A field-manipulated tunable photoelectric sensitive detector, its fabrication method and its application

Abstract

This invention provides a field-controlled tunable photoelectric sensitive detector, its fabrication method, and its application. Tungsten disulfide nanosheets are dry-transferred onto a silicon substrate covered with silicon dioxide. Field-controlled electrodes are fabricated on the tungsten disulfide nanosheets, and source / drain electrodes are fabricated at both ends. The tungsten disulfide nanosheets serve as photosensitive conductive channels for the field-controlled electrodes and the source / drain electrodes. Applying a voltage to the field-controlled electrodes and the source / drain electrodes increases the photoresponse current and reduces the dark current through an asymmetric electric field. This invention provides a field-controlled tunable photoelectric sensitive detector, its fabrication method, and its application to improve the detector's responsivity.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection device technology, and in particular to a field-controlled tunable photoelectric sensitivity detection device, its preparation method, and its application. Background Technology

[0002] A photodetector is an optoelectronic device that converts optical signals into electrical signals. It acts as the "eye" of an optoelectronic system and is widely used in video imaging, optical communication, night vision devices, and medical imaging. Over the past decade, two-dimensional (2D) materials have become ideal materials and a research focus for photodetectors. The main reasons include: 2D materials are diverse and have tunable band gaps, enabling photodetectors based on 2D materials to achieve broad-spectrum detection from ultraviolet to terahertz wavelengths; the fabrication of 2D materials is not constrained by lattice matching, and the fabrication methods are simple and inexpensive, with mechanical exfoliation being the most common method, used to prepare the world's first monolayer graphene; generally, 2D materials have higher carrier mobility than bulk materials, allowing for strong interactions with external light and achieving high responsivity.

[0003] Currently commercially available photodetectors are mainly made of semiconductor materials such as silicon, mercury cadmium telluride, and indium gallium arsenide. However, these traditional detectors often have drawbacks such as large device size, toxicity, low operating temperature, and complex manufacturing process.

[0004] Therefore, how to solve the problems of poor light absorption and low photoresponse current of two-dimensional materials has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned problems, the first objective of this invention is to provide a field-controlled tunable photoelectric sensitivity detector that improves the detector's responsivity.

[0006] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0007] A field-controlled tunable photoelectric sensitive detector is disclosed, wherein tungsten disulfide nanosheets are dry-transferred onto a silicon substrate covered with silicon dioxide. Field control electrodes are fabricated on the tungsten disulfide nanosheets, and source / drain electrodes are fabricated at both ends. The tungsten disulfide nanosheets serve as photosensitive conductive channels for the field control electrodes and the source / drain electrodes at both ends. A voltage is applied to the field control electrodes and the source / drain electrodes, and the photoresponse current is increased and the dark current is reduced by an asymmetric electric field.

[0008] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0009] As a preferred technical solution of the present invention: dry transfer of boron nitride nanosheets onto tungsten disulfide nanosheets, and preparation of field control electrodes on the boron nitride nanosheets.

[0010] As a preferred embodiment of the present invention, the boron nitride nanosheets have a length of 10~14 μm, a width of 4~9 μm, and a thickness of 10~45 nm.

[0011] As a preferred embodiment of the present invention, the thickness of the silicon substrate covered with silicon dioxide is 0.8~1 mm;

[0012] The tungsten disulfide nanosheets have a length of 12-15 μm and a width of 4-7 μm.

[0013] The source and drain electrodes are made of gold and have a thickness of 80~100 nm.

[0014] The field control electrode is made of gold, with a linewidth of 1~2 μm and a thickness of 80~100 nm.

[0015] The tungsten disulfide nanosheets described herein have a conductive channel length of 12–15 μm and a mobility of 30–50 cm⁻¹. 2 V -1 s -1 .

[0016] The second objective of this invention is to provide a method for fabricating a field-controlled tunable photoelectric sensitivity detector to improve the detector's responsivity.

[0017] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0018] The method for fabricating the field-manipulated tunable photoelectric sensitivity detector is characterized by:

[0019] S1, clean the surface of the silicon substrate covered with silicon dioxide, and cut the substrate into pieces with a size of 1 cm × 1 cm;

[0020] S2, using a transfer platform and micro-area positioning method, dry transfer technology is used to transfer mechanically exfoliated tungsten disulfide nanosheets onto the substrate prepared in step S1, and numbering and positioning markings are performed.

