A high-orientation tellurium thin film photothermal electric detector and a preparation method thereof

Abstract

The application discloses a high-orientation tellurium thin film photothermal electric detector and belongs to the field of semiconductor devices. The high-orientation tellurium thin film photothermal electric detector comprises an amorphous substrate and a Te thin film deposited on the amorphous substrate, wherein the ratio of the peak intensity of the (100) crystal face of the Te thin film to the total peak intensity of X-ray diffraction of the Te thin film is not less than 80%, the crystal c-axis [0001] direction of the Te thin film is parallel to the surface of the amorphous substrate, and the internal crystal domain size of the Te thin film crystal is 5-10 microns; two metal electrodes are arranged at the two ends of the Te thin film, form electrical contact with the Te thin film and constitute a transverse channel structure, and when light is irradiated in the transverse channel, a temperature gradient is generated to drive directional migration of carriers to realize detection. The high-orientation tellurium thin film photothermal electric detector disclosed by the application solves the limitations of the prior art in substrate universality, orientation control and device performance regulation.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material preparation and optoelectronic device technology, specifically, it relates to a highly oriented tellurium thin film photothermal detector and its preparation method. Background Technology

[0002] Tellurium (Te) is a narrow-bandgap p-type semiconductor material with a bandgap of approximately 0.33 eV. It exhibits high hole mobility and excellent thermoelectric properties, making it promising for applications in photothermoelectric photoelectric (PTE) detection, flexible electronics, and thermoelectric conversion. The narrow bandgap characteristic endows it with mid-wave infrared response capability, and Te itself possesses good environmental stability and high toughness, making it particularly suitable for constructing room-temperature, bias-free photothermoelectric detectors. Compared to traditional photovoltaic or photoconductive devices, planar PTE detectors can operate without bias, offering advantages such as low noise, wide-spectrum response, and self-powered operation, making them invaluable in room-temperature infrared detection and imaging.

[0003] However, existing Te thin film fabrication technologies still have significant shortcomings. First, traditional high-temperature methods (such as molecular beam epitaxy, pulsed laser deposition, and chemical vapor deposition) typically require temperatures above 400°C, which severely limits substrate selection. Flexible or temperature-sensitive substrates are prone to failure under these conditions. Furthermore, the high-temperature process often results in small domain sizes and high surface roughness, making it difficult to achieve high-quality growth on low-cost amorphous substrates (such as glass and quartz). Second, while recent low-temperature thermal evaporation processes have made some progress on crystalline substrates, these methods are highly dependent on the lattice template-induced effect of the substrate and cannot be directly applied to amorphous substrates. Consequently, Te thin films grown on amorphous substrates such as glass often exhibit disordered orientation and small domains, making it difficult to meet the fabrication requirements of high-performance planar photothermal detectors.

[0004] On the other hand, existing Te-based optoelectronic devices mostly employ vertical heterojunction structures, which are complex to fabricate and costly. In contrast, planar photothermal detectors have unique advantages in device structure, physical mechanism, and performance optimization. However, due to the lack of effective methods for fabricating highly oriented, large-domain Te thin films on amorphous substrates, it is currently difficult to realize low-cost, easily integrated, and size-tunable planar PTE detectors, thus limiting their application in practical applications such as flexible thermal imaging and large-scale array detection.

[0005] Therefore, there is an urgent need to develop a method for preparing (100) preferred orientation, large domain Te thin films on low-cost amorphous substrates and apply it to size-tunable planar photothermal detectors to overcome the limitations of existing technologies in terms of substrate compatibility, crystal orientation control, device configuration optimization and large-scale preparation, and to provide a new technical path for the development of high-performance photothermal devices. Summary of the Invention

[0006] To address the shortcomings and improvement needs of existing technologies, this invention provides a highly oriented tellurium thin film photothermal detector and its fabrication method. The purpose is to achieve the fabrication of a large-domain Te thin film with (100) preferred orientation on an amorphous substrate completely lacking a lattice-induced template through a controlled temperature thermal evaporation process, and to construct a planar detector based on the thin film. This detector achieves zero-bias operation by utilizing the photothermal PTE effect, and the detector response voltage sensitivity can be optimized by precisely adjusting the geometric dimensions such as the width and length of the channel. This solves the limitations of existing technologies in substrate versatility, orientation control, and device performance regulation.

