A positive and negative bidirectional light-responsive transistor and its preparation method

Abstract

The present invention provides a positive and negative bidirectional photoresponsive transistor and a method for fabricating the same. The transistor comprises a heavily doped conductive silicon substrate on which is deposited a silicon dioxide dielectric layer, a first photoresponsive structure disposed on the silicon dioxide dielectric layer, and a second photoresponsive structure disposed on the first photoresponsive structure. The phototransistor of the present invention can distinguish between ultraviolet and infrared light through bidirectional photoresponsiveness, producing a positive response to ultraviolet light and a negative response to infrared light. Compared to existing low-dimensional materials or circuit designs, it has low cost and a simple structure. Furthermore, the fabrication method utilizes a solution process to produce an ultrathin indium oxide layer and an organic film, resulting in a lower process cost than conventional vacuum equipment fabrication methods.

Description

Technical Field

[0001] The present invention relates to the technical field of phototransistors, and in particular to a positive and negative bidirectional light-responsive transistor and a preparation method thereof. Background Art

[0002] Phototransistors based on thin-film transistors (TFTs) with a three-terminal device configuration have attracted extensive research and attention due to their gate-tunable photoresponse, intrinsic signal amplification, and feasibility of monolithic integration. However, the inherent characteristics of the photoelectric effect mean that most phototransistors can only generate positive photocurrent and are sensitive only to the intensity of the input light rather than its wavelength. Phototransistors with positive photoresponse have made great progress, but the characteristics of negative or inhibitory photoresponse are also indispensable for building fully light-driven optoelectronic systems, but current progress in this area is very limited.

[0003] Current research has explored various nanomaterials, structures, and circuit designs to achieve bidirectional photoresponse. For example, bidirectional photoresponse has been achieved by exploiting surface defects in low-dimensional materials, van der Waals heterojunctions, and voltage divider designs, and has been applied to convolution operations and weight adjustment in artificial neural networks. Despite these advances, the complex synthesis of low-dimensional materials, process incompatibilities, and difficulties in large-scale fabrication have hindered the current ability to fabricate bidirectional photoelectric devices on a large scale. Summary of the Invention

[0004] In order to solve the problems existing in the background technology, the present invention proposes a positive and negative bidirectional light-responsive transistor.

[0005] A positive and negative bidirectional light-responsive transistor comprises a heavily doped conductive silicon substrate on which a silicon dioxide dielectric layer is deposited, a first light-responsive structure is arranged on the silicon dioxide dielectric layer, and a second light-responsive structure is arranged on the first light-responsive structure.

[0006] Based on the above, the first light-responsive structure includes an N-type semiconductor channel deposited on the silicon dioxide dielectric layer and source-drain electrodes arranged on the N-type semiconductor channel, and the source-drain electrodes form a Schottky junction with the N-type semiconductor channel.

[0007] Based on the above, the second light-responsive structure is an organic layer having the ability to absorb light of a certain wavelength.

[0008] Based on the above, the N-type semiconductor channel is an indium oxide channel.

[0009] Based on the above, the source and drain electrodes are gold electrodes.

[0010] Based on the above, the thickness of the silicon dioxide dielectric layer is 100 nm, the thickness of the N-type semiconductor layer is 5-10 nm, and the thickness of the source-drain electrode layer is 30-50 nm.

[0011] Based on the above, the organic layer is an organic polymer layer or a small molecule layer having near-infrared absorption capability.

[0012] A method for preparing a positive and negative bidirectional light-responsive transistor, comprising the steps of:

[0013] S01. Preparing an indium oxide precursor solution;

[0014] S02. Cleaning the heavily doped conductive silicon substrate, depositing a silicon dioxide dielectric layer on the heavily doped conductive silicon substrate, and then cleaning the silicon dioxide dielectric layer;

[0015] S03 spin-coating an indium oxide precursor solution on the silicon dioxide dielectric layer, and preparing an indium oxide channel by photolithography or optical patterning;

[0016] S04 depositing a source and drain electrode made of metallic gold on the indium oxide semiconductor layer to form a Schottky contact indium oxide thin film transistor;

[0017] S05. After subjecting the indium oxide thin film transistor to ultraviolet ozone treatment to make its surface hydrophilic, organic matter is dynamically spin-coated on the indium oxide thin film transistor to form a bidirectional light-responsive transistor.