[0021] S3 combines ultraviolet lithography, electron beam evaporation, and exfoliation processes to prepare source / drain electrodes and field manipulation electrodes that are in contact with tungsten disulfide nanosheets, forming a good contact.

[0022] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0023] As a preferred technical solution of the present invention: In step S3, the mechanically peeled boron nitride nanosheets are transferred to the above-mentioned source and drain electrodes by means of a transfer platform and a micro-area positioning method, using dry transfer technology, so as to form good contact with the source and drain electrodes and the field control electrode to act as a gate or induce a bias electric field.

[0024] As a preferred technical solution of the present invention: In step S3, a thickened electrode with a thickness of about 300~400 nm is prepared by ultraviolet lithography, electron beam evaporation and stripping process for subsequent lead wire testing.

[0025] Another objective of this invention is to provide applications for the field-manipulated tunable photoelectric sensitivity detector described above, in fields such as video imaging, photoelectric detection, and optical communication.

[0026] This invention discloses a field-manipulated tunable photoelectric sensitive detector, its fabrication method, and its applications. A photodetector capable of dynamically controlling photogenerated carriers is fabricated using tungsten disulfide and boron nitride materials. This photodetector uses tungsten disulfide, which has high carrier mobility and a wide response band, as the basic structural unit, silicon dioxide as the substrate, a butterfly antenna as the metal electrode, and a wide-bandgap boron nitride as the gate dielectric layer. It can achieve photoelectric detection at room temperature through joint control of gate voltage and asymmetric electric field. The detector of this invention exhibits advantages such as low dark current, high responsivity, high sensitivity, multiple control modes, high repeatability, and stability in air, laying the device and theoretical foundation for research on highly integrated visible light detection at room temperature. The field-manipulated tunable photoelectric sensitive detector of this invention employs two special structures, utilizing an asymmetric electric field and an applied gate voltage to synergistically control the carriers in the channel, ultimately improving the detector's responsivity. Attached Figure Description

[0027] Figure 1 This is a top view schematic diagram of Embodiment 1 of the field-controlled adjustable photoelectric sensitivity detector of the present invention;

[0028] Figure 2 This is a front view schematic diagram of Embodiment 1 of the field-controlled adjustable photoelectric sensitivity detector of the present invention;

[0029] Figure 3 This is a top view schematic diagram of Embodiment 2 of the field-controlled adjustable photoelectric sensitivity detection device of the present invention;

[0030] Figure 4 This is a front view schematic diagram of Embodiment 2 of the field-controllable adjustable photoelectric sensitivity detector of the present invention;

[0031] Figure 5 The output characteristic curve I of the field-controlled adjustable photoelectric sensitivity detector of the present invention at room temperature.DS -V DS ;

[0032] Figure 6 This is a spatial distribution diagram of the photoresponse current at room temperature for the field-controlled adjustable photoelectric sensitivity detector of the present invention.

[0033] Figure 7 This is a schematic diagram illustrating the change of photocurrent with gate voltage under different bias voltages for the field-controlled adjustable photoelectric sensitive detector of the present invention.

[0034] Figure 8 This is a schematic diagram illustrating the change of photocurrent with bias voltage under different gate voltages in the field-controlled adjustable photoelectric sensitive detector of the present invention.

[0035] Figure 9 The photoresponse current distribution diagram is shown under the combined control of bias voltage and gate voltage;

[0036] Figure 10 This is a diagram showing the photoresponse current distribution of a long-channel device.

[0037] Figure 11 This is a diagram showing the photoresponse current distribution of a short-channel device.