[0007] To achieve the above objectives, according to one aspect of the present invention, a highly oriented tellurium thin-film photothermal detector is provided, comprising: Amorphous substrate; Te thin film, Te thin film deposited on amorphous substrate, wherein the peak intensity of the (100) crystal plane of the Te thin film accounts for no less than 80% of the total peak intensity of its X-ray diffraction, the c-axis

[0001] direction of the Te thin film crystal is parallel to the surface of the amorphous substrate, and the size of the crystal domain inside the Te thin film crystal is 5μm~10μm; Two metal electrodes are disposed at both ends of the Te thin film, forming an electrical contact with the Te thin film and constituting a transverse channel structure. When light shines on the transverse channel and generates a temperature gradient, it drives the directional migration of charge carriers to achieve detection.

[0008] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: This invention enables temperature-controlled growth of (100) preferred orientation, large domain Te thin films on low-cost, widely available amorphous substrates (such as glass and quartz), completely eliminating the dependence on expensive single-crystal substrates and their lattice template effects, and providing a brand-new technical path for large-scale, low-cost preparation of high-quality Te thin films.

[0009] Achieving a unique (100) crystal texture lays the foundation for device materials: The Te thin film prepared by this invention has a strong (100) preferred orientation and a crystal domain size of 5μm to 10μm, which effectively solves the technical problems of chaotic orientation and small crystal domains of Te thin films on existing amorphous substrates, and provides an ideal material basis for constructing high-performance planar optoelectronic devices.

[0010] This invention proposes a novel device configuration to expand application directions: Based on the aforementioned thin film, a size-adjustable planar photothermal PTE detector is constructed. By precisely controlling the channel width and length, the response voltage sensitivity can be optimized. This device configuration differs fundamentally from existing vertical photovoltaic devices in terms of device structure, physical principles, and performance optimization paths, and can more fully utilize the excellent thermoelectric properties of Te material.

[0011] High process compatibility and easy to scale up: The temperature-controlled thermal evaporation deposition and standard photolithography process used in this invention are highly compatible with existing semiconductor integrated circuit technology, making it easy to fabricate large-area, arrayed devices and possessing good practical application potential. Attached Figure Description

[0012] Figure 1 The diagram shown is a schematic diagram of a highly oriented tellurium thin film photothermal detector provided according to an embodiment of the present invention.

[0013] Figure 2 The diagram shows a fabrication process flow diagram of a highly oriented tellurium thin film photothermal detector according to an embodiment of the present invention.

[0014] Figure 3 The image shown is an X-ray diffraction (XRD) pattern of a Te thin film prepared according to an embodiment of the present invention.

[0015] Figure 4 The image shown is a polarized light microscope image of a Te thin film provided according to an embodiment of the present invention, used to demonstrate its large-size crystal domains.

[0016] Figure 5 The image shown is an optical microscope photograph of a highly oriented tellurium thin film photothermal detector prepared according to an embodiment of the present invention.

[0017] Figure 6 The figure shows the responsivity curves of a highly oriented tellurium thin film photothermal detector with different channel widths H according to an embodiment of the present invention, as a function of 520 nm incident laser power density.

[0018] Figure 7 The figure shows the responsivity curves of a highly oriented tellurium thin film photothermal detector with different channel lengths L according to an embodiment of the present invention, as a function of the incident laser power density at 520 nm.

[0019] Figure 8 The figure shows the dark current-voltage (IV) curves of a highly oriented tellurium thin film photothermal detector with different channel widths H according to an embodiment of the present invention.

[0020] Figure 9 The figure shows a typical photothermal response time curve of a highly oriented tellurium thin film detector provided according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In this invention, the terms "first," "second," etc. (if present) in the invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0023] Example 1: This invention discloses a highly oriented tellurium thin-film photothermal detector, such as... Figure 1 As shown, it includes: Amorphous substrates, specifically, including but not limited to glass or quartz.

