Flexible silicon-based phototransistor and preparation method thereof

Abstract

The invention discloses a flexible silicon-based phototransistor and a preparation method thereof. The preparation method comprises the following steps: ultrasonically cleaning a silicon wafer; putting the cleaned silicon wafer into a potassium hydroxide solution, and etching in a water heating environment; depositing an Al: ZnO film on the back surface of the etched silicon wafer as an emitter of the bipolar phototransistor; depositing a zinc oxide film on the front surface of the etched silicon wafer as a collector electrode of the photoelectric transistor; and connecting the AZO on the back surface of the device with an ITO / PET substrate by using conductive silver paste, so that the device is transferred to the flexible substrate. According to the invention, based on an n-AZO / p-Si / n-ZnO heterojunction structure, by optimizing material selection and structural design, high-sensitivity photoresponse of the phototransistor in a wide spectrum range and effective regulation and control of mechanical strain are realized. The process is simple, flexibility is easy to achieve, the device is endowed with excellent photoelectric performance and environmental adaptability, and the method is suitable for research, development and application of flexible photoelectric detectors.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a flexible silicon-based phototransistor and a preparation method thereof. Background Art

[0002] In recent years, flexible electronic technology has become one of the important research directions in the field of electronic information. It has broad application prospects in the fields of wearable devices, flexible displays, biomedical sensors and intelligent robots. As the core component of flexible electronic technology, flexible optoelectronic devices have attracted much attention because they can achieve efficient conversion and processing of optoelectronic signals. Compared with traditional electronics, flexible electronics have greater flexibility and can adapt to different working environments to a certain extent, meet the deformation requirements of equipment, and have the characteristics of lightness, softness, thinness and transparency. These characteristics make it conformal to other things, greatly expanding the scope of application of electronic devices.

[0003] Among many optoelectronic devices, phototransistors have shown significant advantages in many application scenarios due to their unique dual functions of light response and signal amplification. Not only can they generate current under illumination, but they can also amplify signals through internal gain mechanisms, which makes them have broad application potential in the fields of light detection, light sensing, optical communications, and optoelectronic integration. However, current flexible phototransistors still face a series of challenges and limitations in terms of preparation materials, performance, stability, and compatibility with other technologies.

[0004] First, from the perspective of material preparation, traditional flexible phototransistors are mainly prepared based on inorganic semiconductor thin film materials or organic materials. Although inorganic semiconductor thin film materials such as silicon and germanium have high carrier mobility and good photoelectric properties, their flexibility is relatively poor and it is difficult to meet the deformation and bending requirements of flexible electronic devices. Although organic materials have good flexibility and processability, their photoelectric properties, stability and long-term reliability are still insufficient, which limits the performance of flexible phototransistors in practical applications.

[0005] Secondly, in terms of performance, key parameters of flexible phototransistors such as sensitivity, response speed, and gain are often affected by multiple factors such as preparation process, material selection, and device structure. How to improve these key parameters while maintaining flexibility is a major problem in the current research on flexible phototransistors. In addition, the stability of flexible phototransistors under long-term illumination or complex environments is also an important factor affecting their application prospects. How to improve the stability and durability of the device while ensuring performance is an issue that researchers need to explore in depth.

[0006] Furthermore, how to combine flexible devices with mature silicon-based processes is another key issue in the current research on flexible phototransistors. As the mainstream technology in the current semiconductor industry, silicon-based processes are highly mature and controllable. However, the preparation of flexible devices often involves complex processes such as material synthesis, thin film deposition, and micro-nano processing, which are incompatible with silicon-based processes. How to combine the preparation process of flexible devices with silicon-based processes to improve the controllability of the device preparation process and its compatibility with existing industrial technologies is a technical problem that current researchers need to focus on. Summary of the invention