[0038] In the attached figure, 1 is a silicon substrate covered with silicon dioxide, 2 is a source / drain electrode, 3 is a boron nitride nanosheet, 4 is a field manipulation electrode, and 5 is a tungsten disulfide nanosheet. Detailed Implementation

[0039] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, this invention discloses a field-controlled tunable photoelectric sensitive detector. The detector comprises a mechanically exfoliated tungsten disulfide nanosheet 5 dry-transferred onto a silicon substrate 1 covered with silicon dioxide. Source / drain electrodes 2 are fabricated at both ends of the tungsten disulfide nanosheets. Boron nitride nanosheets 3 are selectively dry-transferred onto the tungsten disulfide nanosheets. A field-controlled electrode 4 is fabricated on either the tungsten disulfide or boron nitride nanosheets, which can act as a gate or induce a bias electric field. Using tungsten disulfide, a material with high carrier mobility and tunable bandgap, as the photosensitive conductive channel, the bandgap of tungsten disulfide is related to the number of layers. When the number of layers is reduced from multiple layers to a single layer, the indirect bandgap becomes a direct bandgap. Through structural design and electric field modulation of the tungsten disulfide nanosheets, a highly sensitive, highly responsible, low dark current, and highly integrated photoelectric detector is achieved.

[0040] The present invention discloses a field-controlled tunable photoelectric sensitive detector. It utilizes two-dimensional tungsten disulfide with high mobility and tunable carrier concentration as the basic structural unit to construct a photoelectric sensitive detector. By combining a set of metal butterfly source and drain electrodes and metal field control electrodes, a visible light detector with a two-dimensional tungsten disulfide / field control electrode / two-dimensional boron nitride / silicon substrate covered with silicon dioxide structure is realized at room temperature. It can achieve low dark current, high responsivity and dynamic controllable photoelectric detection.

[0041] The photodetector of this invention utilizes two-dimensional tungsten disulfide material as the photosensitive conductive channel, achieving non-toxic, highly stable, low dark current, and room-temperature photodetection. Furthermore, the basic structural unit of the detector has dimensions of approximately tens of micrometers, laying the foundation for miniaturized and highly integrated visible light functional devices. Compared to conventional tungsten disulfide-based photodetectors, the detector of this invention utilizes a field-controlled electrode and a pair of source-drain electrodes, allowing voltage to be applied to all three terminals, achieving an asymmetric electric field. This results in a larger photoresponse current and a lower dark current.

[0042] In this invention, both the gate voltage applied to the field control electrode and the bias voltage applied to the source / drain electrode can regulate the carrier concentration and mobility in the channel. Not only can the photoresponse current of the detector be increased by simultaneously increasing the gate voltage and source / drain voltage, but the sign of the photoresponse current can also be changed by altering the polarity of the gate voltage or source / drain voltage. These two methods enable dynamic, rapid, and coordinated control of carriers, achieving multi-dimensional detection of visible light waves.

[0043] In the photodetector of the present invention, boron nitride coated on tungsten disulfide is a wide bandgap semiconductor material with a bandgap of 6.1 to 6.4 eV. This increases the voltage that can be applied to the gate, providing external conditions for the detector to generate a larger photoresponse current. The gate voltage does not directly form an electric field that affects the tungsten disulfide channel, but attracts or repels electrons in the channel through Coulomb interaction, thereby achieving the regulation of carrier concentration, migration direction and mobility.

[0044] The present invention discloses a field-manipulated tunable photoelectric sensitivity detector, the specific preparation method of which is as follows:

[0045] Step 1: First, the silicon substrate covered with silica is cleaned, and then the substrate is cut into samples with a size of 1 cm × 1 cm using a cutting technique.

[0046] Step 2: Using a transfer platform and micro-area positioning method, the mechanically peeled tungsten disulfide nanosheets are transferred to the cleaned and cut substrate using dry transfer technology, and then numbered and positioned.

[0047] Step 3: Use ultraviolet lithography, electron beam evaporation and lift-off process to prepare source and drain electrodes and field control electrodes in contact with nanosheets to form good contact;

[0048] Step 4: Using a transfer platform and micro-area positioning method, the mechanically exfoliated boron nitride nanosheets are transferred to the above-mentioned source and drain electrodes using dry transfer technology, and then numbered and positioned.

[0049] Step 5: Fabricate the metal gate using a combination of ultraviolet lithography, electron beam evaporation, and lift-off processes;

[0050] Step 6: A thickened electrode with a thickness of approximately 300-400 nm is prepared using ultraviolet lithography, electron beam evaporation, and lift-off processes for subsequent wire bonding testing.

[0051] Step 7: Package and test the device using standard semiconductor packaging technology.