[0024] Te thin film, Te thin film deposited on amorphous substrate, wherein the peak intensity of the (100) crystal plane of the Te thin film accounts for no less than 80% of the total peak intensity of its X-ray diffraction, the c-axis

[0001] direction of the Te thin film crystal is parallel to the surface of the amorphous substrate, and the size of the crystal domain inside the Te thin film crystal is 5μm~10μm; Two metal electrodes are disposed at both ends of a Te thin film, forming an electrical contact with the Te film and constituting a transverse channel structure. When light shines into the transverse channel, generating a temperature gradient, it drives the directional migration of charge carriers to achieve detection. In one embodiment, the method for generating the temperature gradient includes, but is not limited to, irradiating one end of the transverse channel with light while leaving the other end unirradiated; or irradiating one end with strong light while the other end with weak light. When charge carriers move directionally in the transverse channel, i.e., from the hot end to the cold end of the transverse channel, they are collected and detected by the metal electrodes. Specifically, the metal electrodes include gold or nickel / gold multilayer electrodes.

[0025] In one embodiment of the present invention, the highly oriented tellurium thin-film photothermal detector is dimensionally adjustable, wherein the width of the transverse channel is 2µm to 180µm and the length is 60µm to 1000µm; the detector's electrical signal responsivity is controlled by adjusting the geometry of the transverse channel. In other words, the length and width of the transverse channel are customized to match the detection requirements according to the needs of the application scenario.

[0026] The highly oriented tellurium thin film photothermal detector of this invention has the characteristic of accurately responding to electrical signals, which solves the limitations of existing technologies in substrate versatility, orientation control and device performance regulation.

[0027] Example 2: A method for preparing the highly oriented tellurium thin film photothermal detector in Example 1, as follows: Figure 2As shown, it includes: S1: On a clean amorphous substrate, a patterned photoresist mask is formed to define a thin film region, for example by photolithography. S2: Place the substrate with the mask in a vacuum thermal evaporation system, maintain the amorphous substrate between -100°C and 120°C, use Te as the evaporation source to perform thermal evaporation deposition, and obtain a Te thin film. The temperature maintenance includes, but is not limited to, using a temperature control system. S3: After deposition, the amorphous substrate and Te film are restored to room temperature under vacuum at an average temperature change rate of 0.1 to 1 °C / min to promote Te film crystallization and domain growth; S4: After obtaining a patterned Te film through a lift-off process, two metal electrodes are fabricated on the film surface using photolithography, metal deposition, and lift-off processes.

[0028] Specifically, through the above preparation method, the peak intensity of the (100) crystal plane of the Te thin film in S2 accounts for no less than 80% of the total peak intensity of its X-ray diffraction. The c-axis

[0001] direction of the Te thin film crystal is parallel to the surface of the amorphous substrate, and the size of the internal crystal domains of the Te thin film crystal is 5μm to 10μm. In S2, the vacuum degree of thermal evaporation deposition is less than 2×10⁻⁶. -4 Pa, the deposition rate is between 0.2 and 0.5 Å / s. In S2, the Te evaporation source is Te particles or Te powder with a purity of not less than 99.999%; the total thickness of the deposited Te film is 100 nm to 300 nm.

[0029] In one embodiment, the metal electrode in S4 is prepared by vacuum thermal evaporation or electron beam evaporation, and the electrode material includes gold or nickel / gold stack.

[0030] The highly oriented tellurium thin film photothermal detector obtained by the above preparation method includes the following structure: an amorphous substrate; a Te thin film deposited on the amorphous substrate, wherein the peak intensity of the (100) crystal plane of the Te thin film accounts for not less than 80% of the total peak intensity of its X-ray diffraction; two metal electrodes disposed at both ends of the Te thin film, forming a transverse channel structure between the two metal electrodes. The working mechanism of the highly oriented tellurium thin film photothermal detector in this invention is mainly the photothermal effect PTE, which drives the directional migration of charge carriers to achieve detection.

[0031] The highly oriented tellurium thin film photothermal detector in Example 1 of this invention can be prepared using the preparation method in Example 2.

[0032] To better verify the effectiveness of the highly oriented tellurium thin film photothermal detector in this invention, experimental verification will be conducted next.

[0033] Figures 3 to 9 The characterization results of the thin films and devices prepared by the method of this embodiment are shown.

[0034] Figure 3 The XRD pattern clearly shows that the film has a dominant (100) diffraction peak, proving its highly (100) preferred orientation. Figure 4 The polarized light microscope images (scale bar 10 μm) visually demonstrate that the film is composed of large-sized crystal domains, with areas generally ranging from 5 μm to 10 μm, further confirming the high crystallinity of the film. Figure 5 The optical microscope image of the fabricated device clearly shows the lateral channel region composed of gold electrodes on both sides and a Te thin film in the middle, and its structure is consistent with the planar device structure of the present invention.