[0007] The purpose of the present invention is to provide a flexible silicon-based phototransistor and a preparation method thereof, so as to solve the problems existing in the existing flexible phototransistors in terms of performance stability, process compatibility and preparation complexity. The present invention achieves high photoelectric response performance and excellent mechanical flexibility of the device by rationally designing the structure of the flexible silicon-based phototransistor and optimizing the preparation process. The flexible silicon-based phototransistor is composed of a flexible PET substrate, a silicon base, an emitter and a collector, and is designed based on a heterojunction structure to improve the photoelectric conversion efficiency. During the preparation process, a specific low-temperature process and flexible substrate transfer technology are used to ensure the integrity and functionality of the silicon-based material, while ensuring the stable working performance of the device in a bent state.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: A method for preparing a flexible silicon-based phototransistor comprises the following steps: 1) Use acetone, anhydrous ethanol and ultrapure water to ultrasonically clean the silicon wafer in sequence; 2) Place the cleaned silicon wafer into a potassium hydroxide solution and etch it in a heated water environment; 3) Depositing Al:ZnO thin film on the back of the etched silicon wafer as the emitter of the bipolar phototransistor; 4) Depositing a zinc oxide film on the front of the etched silicon wafer as the collector of the phototransistor; 5) Connect the AZO on the back of the device to the ITO / PET substrate using conductive silver paste to transfer the device to a flexible substrate.

[0009] A further improvement of the present invention is that in step 1), the silicon wafer used is a P-type doped silicon substrate.

[0010] A further improvement of the present invention is that in step 1), acetone, anhydrous ethanol and ultrapure water are used to ultrasonically clean the silicon wafer for 5 minutes respectively.

[0011] A further improvement of the present invention is that in step 2), the etching solution is a KOH solution with a mass fraction of 30%.

[0012] A further improvement of the present invention is that in step 2), when etching is performed in a water heating environment, heating is continued in a water environment at 85° C. and the etching time is 2 h.

[0013] A further improvement of the present invention is that in step 3), a radio frequency magnetron sputtering method is used, with a sputtering power of 95-105 W, an argon gas flow rate of 10 sccm, a sputtering pressure of 0.8-1.2 Pa, room temperature, pre-sputtering for 10 minutes, and formal sputtering for 25-30 minutes.

[0014] A further improvement of the present invention is that in step 4), a radio frequency magnetron sputtering method is used, with a sputtering power of 115-125 W, an oxygen flow rate of 5 sccm, an argon flow rate of 10 sccm, a sputtering pressure of 0.8-1.2 Pa, room temperature, pre-sputtering for 5 minutes, and formal sputtering for 30-35 minutes.

[0015] A further improvement of the present invention is that in step 5), silver paste is used to connect the phototransistor and the PET substrate.

[0016] A further improvement of the present invention is that step 5) further includes applying mechanical strain.

[0017] A flexible silicon-based photoelectric transistor is prepared by adopting the method for preparing a flexible silicon-based photoelectric transistor.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) Performance advantages: By optimizing the heterojunction interface characteristics and device structure design, the spectral response range and photoelectric conversion efficiency of the phototransistor are improved, and the flexible phototransistor is able to detect photons in a wide range of wavelengths from ultraviolet light to visible light to near-infrared light.

[0019] (2) Easy preparation: Using controllable low-temperature process and silicon-based transfer technology, the preparation process is simple, the film quality is stable, the thickness is controllable, and the production cost is reduced.

[0020] (3) Mechanical flexibility: The device can maintain stable photoelectric performance under multiple bending and deformation conditions, and the piezoelectric charge generated at the interface of the emitter junction and the collector junction by bending the device will significantly improve the photoresponse of the phototransistor. For 365 nm ultraviolet light, the photocurrent is 0.37 μA in the free state, and increases to 0.62 μA after applying a 1.5‰ tensile strain. Under a -1.5‰ compressive strain, the photocurrent increases to 1.95 μA, which is 6.32 times the tensile strain. For 648 nm visible light, under a -1.5‰ compressive strain, the photocurrent increases to a higher value, and under 830 nm near-infrared light, the photocurrent also shows a significant increase under compressive strain. These results show that with the increase of strain, the photocurrent is enhanced at different wavelengths, and the modulation effect of compressive strain is greater than that of tensile strain. (4) Strong compatibility: The preparation method is highly compatible with existing silicon-based microelectronics processes, facilitating large-scale integration and industrial applications.

[0021] In summary, the present invention focuses on the preparation of silicon-based flexible phototransistors, and proposes a method for preparing silicon-based flexible phototransistors based on the excellent electrical properties of silicon materials and their wide application advantages in the microelectronics industry. The present invention realizes the repeatable and low-cost manufacturing of high-performance flexible phototransistors, and promotes the application of flexible photoelectric devices in a wider range of fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a cross-sectional SEM image of a P-type silicon wafer that was etched in a 30% by mass potassium hydroxide solution in a water bath for 2 hours.

[0024] Figure 2 Schematic diagram of the overall structure of the phototransistor based on the flexible ITO / PET substrate.

