Solid hydrogen reduction strontium titanate photo-thermal electric detector and preparation method thereof

Abstract

The invention discloses a solid hydrogen reduction strontium titanate photo-thermoelectric detector and a preparation method thereof, which are characterized in that efficient absorption of visible to infrared multi-band light is realized by utilizing a photo-thermoelectric effect, and the thermoelectric performance of the device is further optimized. The strontium titanate material is cut into a specified device size, and the surface of the strontium titanate material is finely polished. And performing solid hydrogen reduction treatment on the cut strontium titanate material by using a high-temperature tubular furnace to improve the conductivity of the strontium titanate material. The method comprises the following steps: uniformly coating conductive silver adhesives at two ends of the material to serve as electrical test electrodes, fixing one end of the strontium titanate material on an aluminum oxide substrate by using heat-conducting adhesives with high heat conductivity, and connecting the substrate with a constant-temperature hot pool. The solid hydrogen reduction strontium titanate photothermoelectric detector has the advantages of high conductivity, high Seebeck coefficient, small material damage, wide spectrum absorption range, simple structure, easy large-scale preparation, high repeatability and the like, and can meet the detection requirements of visible light and infrared light bands.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detection devices, and in particular to a solid-state hydrogen-reduced strontium titanate photothermoelectric detector and a preparation method thereof, which can realize high-performance detection of visible and infrared multi-band light based on the photothermoelectric effect. Background Art

[0002] Photodetectors can convert optical signals into electrical signals. They are key components of detection systems and have important applications in communications, medical imaging, environmental monitoring, astronomical observation, security monitoring, industrial automatic control, smart homes, and smart driving. According to the working principle of photodetectors, they can be divided into photon detectors and photothermal detectors. Photon detectors, based on the photoelectric effect, directly generate photogenerated carriers after absorbing photons, changing the electrical properties of the detector. Photon detectors have the advantages of high detection rate and fast response speed, but their detection wavelength is limited by the energy band width of semiconductor materials, the absorption rate of long-wavelength light is low, the detection band is short, and usually requires a complex low-temperature working environment. Photothermal detectors, based on the photothermoelectric effect, first convert photon energy into thermal energy after absorbing photons, causing changes in the temperature of the detector, and then changing the electrical properties of the detector. Photothermal detectors have a slow response speed and a low detection rate. Photon detectors also have many advantages. They detect light through energy changes, so their absorption band is very wide and is not limited by the material band structure. Their response rate is little affected by the detection wavelength, and they can detect infrared and terahertz light with very long wavelengths. In addition, they do not require a special low-temperature working environment, which greatly reduces the operating cost of the detector and broadens the application scenarios of the detector.

[0003] Strontium titanate is a wide bandgap semiconductor material with a typical perovskite structure (ABo 3 ), where the A position is a strontium ion (Sr 2+ ), the B position is titanium ion (Ti 4+ ), the lattice constant is approximately It has a cubic symmetrical structure at room temperature and has a high light absorption coefficient, making it suitable for the development of optoelectronic devices. It has good thermoelectric properties at room temperature, but its bandgap is about 3.2eV, which makes its conductivity very low at room temperature. Through solid-state hydrogen reduction technology, the electrical properties of strontium titanate materials can be changed, and its conductivity can be improved to meet the requirements for the preparation of high-performance detectors. In addition, this reduction technology is safe and reliable, has little environmental pollution, and can be mass-produced. A multi-band detector is an optoelectronic device that can operate and obtain information in multiple spectral bands (such as ultraviolet, visible light, infrared, and terahertz). Compared with a single-band detector, it can capture the spectral characteristics of the target more comprehensively. In the detection of different bands, the contrast and absorption characteristics of the target and background information will be significantly different. The multi-band detector can obtain more comprehensive information, thereby improving the accuracy of signal recognition, flexibly switching working modes in complex scenes, and responding to various task requirements. Summary of the invention

[0004] The present invention provides a solid-state hydrogen-reduced strontium titanate photothermoelectric detector, which solves the problem of low conductivity of intrinsic strontium titanate materials during photoelectric detection, and realizes high-performance detection of visible and infrared multi-band light at room temperature. The solid-state hydrogen-reduced strontium titanate photothermoelectric detector comprises strontium titanate, a metal front electrode, a metal rear electrode, a thermally conductive adhesive and a thermally conductive substrate, and is characterized in that:

[0005] The solid-state hydrogen-reduced strontium titanate photothermoelectric detector adopts a semi-suspended structure, that is, the metal rear electrode end of the detector is fixed on the thermally conductive substrate by thermally conductive adhesive, and the rest of the detector such as the middle and metal front electrode is suspended, thereby increasing the temperature gradient inside the device.