[0052] Step 8: Select a laser source with a wavelength of 520 nm, and focus it onto the detector through a microscope system via electrical modulation. The photoresponse signal generated by the detector is amplified by a preamplifier (SR570) and input into an oscilloscope and a lock-in amplifier (SR830). In addition, an electrical modulation frequency is required as a reference signal and input into the oscilloscope and the lock-in amplifier respectively to ensure accurate recording of the photoresponse current of the device under different bias voltages and to test the photoelectric characteristics of the detector under different optical power densities.

[0053] The field-controlled adjustable photoelectric sensitive detector of the present invention has extremely sensitive light response and large photocurrent to visible light signals. The field-controlled adjustable photoelectric sensitive detector of the present invention has great application potential in video imaging, photoelectric detection, optical communication and other fields. The external gate electric field and source drain electric field can synergistically control the magnitude and sign of the photoresponse current, which lays the device and theoretical foundation for the detector in automatic control, optical switching and other fields.

[0054] Example 1

[0055] The silicon substrate covered with silica has a thickness of 0.8 mm; the tungsten disulfide nanosheets have a length of 14 μm and a width of 6 μm, and the source / drain electrodes have a thickness of 90 nm; the metal gate linewidth is 1 μm, the thickness is 90 nm, the conductive channel length is 10 μm, and the mobility is 35 cm⁻¹. 2 V -1 s -1 ; Figure 5 The figure shows the output characteristic curve of the device at room temperature. It can be seen that the detector has a large photoresponse current and a very low dark current, enabling high-performance detection of visible light with high responsivity and low dark current. Figure 6As shown, under laser irradiation, a photoresponse current is generated at the contact point between the tungsten disulfide nanosheet and the source / drain electrodes, similar to a photovoltaic response. This is because the tungsten disulfide forms a Schottky contact with the source / drain electrodes. Under dark conditions, the built-in electric fields at both ends are in opposite directions, resulting in a very low dark current in the detector. Under illumination, the detector exhibits a high response to the laser, and the polarity of the photoresponse current reverses significantly with changes in the scanning area, verifying that the built-in electric fields at both ends of the device are opposite. In summary, the difference in the magnitude and polarity of the built-in electric field leads to the generation of a mirror current, which lays the theoretical foundation for dynamically controlling visible light detection.

[0056] Example 2

[0057] The silicon substrate covered with silica has a thickness of 0.9 mm; the tungsten disulfide nanosheets have a length of 10 μm and a width of 7 μm, the boron nitride nanosheets have a thickness of 20 μm, and the source / drain electrodes have a thickness of 100 nm; the metal gate has a linewidth of 1 μm, a thickness of 90 nm, a conductive channel length of 10 μm, and a mobility of 35 cm⁻¹. 2 V -1 s -1 ;like Figure 7 As shown, the bias voltage can significantly enhance the photoresponse current of the detector; as the bias voltage increases, the amplitude of the photocurrent also increases. Figure 8 As shown, the photocurrent changes with the magnitude and polarity of the gate voltage. Experiments show that a larger gate voltage leads to a larger photocurrent, and the polarity of the photocurrent reverses during this modulation process. Figure 9 As shown, when both the bias voltage and the gate voltage are 4V, the device generates a significant photocurrent response, which fully demonstrates that the gate voltage and the bias voltage have a significant synergistic control capability over the photocurrent.

[0058] Example 3

[0059] The silicon substrate covered with silica has a thickness of 0.9 mm; the tungsten disulfide nanosheets have a length of 10 μm and a width of 7 μm; the source / drain electrode thickness is 90 nm; the shortest conductive channel between the source / drain electrodes has a length of 5 μm and a mobility of 50 cm⁻¹. 2 V -1 s -1 The relatively long conductive channel between the source and drain electrodes is 8 μm in length and has a mobility of 40 cm⁻¹. 2 V -1 s -1 ;like Figure 10 As shown, when the channel is long, the amplitude of the photocurrent is low, such as... Figure 11As shown, the photocurrent amplitude increases significantly when the channel is short. Regardless of the channel length, the photocurrent polarity reverses, further demonstrating that the tungsten disulfide and the source / drain electrodes form a Schottky contact. In summary, the photocurrent response of the detector can be significantly modulated by changing the length of the conductive channel.