[0025] Figure 3 This is a flow chart for the preparation of phototransistors based on flexible ITO / PET substrates.

[0026] Figure 4 Schematic diagram of the testing method of phototransistors based on flexible ITO / PET substrates.

[0027] Figure 5This is a schematic diagram of the test results of phototransistors based on flexible ITO / PET substrates subjected to different tensile and compressive strains under ultraviolet light irradiation.

[0028] Figure 6 This is a schematic diagram of the test results of phototransistors based on flexible ITO / PET substrates under visible light irradiation with different tensile and compressive strains.

[0029] Figure 7 This is a schematic diagram of the test results of phototransistors based on flexible ITO / PET substrates subjected to different tensile and compressive strains under near-infrared light irradiation. DETAILED DESCRIPTION

[0030] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0031] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0032] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0033] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0034] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0035] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] The present invention provides a method for preparing a flexible silicon-based phototransistor, and the specific steps are as follows: 1) Use acetone, anhydrous ethanol and ultrapure water to ultrasonically clean the silicon wafer for 5 minutes respectively; 2) Place the cleaned silicon wafer into KOH solution and etch in 85℃ water environment for 2 hours; 3) Depositing AZO thin film on the back of the etched silicon wafer by radio frequency magnetron sputtering as the emitter of the phototransistor; 4) Depositing ZnO thin film on the front side of the etched silicon wafer by radio frequency magnetron sputtering as the collector of the phototransistor; 5) Connect the AZO on the back of the phototransistor to the ITO / PET substrate using conductive silver paste to transfer the device to a flexible substrate.

[0037] 6) Clamp one side of the flexible substrate to one end of the metal frame 5, and then use the metal screw 2 of the three-dimensional translation stage 1 to push the other side of the substrate 6 to apply strain to the device. Unlike the hard substrate, the hard substrate directly applies strain to the c-axis of the zinc oxide nanowire, but the strain applied to the flexible substrate is indirectly applied to the c-axis by applying strain to the a-axis and the b-axis. The compressive strain applied to the a-axis and the b-axis is the tensile strain applied to the c-axis, and the tensile strain applied to the a-axis and the b-axis is the compressive strain applied to the c-axis; 7) Use a precision source meter to test the current-voltage characteristics of the device under different strains and different light intensities.

[0038] Embodiment 1: The device structure and preparation process of Example 1 are as follows: Figure 2 and Figure 3 As shown, the basic device structure is an n-AZO / p-Si / n-ZnO heterojunction phototransistor, the emitter uses a high electron concentration n-AZO film, the base uses an etched p-type silicon wafer, the collector uses an n-ZnO film, and the light source uses 365 nm ultraviolet light: 1) Use acetone, anhydrous ethanol and ultrapure water to ultrasonically clean for 5 minutes respectively; 2) Place the cleaned silicon wafer into KOH solution and etch in 85℃ water environment for 2 hours; 3) Deposit n-AZO thin film by radio frequency magnetron sputtering, with a sputtering power of 100 W, an argon gas flow rate of 10 sccm, a sputtering pressure of 1 Pa, room temperature, pre-sputtering for 10 minutes, and formal sputtering for 30 minutes; 4) Deposit n-ZnO thin film by RF magnetron sputtering, with a sputtering power of 120 W, an oxygen flow rate of 5 sccm, an argon flow rate of 10 sccm, a sputtering pressure of 1 Pa, room temperature, pre-sputtering for 5 minutes, and formal sputtering for 30 minutes; 5) Encapsulate with PDMS and then cure at 120°C for 20 minutes; 6) If Figure 4 As shown, during the test, one side of the flexible substrate is clamped at one end of a three-dimensional translation stage, and then the screw of another three-dimensional translation stage is used to push the other side of the substrate to apply strain to the device. The flexible substrate can apply tensile and compressive strain to the device through inward and outward concavities. It is important to note that the compressive strain applied to the substrate is a tensile strain for the ZnO nanowires, and the tensile strain applied to the substrate is a compressive strain for the ZnO nanowires. 7) Use a source meter to test the output characteristics of the device when different strains are applied under ultraviolet light. The bias voltage of the phototransistor is 5 V. Figure 5 The photocurrent represented in refers to the current of the device under different UV light intensities minus the current under dark field. Under fixed compressive strain, test the current output characteristics of the phototransistor under different light intensities, then increase the size of the compressive strain, and continue the above steps. The different light intensities are shown in the legend. After testing the compressive strain, release it again and apply tensile strain to repeat the above steps to continue testing.