[0006] The metal front electrode and the metal rear electrode are located at two ends of strontium titanate.

[0007] The metal rear electrode, strontium titanate, thermal conductive adhesive and thermal conductive substrate are stacked vertically in sequence.

[0008] The strontium titanate is strontium titanate after solid-state hydrogen reduction treatment, the reduction temperature is 350-600°C, the reduction time is 0.5-8h, its length range is 8-12mm, the width range is 1-3mm, the thickness range is 100-500μm, the Seebeck coefficient range is 100-800μV / K, the electrical conductivity range is 3-80S / cm, and the thermal conductivity range is 3-30W / (m·K).

[0009] The metal front electrode and the metal rear electrode are made of conductive silver paste, covering both ends of strontium titanate, with a width of 1.5 mm and a thickness of 100-500 μm.

[0010] The heat-conducting substrate is made of aluminum oxide with high thermal conductivity, connected to a constant-temperature heat pool, has a size of 5 mm×5 mm, and a thickness of 100-200 μm.

[0011] A method for preparing the detector comprises the following steps:

[0012] ① First, use a cutting machine to cut the intrinsic strontium titanate material into the required size of the device, then thin and polish its surface, and then clean the surface of the intrinsic strontium titanate material with acetone, ethanol and deionized water;

[0013] ② Solid-state hydrogen reduction of intrinsic strontium titanate is carried out in a tube furnace to obtain strontium titanate with high conductivity, and then the surface is cleaned twice;

[0014] ③ Use conductive silver glue to make metal front electrode and metal back electrode on strontium titanate with high conductivity and high Seebeck coefficient;

[0015] ④Finally, use a thermally conductive adhesive with high thermal conductivity to fix the metal rear electrode end of the device on the aluminum oxide thermal conductive substrate.

[0016] The principle of the present invention is:

[0017] When light is irradiated on the metal front electrode end of the solid-state hydrogen-reduced strontium titanate photodetector, the temperature of one end of the device rises, forming a temperature difference with the other end, and the temperature difference is converted into photovoltage through the thermoelectric properties of the strontium titanate material.

[0018] The advantages of the present invention are:

[0019] 1. Solid-state hydrogen reduction technology is simple to operate, environmentally friendly, safe and reliable, low-cost, and easy to mass produce.

[0020] 2. Strontium titanate material has a high Seebeck coefficient, good thermoelectric properties, and strong light detection capabilities.

[0021] 3. The device has a simple structure, good repeatability, is easy to integrate, and can operate with low power consumption under zero bias. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the detector of the present invention.

[0023] Figure 2 It is a cross-sectional schematic diagram of the detector of the present invention.

[0024] Figure 3 The present invention is a flow chart of the preparation process of the detector.

[0025] Figure 4 This is a response performance diagram of the detector of the present invention in the mid-wave infrared band of 3.85μm.

[0026] Figure 5 This is a response performance diagram of the detector of the present invention in the near-infrared band of 1550nm.

[0027] Figure 6 This is a graph showing the response performance of the detector of the present invention in the visible light band of 637 nm. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings:

[0029] The present invention has developed a solid-state hydrogen-reduced strontium titanate photothermoelectric detector. The solid-state hydrogen-reduced strontium titanate thermoelectric material generates a temperature gradient under light irradiation, and the temperature gradient drives the directional movement of carriers inside the device to generate photoinduced electromotive force, thereby achieving high-performance detection of multi-band light.

[0030] Example 1

[0031] In this embodiment, strontium titanate is selected as the thermoelectric material, and the specific steps are as follows:

[0032] ① Cut a 10mm×3mm×0.5mm sample from the block strontium titanate material, then polish its surface, and then use acetone, ethanol, and deionized water to perform organic cleaning on its surface;

[0033] ② The intrinsic strontium titanate is subjected to solid-state hydrogen reduction treatment at 400°C in a tube furnace for 2 hours to obtain strontium titanate with high electrical conductivity, and then its surface is cleaned twice;

[0034] ③Using conductive silver glue, evenly coating both ends of the solid hydrogen-reduced strontium titanate to make a metal front electrode and a metal back electrode;

[0035] ④ Use thermal conductive adhesive with high thermal conductivity to fix one end of the metal rear electrode of the device on the thermal conductive substrate.