[0060] Various parameters of the detector vary within a certain range. The room-temperature field-controlled tunable photodetector described in this invention exhibits excellent performance. Test results show that the photoelectric response of the detector can be significantly modulated by inducing a bias electric field and applying an external gate voltage. Since the tungsten disulfide material and the source / drain electrodes form a Schottky contact, the photocurrent response of the device exhibits mirror symmetry, and the device possesses a photovoltaic-like detection mode. Finally, shortening the channel length enhances the photoresponse current, providing a direction for the design of visible light detection devices. In summary, the room-temperature operating, low dark current, high responsivity, and dynamically tunable photodetector provides a promising research direction for the design of high-performance photodetectors.

[0061] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A field-controlled adjustable photoelectric sensitivity detection device, characterized in that: Tungsten disulfide nanosheets are dry-transferred onto a silicon substrate covered with silica. Boron nitride nanosheets are then dry-transferred onto the tungsten disulfide nanosheets. Field control electrodes are fabricated on the boron nitride nanosheets. Source and drain electrodes are fabricated at both ends of the tungsten disulfide nanosheets. Schottky contacts are formed between the tungsten disulfide nanosheets and the source and drain electrodes. The tungsten disulfide nanosheets serve as a photosensitive conductive channel for the field control electrodes and the source and drain electrodes fabricated at both ends. A voltage is applied to the field control electrodes and the pair of source and drain electrodes. A voltage is applied to all three electrodes to achieve an asymmetry in the electric field, thereby generating a larger photoresponse current and a lower dark current. The gate voltage applied to the field control electrode and the bias voltage applied to the source and drain electrodes both regulate the carrier concentration and mobility in the channel. This not only increases the photoresponse current of the detector by simultaneously increasing the gate voltage and the source and drain voltage, but also changes the sign of the photoresponse current by changing the polarity of the gate voltage or the source and drain voltage, thus enabling multi-dimensional detection of visible light waves.

2. The field-controlled adjustable photoelectric sensitivity detector as described in claim 1, characterized in that: The boron nitride nanosheets have a length of 10-14 μm, a width of 4-9 μm, and a thickness of 10-45 nm.

3. The field-manipulated adjustable photoelectric sensitivity detector as described in claim 1, characterized in that: The thickness of the silicon substrate covered with silicon dioxide is 0.8~1 mm; The tungsten disulfide nanosheets have a length of 12-15 μm and a width of 4-7 μm. The source and drain electrodes are made of gold and have a thickness of 80~100 nm. The field control electrode is made of gold, with a linewidth of 1~2 μm and a thickness of 80~100 nm. The tungsten disulfide nanosheets described herein have a conductive channel length of 12–15 μm and a mobility of 30–50 cm⁻¹. 2 V -1 s -1 .

4. The method for fabricating the field-manipulated tunable photoelectric sensitivity detector according to any one of claims 1-3, characterized in that: S1, clean the surface of the silicon substrate covered with silicon dioxide, and cut the substrate into pieces with a size of 1 cm × 1 cm; S2, using a transfer platform and micro-area positioning method, dry transfer technology is used to transfer mechanically exfoliated tungsten disulfide nanosheets onto the substrate prepared in step S1, and numbering and positioning markings are performed. S3 combines ultraviolet lithography, electron beam evaporation, and exfoliation processes to prepare source / drain electrodes and field manipulation electrodes that are in contact with tungsten disulfide nanosheets, forming a good contact.

5. The method for fabricating the field-manipulated tunable photoelectric sensitivity detector as described in claim 4, characterized in that: In step S3, the mechanically exfoliated boron nitride nanosheets are transferred to the source and drain electrodes using a dry transfer technique via a transfer platform and a micro-region positioning method. This allows them to form good contact with the source and drain electrodes and the field control electrode to act as a gate or induce a bias electric field.

6. The method for fabricating the field-manipulated tunable photoelectric sensitivity detector as described in claim 4, characterized in that: In step S3, a thickened electrode with a thickness of 300~400 nm is prepared by ultraviolet lithography, electron beam evaporation and lift-off process for subsequent lead wire testing.

7. The field-controlled adjustable photoelectric sensitivity detector as described in any one of claims 1-3 is applied in the fields of video imaging, photoelectric detection, and optical communication.

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