[0039] Embodiment 2: The device structure and preparation process of Example 2 are the same as those of Example 1, except that the output characteristics of the phototransistor under visible light irradiation are studied: 1) Use acetone, anhydrous ethanol and ultrapure water to ultrasonically clean for 5 minutes respectively; 2) Place the cleaned silicon wafer into KOH solution and etch in 85℃ water environment for 2 hours; 3) Deposit n-AZO thin film by radio frequency magnetron sputtering, with a sputtering power of 100 W, an argon gas flow rate of 10 sccm, a sputtering pressure of 1 Pa, room temperature, pre-sputtering for 10 minutes, and formal sputtering for 30 minutes; 4) Deposit n-ZnO thin film by RF magnetron sputtering, with a sputtering power of 120 W, an oxygen flow rate of 5 sccm, an argon flow rate of 10 sccm, a sputtering pressure of 1 Pa, room temperature, pre-sputtering for 5 minutes, and formal sputtering for 30 minutes; 5) Encapsulate with PDMS and then cure at 120°C for 20 minutes; 6) If Figure 4 As shown, during the test, one side of the flexible substrate is clamped at one end of a three-dimensional translation stage, and then the screw of another three-dimensional translation stage is used to push the other side of the substrate to apply strain to the device. The flexible substrate can apply tensile and compressive strain to the device through inward and outward concavities. It is important to note that the compressive strain applied to the substrate is a tensile strain for the ZnO nanowires, and the tensile strain applied to the substrate is a compressive strain for the ZnO nanowires. 7) Use a source meter to test the output characteristics of the device when different strains are applied under visible light irradiation. The bias voltage of the phototransistor is 5 V. Figure 6 The photocurrent represented in refers to the current of the device under different visible light intensities minus the current under dark field. Under fixed compressive strain, test the current output characteristics of the phototransistor under different light intensities, then increase the size of the compressive strain, and continue the above steps. The different light intensities are shown in the legend. After testing the compressive strain, release it again and apply tensile strain to repeat the above steps to continue testing.

[0040] Embodiment 3: The device structure and preparation process of Example 3 are the same as those of Example 1 and Example 2, except that the output characteristics of the phototransistor under near-infrared light irradiation are studied: 1) Use acetone, anhydrous ethanol and ultrapure water to ultrasonically clean for 5 minutes respectively; 2) Place the cleaned silicon wafer into KOH solution and etch in 85℃ water environment for 2 hours; 3) Deposit n-AZO thin film by radio frequency magnetron sputtering, with a sputtering power of 100 W, an argon gas flow rate of 10 sccm, a sputtering pressure of 1 Pa, room temperature, pre-sputtering for 10 minutes, and formal sputtering for 30 minutes; 4) Deposit n-ZnO thin film by RF magnetron sputtering, with a sputtering power of 120 W, an oxygen flow rate of 5 sccm, an argon flow rate of 10 sccm, a sputtering pressure of 1 Pa, room temperature, pre-sputtering for 5 minutes, and formal sputtering for 30 minutes; 5) Encapsulate with PDMS and then cure at 120°C for 20 minutes; 6) If Figure 4 As shown, during the test, one side of the flexible substrate is clamped at one end of a three-dimensional translation stage, and then the screw of another three-dimensional translation stage is used to push the other side of the substrate to apply strain to the device. The flexible substrate can apply tensile and compressive strain to the device through inward and outward concavities. It is important to note that the compressive strain applied to the substrate is a tensile strain for the ZnO nanowires, and the tensile strain applied to the substrate is a compressive strain for the ZnO nanowires. 7) Use a source meter to test the output characteristics of the device when different strains are applied under visible light irradiation. The bias voltage of the phototransistor is 5 V. Figure 7 The photocurrent represented in refers to the current of the device under different visible light intensities minus the current under dark field. Under fixed compressive strain, test the current output characteristics of the phototransistor under different light intensities, then increase the size of the compressive strain, and continue the above steps. The different light intensities are shown in the legend. After testing the compressive strain, release it again and apply tensile strain to repeat the above steps to continue testing.