[0018] Based on the above, step S03 includes:

[0019] S031. The silicon dioxide dielectric layer was subjected to UV ozone treatment for 10 min to make its surface hydrophilic;

[0020] S032. The indium nitrate precursor solution is spin-coated on the silicon dioxide dielectric layer and pre-baked at 100°C to form a sol-gel film;

[0021] S033. Cover the film with a mask and irradiate it under deep ultraviolet light for 10 minutes;

[0022] S034. The sample is etched, and the unexposed area is dissolved by the etching solution, leaving the exposed portion of the film;

[0023] S035. The sample was washed with deionized water and dried with nitrogen, and the patterned indium oxide film was annealed at 300°C for 1 h.

[0024] Based on the above, step S05 includes:

[0025] S051. The organic compound is an organic polymer or small molecule with near-infrared absorption capability;

[0026] S052. UV-ozone treatment of Schottky indium oxide thin film transistors for 30 seconds to make the surface hydrophilic;

[0027] S053. Dynamically spin-coat the organic solution and anneal at 100°C for 5 minutes.

[0028] The present invention has outstanding substantive features and significant progress compared to the prior art. Specifically:

[0029] (1) The phototransistor of the present invention can distinguish between ultraviolet light and infrared light through bidirectional light response, wherein a positive response is generated to ultraviolet light and a negative response is generated to infrared light;

[0030] (2) The present invention uses a solution method to obtain an ultra-thin indium oxide layer and an organic film during preparation, which has a low process cost compared to the traditional vacuum equipment preparation method;

[0031] (3) The present invention uses gold electrodes with high work function as source and drain electrodes to form Schottky contacts to achieve bidirectional photoresponse. Compared with the existing methods using low-dimensional materials or circuit designs, the process is simple and the cost is low.

[0032] (4) The organic matter in the present invention can serve as both an infrared photosensitive layer and a protective layer. The solution-processed oxide film is very sensitive to water and oxygen molecules in the air. The organic matter can prevent indium oxide from contacting the air, thereby improving the stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the bidirectional light-responsive transistor of the present invention.

[0034] Figure 2 This is the absorption spectrum of In2O3 and the near-infrared absorbing organic compound PTPBT-ET and In2O3 / PTPBT-ET thin film used as an example in the present invention.

[0035] Figure 3 The present invention is in the dark, at 5mW cm -2 Near infrared (NIR) and 5mW cm -2 Transfer characteristic curves under ultraviolet (UV) irradiation.

[0036] Figure 4 It is the responsiveness of the present invention to near infrared and ultraviolet light.

[0037] Figure 5 The present invention is 2.5s, 2.5mW cm -2 Near infrared and 2.5s, 2.1mW cm -2 Channel current variation under UV pulse.

[0038] Explanation of the accompanying drawings: 1. Silicon substrate; 2. Silicon dioxide dielectric layer; 3. Indium oxide semiconductor layer; 4. Source and drain electrodes; 5. Infrared photosensitive layer. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0040] like Figure 1 As shown, a positive and negative bidirectional photoresponsive transistor comprises a heavily doped conductive silicon substrate 1, a silicon dioxide dielectric layer 2 is deposited on the heavily doped conductive silicon substrate 1, a first photoresponsive structure is arranged on the silicon dioxide dielectric layer 2, and a second photoresponsive structure is arranged on the first photoresponsive structure.

[0041] Specifically, the first light-responsive structure includes an N-type semiconductor channel deposited on the silicon dioxide dielectric layer 2 and a source-drain electrode 4 arranged on the N-type semiconductor channel, and the source-drain electrode forms a Schottky junction with the N-type semiconductor channel. In this embodiment, the thickness of the silicon dioxide dielectric layer 2 is 100 nm. The N-type semiconductor channel is a patterned indium oxide semiconductor layer 3 channel, and the thickness of the N-type semiconductor layer in this embodiment is 5-10 nm. The source-drain electrode 4 is a metal electrode formed of metallic gold, and the thickness of the source-drain electrode layer is 30-50 nm. The second light-responsive structure is an organic layer having a certain wavelength light absorption capability. In this embodiment, the organic layer is a near-infrared photosensitive layer 5.