[0036] Example 2

[0037] In this embodiment, strontium titanate is selected as the thermoelectric material, and the specific steps are as follows:

[0038] ① Cut a 10mm×3mm×0.5mm sample from the block strontium titanate material, then polish its surface, and then use acetone, ethanol, and deionized water to perform organic cleaning on its surface;

[0039] ② The intrinsic strontium titanate is subjected to solid-state hydrogen reduction treatment at 450°C in a tube furnace for 1 hour to improve the conductivity of the strontium titanate, and then the surface is subjected to secondary organic cleaning;

[0040] ③Using conductive silver glue, evenly coating both ends of the strontium titanate to make a metal front electrode and a metal back electrode;

[0041] ④ Use thermal conductive adhesive to fix one end of the metal rear electrode of the device on the aluminum oxide thermal conductive substrate.

[0042] Example 3

[0043] In this embodiment, strontium titanate is selected as the thermoelectric material, and the specific steps are as follows:

[0044] ① Cut a 10mm×3mm×0.5mm sample from the block strontium titanate material, then thin it to 0.2mm, polish its surface, and then use acetone, ethanol, and deionized water to perform organic cleaning on its surface;

[0045] ② The intrinsic strontium titanate is subjected to solid-state hydrogen reduction in a tube furnace at 400°C for 2 hours to obtain strontium titanate with high electrical conductivity, and then its surface is cleaned twice;

[0046] ③ Using conductive silver glue, evenly apply the two ends of the strontium titanate to prepare a metal front electrode and a metal back electrode;

[0047] ④ Use thermal conductive adhesive to fix the metal rear electrode end of the device on the thermal conductive substrate.

Claims

1. A solid-state hydrogen-reduced strontium titanate photothermoelectric detector, comprising strontium titanate (1), a metal front electrode (2), a metal rear electrode (3), a thermally conductive adhesive (4) and a thermally conductive substrate (5), characterized in that: The solid-state hydrogen-reduced strontium titanate photothermoelectric detector adopts a semi-suspended structure, that is, the metal rear electrode (3) end of the detector is fixed on the thermal conductive substrate (5) through a thermal conductive adhesive (4), and the middle of the detector and the metal front electrode (2) and other parts are in a suspended state, thereby increasing the temperature gradient inside the device; The metal front electrode (2) and the metal rear electrode (3) are located at two ends of the strontium titanate (1); The metal rear electrode (3), strontium titanate (1), thermal conductive adhesive (4) and thermal conductive substrate (5) are stacked vertically in sequence.

2. The solid-state hydrogen-reduced strontium titanate photothermoelectric detector according to claim 1, characterized in that: The strontium titanate (1) is strontium titanate after solid-state hydrogen reduction treatment, the reduction temperature is 350-600°C, the reduction time is 0.5-8h, its length range is 8-12mm, the width range is 1-3mm, the thickness range is 100-500μm, the Seebeck coefficient range is 100-800μV / K, the electrical conductivity range is 3-80S / cm, and the thermal conductivity range is 3-30W / (mK).

3. The solid-state hydrogen-reduced strontium titanate photothermoelectric detector according to claim 1, characterized in that: The metal front electrode (2) and the metal rear electrode (3) are conductive silver paste with a width of 1.5 mm and a thickness of 100-500 μm, covering both ends of the strontium titanate (1).

4. The solid-state hydrogen-reduced strontium titanate photothermoelectric detector according to claim 1, characterized in that: The heat-conducting substrate (5) is aluminum oxide with high thermal conductivity, has a size of 5 mm×5 mm, a thickness of 100-200 μm, and is connected to a constant temperature heat pool.

5. A method for preparing the solid-state hydrogen-reduced strontium titanate photothermoelectric detector as claimed in claim 1, characterized in that The steps include: ① Cutting the intrinsic strontium titanate (1) material into the required size of the device through a semiconductor cutting process, thinning and polishing the material, and then using acetone, ethanol and deionized water to perform organic cleaning on the material to maintain its wafer-level cleanliness; ② Using a high-temperature tube furnace to perform solid-state hydrogen reduction treatment on the intrinsic strontium titanate (1) material to improve the electrical properties of the material, and then performing secondary cleaning on its surface; ③ Using conductive silver glue, a metal front electrode (2) and a metal back electrode (3) are made at both ends of the strontium titanate (1) after solid-state hydrogen reduction treatment; ④ Using a thermal conductive adhesive (4) to fix one end of the metal rear electrode (3) on the thermal conductive substrate (5) to achieve a semi-suspension effect, thus completing the preparation of the device.

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