[0041] This paper proposes an innovative n-AZO / p-Si / n-ZnO heterojunction structure, which shows excellent performance and wide application potential in the field of phototransistors. By carefully optimizing material selection and structural design, we have successfully achieved highly sensitive photoresponse of phototransistors in a wide spectral range, while achieving effective regulation of mechanical strain. This breakthrough not only provides new ideas for the research and development of flexible photodetection devices, but also provides strong support for performance improvement and environmental adaptability enhancement in practical applications.

[0042] In terms of material selection, the present invention uses n-type aluminum-doped zinc oxide (n-AZO), p-type silicon (p-Si) and n-type zinc oxide (n-ZnO) as the components of the heterojunction structure. As a transparent conductive oxide, n-AZO has excellent conductivity and light transmittance, and can effectively improve the light absorption efficiency and charge transfer capacity of phototransistors. As a semiconductor material, p-Si has a mature preparation process and stable electrical properties, and is an ideal choice for constructing high-performance heterojunction structures. Due to its good piezoelectric effect and photoelectric properties, n-ZnO plays an important role in mechanical strain regulation and light response.

[0043] In terms of structural design, the present invention achieves effective regulation of the internal electric field of the heterojunction structure and optimization of the charge transfer path by precisely controlling the thickness, doping concentration and interface quality of each layer of material. This structural design not only improves the photoelectric conversion efficiency of the phototransistor, but also enhances its sensitivity to mechanical strain and response speed.

[0044] The preparation method is simple and easy to achieve flexibility. By adopting mature thin film preparation technologies such as solution method and vapor deposition, we can easily prepare high-quality n-AZO / p-Si / n-ZnO heterojunction structures on flexible substrates. This flexible preparation process not only reduces production costs, but also improves the integrability and application range of devices.

[0045] In addition, the device also exhibits excellent optoelectronic performance and environmental adaptability. In a wide spectral range, the phototransistor exhibits highly sensitive light response characteristics, enabling rapid response and accurate detection of light of different wavelengths. At the same time, through effective regulation of mechanical strain, the device can also maintain stable performance output in complex environments.

[0046] In summary, the n-AZO / p-Si / n-ZnO heterojunction structure phototransistor proposed in the present invention has shown significant advantages in material selection, structural design, preparation process and performance. This innovative achievement not only provides new ideas and directions for the research and development of flexible photodetection devices, but also provides strong support for performance improvement and environmental adaptability enhancement in practical applications.

[0047] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0048] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a flexible silicon-based phototransistor, characterized in that: The following steps are involved: 1) Use acetone, anhydrous ethanol and ultrapure water to ultrasonically clean the silicon wafer in sequence; 2) Place the cleaned silicon wafer into a potassium hydroxide solution and etch it in a heated water environment; 3) Depositing Al:ZnO thin film on the back of the etched silicon wafer as the emitter of the bipolar phototransistor; 4) Depositing a zinc oxide film on the front of the etched silicon wafer as the collector of the phototransistor; 5) Connect the AZO on the back of the device to the ITO / PET substrate using conductive silver paste to transfer the device to a flexible substrate.

2. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 1), the silicon wafer used is a P-type doped silicon substrate.

3. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 1), acetone, anhydrous ethanol and ultrapure water are used to ultrasonically clean the silicon wafer for 5 minutes respectively.

4. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 2), the etching solution is a KOH solution with a mass fraction of 30%.

5. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 2), when etching is performed in a water heating environment, continuous heating is performed in a water environment at 85°C, and the etching time is 2 h.

6. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 3), a radio frequency magnetron sputtering method is used, with a sputtering power of 95-105 W, an argon gas flow rate of 10 sccm, a sputtering pressure of 0.8-1.2 Pa, room temperature, pre-sputtering for 10 minutes, and formal sputtering for 25-30 minutes.

7. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 4), a radio frequency magnetron sputtering method is used, with a sputtering power of 115-125 W, an oxygen flow rate of 5 sccm, an argon flow rate of 10 sccm, a sputtering pressure of 0.8-1.2 Pa, room temperature, pre-sputtering for 5 minutes, and formal sputtering for 30-35 minutes.

8. The method for preparing a flexible silicon-based phototransistor according to claim 1, characterized in that: In step 5), the phototransistor and the PET substrate are connected using silver paste.

9. The method for preparing a flexible silicon-based phototransistor according to claim 8, characterized in that: Step 5) also includes applying mechanical strain.

10. A flexible silicon-based phototransistor, characterized in that: The flexible silicon-based phototransistor is prepared by the method for preparing the flexible silicon-based phototransistor according to any one of claims 1 to 9.

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