[0042] The bidirectional photoresponse is achieved by using the Schottky contact between the indium oxide layer and the source-drain electrode (Au). When irradiated with infrared light (wavelength 800nm), the organic layer of the photosensitive layer generates photogenerated carriers, of which electrons are injected into the indium oxide channel. Holes are blocked at the interface between indium oxide and organic matter due to the huge energy barrier and are bound by defect states. Next, the presence of the Schottky barrier blocks the injection of electrons, thereby accelerating the capture of electrons by defects in indium oxide, resulting in a decrease in current and a negative response to infrared light. Under the irradiation of ultraviolet light (wavelength 365nm), indium oxide itself acts as both a conductive channel and a light absorption layer. Compared to infrared light irradiation, ultraviolet light will give photoelectrons higher energy, thereby crossing the Schottky barrier and being injected into the drain, rather than tending to electrons being bound by defects, resulting in an increase in current, thereby obtaining a positive photoresponse.

[0043] The preparation method of the Schottky contact positive and negative bidirectional light-responsive transistor is as follows:

[0044] (1) Draw a specific mask according to the experimental conditions and make it using stainless steel sheets;

[0045] (2) Prepare an indium oxide precursor solution. Prepare indium nitrate, 2-methoxyethanol, acetylacetone, and ammonia water. Dissolve indium nitrate powder in 2-methoxyethanol to prepare a 0.1 mol / L indium nitrate solution. Add 0.1 mol / L acetylacetone and ammonia water as additives to promote the exothermic reaction and improve the film quality. Stir thoroughly at room temperature for 24 hours and filter with a filter with a pore size of 0.2 μm.

[0046] (3) Cleaning the substrate, cleaning the heavily doped conductive silicon substrate, and after depositing a silicon dioxide dielectric layer on the heavily doped conductive silicon substrate, cleaning the silicon dioxide dielectric layer. The substrate and silicon dioxide dielectric layer were cleaned in an ultrasonic cleaner with acetone, isopropyl alcohol, and deionized water for 10 minutes, respectively, followed by drying with high-purity nitrogen and baking on a hot plate at 105°C for 5 minutes to remove moisture.

[0047] (4) Prepare indium oxide channels using a photopatterning method. First, treat the silicon dioxide dielectric layer with a UV ozone cleaner for 10 minutes to make its surface hydrophilic. Then, spin-coat a 0.1 mol / L indium oxide precursor solution on the substrate at 3000 rpm for 30 seconds. Immediately pre-bake at 100°C for 1 minute. Then cover the film with the prepared mask and expose the patterned area to a UV ozone atmosphere for 10 minutes. The sample is then placed in an etching solution (methanol: acetic acid = 20:1, volume ratio) for 5 seconds. The unexposed part will be etched away, then washed with deionized water and blown dry with high-purity nitrogen. Next, the patterned indium oxide film is placed on a hot plate at 300 degrees Celsius and annealed for 1 hour;

[0048] (5) Source-drain electrode deposition. Using a customized mask, 30 nm of gold is evaporated on the partially patterned indium oxide channel using a thermal evaporation method to form a Schottky contact, thereby obtaining an indium oxide thin film transistor based on a Schottky contact.

[0049] (6) Preparation of a near-infrared photosensitive layer. PTPBT-ET powder was dissolved in chloroform solvent to form a 6 mg / ml solution. The PTPBT-ET solution was then dynamically spin-coated on an indium oxide thin film transistor at a speed of 3000 rpm and annealed on a hot plate at 100 degrees Celsius for 10 hours to obtain a bidirectional photoresponsive photoelectric thin film transistor.

[0050] Application 1 of this embodiment: Using the bidirectional photoresponse phototransistor based on Schottky contact of this embodiment for ultraviolet and infrared detection

[0051] The absorption spectra of In2O3 and the near-infrared absorbing organic compound PTPBT-ET and In2O3 / PTPBT-ET thin films used as examples are shown in Figure 2. Figure 2 As shown. Figure 3 As shown, when the device is irradiated with ultraviolet light, the transfer curve of the phototransistor drifts to the upper left (the threshold voltage shifts to the left and the channel current increases). When the device is irradiated with near-infrared light, the transfer curve drifts to the lower right (the threshold voltage shifts to the right and the channel current decreases). Figure 4 The device's gate voltage regulation on ultraviolet and near-infrared responsivity is demonstrated.

