1.8 mM.
7. The method for fabricating a spectrally tunable photodetector as described in claim 1, characterized in that, In S4, the solute in the air transport layer precursor solution is poly(3-hexylthiophene) with a concentration of 10 mg / mL.
8. The method for fabricating a spectrally tunable photodetector as described in claim 1, characterized in that, In S5, the magnetron sputtering top electrode is specifically: a silicon substrate that can rotate around a central axis is fixed in the magnetron sputtering cavity, and an array of electrodes is sputtered on the surface of the air transport layer with the assistance of a mask.
9. The method for fabricating a spectrally tunable photodetector as described in claim 1, characterized in that, The plane containing the silicon substrate is perpendicular to the sputtering direction. The silicon substrate rotates around the central axis at a speed of 0.5-5 r / s. The sputtering conditions are: gas pressure 0.1-1 Pa, power 30-80 W, and time 10-40 min.
10. A spectrally tunable photodetector prepared by the preparation method according to claims 1-9.