[0035] In device performance testing, Figure 6 The curves showing the responsivity of the detector under zero bias voltage with different channel widths H are presented, showing that the response is optimal when H = 2 μm. Figure 7 The curves showing the responsivity of the detector as a function of optical power density under different channel lengths L are presented, showing that the responsivity is optimal when L=100μm. Figure 8 IV curves for different channel widths H are presented, showing good ohmic characteristics and extremely low dark current. Figure 9 The response time of the device is given, with both rise and fall times within 3 ms, indicating that the device has a fast photothermal-electric response capability.

[0036] In summary, this embodiment verifies the feasibility of the technical solution of the present invention. It achieves temperature-controlled growth of (100) preferred orientation, large domain Te thin films on low-cost, widely available amorphous substrates (such as glass and quartz), completely eliminating the dependence on expensive single crystal substrates and their lattice template effects. On this basis, a photothermal detector is constructed. Through precise adjustment of the channel geometry, the internal photothermal temperature field and response sensitivity are optimized and controlled, providing robust technical support for high-performance, easily integrated flexible infrared detection and large-scale array applications.

[0037] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A highly oriented tellurium thin-film photothermal detector, characterized in that, include: Amorphous substrate; Te thin film, Te thin film deposited on amorphous substrate, wherein the peak intensity of the (100) crystal plane of the Te thin film accounts for no less than 80% of the total peak intensity of its X-ray diffraction, the c-axis [0001] direction of the Te thin film crystal is parallel to the surface of the amorphous substrate, and the size of the crystal domain inside the Te thin film crystal is 5μm~10μm; Two metal electrodes are disposed at both ends of the Te thin film, forming an electrical contact with the Te thin film and constituting a transverse channel structure. When light shines on the transverse channel and generates a temperature gradient, it drives the directional migration of charge carriers to achieve detection.

2. The highly oriented tellurium thin-film photothermal detector according to claim 1, characterized in that, Amorphous substrates include glass or quartz.

3. The highly oriented tellurium thin-film photothermal detector according to claim 1, characterized in that, Metal electrodes include gold or nickel / gold stacked electrodes.

4. The highly oriented tellurium thin-film photothermal detector according to claim 1, characterized in that, The detector size is adjustable, with the width of the transverse channel ranging from 2µm to 180µm and the length ranging from 60µm to 1000µm.

5. A method for fabricating a highly oriented tellurium thin-film photothermal detector according to any one of claims 1-4, characterized in that, Includes the following steps: S1: On a clean amorphous substrate, a patterned photoresist mask is formed to define the thin film region; S2: Place the substrate with the mask in a vacuum thermal evaporation system, maintain the amorphous substrate between -100℃ and 120℃, and perform thermal evaporation deposition using Te as the evaporation source to obtain a Te thin film; S3: After deposition, the amorphous substrate and Te film are restored to room temperature under vacuum at an average temperature change rate of 0.1 to 1 °C / min to promote Te film crystallization and domain growth; S4: After obtaining a patterned Te film through a lift-off process, two metal electrodes are fabricated on the film surface using photolithography, metal deposition, and lift-off processes.

6. The preparation method according to claim 5, characterized in that, The peak intensity of the (100) crystal plane of the Te thin film in S2 accounts for no less than 80% of the total peak intensity of its X-ray diffraction. The c-axis [0001] direction of the Te thin film crystal is parallel to the surface of the amorphous substrate, and the size of the internal crystal domains of the Te thin film crystal is 5μm to 10μm.

7. The preparation method according to claim 5, characterized in that, In S2, the vacuum level of thermal evaporation deposition is less than 2 × 10⁻⁶. -4 Pa, deposition rate between 0.2 and 0.5 Å / s.

8. The preparation method according to claim 5, characterized in that, In S2, the Te evaporation source is Te particles or Te powder with a purity of not less than 99.999%; the total thickness of the deposited Te film is 100nm to 300nm.

9. The preparation method according to claim 5, characterized in that, In S4, the metal electrodes are fabricated using vacuum thermal evaporation or electron beam evaporation, and the electrode materials include gold or nickel / gold stacks.

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