[0052] Application 2 of this embodiment: Using the bidirectional photoresponse phototransistor based on Schottky contact of this embodiment to perform ultraviolet and near-infrared resolution

[0053] like Figure 5 As shown, when the device is placed in V GS =V DS =20V bias, and apply 2.5mW cm for 2.5s. -2 When irradiated with near-infrared light (800 nm), the channel current experienced a short rise and then continued to decline. On the contrary, when 2.1 mW cm -2 When exposed to ultraviolet light (365nm), the channel current increases and remains stable until the light source is turned off. Therefore, the polarity of the photocurrent can be used to distinguish whether the wavelength of the incident light is near-infrared light or ultraviolet light.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A positive and negative bidirectional light-responsive transistor, characterized in that: The invention comprises a heavily doped conductive silicon substrate, on which a silicon dioxide dielectric layer is deposited, a first light-responsive structure is arranged on the silicon dioxide dielectric layer, and a second light-responsive structure is arranged on the first light-responsive structure; the first light-responsive structure comprises an N-type semiconductor channel deposited on the silicon dioxide dielectric layer and a source-drain electrode arranged on the N-type semiconductor channel, the source-drain electrode and the N-type semiconductor channel forming a Schottky junction; the second light-responsive structure is an organic layer having a certain wavelength light absorption capability; the organic layer is an organic polymer layer or a small molecule layer having near-infrared absorption capability.

2. The positive and negative bidirectional light-responsive transistor according to claim 1, characterized in that: The N-type semiconductor channel is an indium oxide channel.

3. The positive and negative bidirectional light-responsive transistor according to claim 1, characterized in that: The source and drain electrodes are gold electrodes.

4. The positive and negative bidirectional light-responsive transistor according to claim 1, characterized in that: The thickness of the silicon dioxide dielectric layer is 100 nm, the thickness of the N-type semiconductor layer is 5-10 nm, and the thickness of the source-drain electrode layer is 30-50 nm.

5. A method for preparing a positive and negative bidirectional light-responsive transistor, characterized in that: Including steps: S01. Preparing an indium oxide precursor solution; S02. Cleaning the heavily doped conductive silicon substrate, depositing a silicon dioxide dielectric layer on the heavily doped conductive silicon substrate, and then cleaning the silicon dioxide dielectric layer; S03 spin-coating an indium oxide precursor solution on the silicon dioxide dielectric layer, and preparing an indium oxide channel by photolithography or optical patterning; S04 depositing a source and drain electrode made of metallic gold on the indium oxide semiconductor layer to form a Schottky contact indium oxide thin film transistor; S05. After subjecting the indium oxide thin film transistor to ultraviolet ozone treatment to make its surface hydrophilic, an organic substance is dynamically spin-coated on the indium oxide thin film transistor to form a bidirectional light-responsive transistor, wherein the organic substance is an organic polymer or small molecule with near-infrared absorption capability.

6. The method for preparing a positive and negative bidirectional light-responsive transistor according to claim 5, characterized in that: Step S03 includes: S031. UV-ozone treatment of the silicon dioxide dielectric layer for 10 min to make its surface hydrophilic; S032. The indium nitrate precursor solution is spin-coated on the silicon dioxide dielectric layer and pre-baked at 100°C to form a sol-gel film; S033. Cover the film with a mask and irradiate it under deep ultraviolet light for 10 minutes; S034. The sample is etched, and the unexposed area is dissolved by the etching solution, leaving the exposed portion of the film; S035. The sample was washed with deionized water and dried with nitrogen, and the patterned indium oxide film was annealed at 300°C for 1 h.

7. The method for preparing a positive and negative bidirectional light-responsive transistor according to claim 5, characterized in that: Step S05 includes: S051. The organic compound is an organic polymer or small molecule with near-infrared absorption capability; S052. UV-ozone treatment of Schottky indium oxide thin film transistors for 30 seconds to make the surface hydrophilic; S053. Dynamically spin-coat the organic solution and anneal at 100°C for 5 min.

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