阅读说明：本技术 一种室温超短沟道硒化铂太赫兹探测器及制备方法 (Room-temperature ultra-short channel platinum selenide terahertz detector and preparation method thereof ) 是由 王林 郭万龙 郭程 陈效双 陆卫 于 2019-11-18 设计创作，主要内容包括：本发明公开了一种室温超短沟道硒化铂太赫兹探测器及制备方法。器件结构自下而上依次为：第一层是衬底、第二层是氧化层、第三层是硒化铂以及搭在硒化铂上的非对称的蝶形天线和天线两侧的金属电极。器件制备步骤是将机械剥离的硒化铂转移到氧化层上,用紫外光刻方法和倾角蒸镀工艺制备非对称的蝶形天线和金属电极,形成硒化铂太赫兹探测器。太赫兹光照射时,赛贝克电动势驱动硒化铂内载流子定向运动,实现室温快速的太赫兹的探测。该探测器具有高速、宽频、高响应、高稳定性等优点,可以在室温下对树叶进行无电离损伤成像,也可以对封装在纸袋中的金属钥匙透射成像,为实现室温太赫兹探测器广泛应用奠定基础。(The invention discloses a room-temperature ultra-short channel platinum selenide terahertz detector and a preparation method thereof. The device structure is from bottom to top: the first layer is a substrate, the second layer is an oxide layer, the third layer is platinum selenide, and an asymmetric butterfly antenna and metal electrodes on two sides of the antenna are lapped on the platinum selenide. The preparation method of the device comprises the steps of transferring the mechanically stripped platinum selenide onto an oxide layer, and preparing the asymmetric butterfly antenna and the metal electrode by using an ultraviolet lithography method and an inclination evaporation process to form the platinum selenide terahertz detector. When terahertz light is irradiated, seebeck electromotive force drives carriers in platinum selenide to move directionally, and rapid terahertz detection at room temperature is realized. The detector has the advantages of high speed, wide frequency, high response, high stability and the like, can perform non-ionization damage imaging on leaves at room temperature, can also perform transmission imaging on metal keys packaged in paper bags, and lays a foundation for realizing wide application of the room-temperature terahertz detector.)

1. The utility model provides a room temperature ultrashort channel platinum selenide terahertz detector, includes substrate (1), oxide layer (2), platinum selenide (3), chrome gold butterfly antenna (4), metal electrode one (5), metal electrode two (6) and titanium gold butterfly antenna (7), its characterized in that:

the structure of the detector is as follows from bottom to top: the first layer is a substrate (1), the second layer is an oxide layer (2), the third layer is platinum selenide (3), a chrome gold butterfly antenna (4) and a titanium gold butterfly antenna (7) which are lapped on the platinum selenide, and a first metal electrode (5) and a second metal electrode (6) which are connected with the antennas;

the substrate (1) is a high-resistance silicon substrate, and the resistivity is more than 10000 ohm-meter;

the oxide layer (2) is a silicon dioxide layer;

the thickness of the platinum selenide (3) is 30-50 nanometers;

the chrome-gold butterfly antenna (4) is provided with two metal layers, wherein the lower metal layer is chrome, and the upper metal layer is gold; the first metal electrode (5) and the second metal electrode (6) are composite metal electrodes, the lower layer metal is chromium, and the upper layer metal is gold;

the titanium butterfly antenna (7) is provided with two metal layers, wherein the lower metal layer is titanium, and the upper metal layer is gold.

2. A preparation method for preparing the room temperature ultrashort channel platinum selenide terahertz detector as claimed in claim 1, characterized by comprising the following steps:

1) transferring the platinum selenide (3) to the surface of the oxide layer (2) by a micromechanical stripping method;

2) preparing a first metal electrode (5) and a second metal electrode (6) of a chrome-gold butterfly antenna (4) by adopting an ultraviolet lithography technology and combining electron beam evaporation and a traditional stripping process;

3) and covering titanium gold on the chrome gold butterfly antenna and part of platinum selenide by adopting an inclined angle evaporation method to form an ultra-short channel and an asymmetric metal antenna.

Technical Field

The invention relates to a room-temperature ultra-short channel platinum selenide terahertz detector and a preparation method thereof, in particular to a method for forming an ultra-short channel and an asymmetric metal antenna structure by using an inclination evaporation method, realizing terahertz electric field enhancement by using an ultra-narrow slit positioned in the middle of an antenna, when terahertz irradiation is carried out, an asymmetric electrode generates seebeck electromotive force to drive a carrier to move directionally, a photovoltaic signal is generated, room-temperature detection of terahertz radiation is realized, terahertz nondestructive imaging of fresh leaves is carried out, and metal key transmission imaging packaged in an envelope is carried out.

Background

The frequency of Terahertz waves (THz) is generally considered to be between 0.1 and 10THz (wavelength of 3 mm to 30 μm), which is between millimeter waves and infrared rays. Terahertz research is a cross discipline that intersects electronics and photonics. In the past, the research on a high-power and stable-output solid terahertz source and a high-speed and high-sensitivity terahertz detector is difficult and serious, and the development and application of the terahertz technology are limited, which are often called as THz blanks (terahertz gaps).

The terahertz photon characteristics and application are as follows: (a) the terahertz photon energy (with the characteristic value of 4meV) is low, the transmission is good, and because the terahertz wave has very low photon energy, when penetrating through a substance, the terahertz wave is not easy to ionize; and because the terahertz photons have good transmission to a plurality of nonpolar molecules, the terahertz photons can be used for imaging or nondestructive detection of a human body, and compared with X-ray detection, the terahertz photons have greatly reduced damage to a living organism. (b) The characteristic of the fingerprint spectrum, namely the terahertz waveband is overlapped with the vibration and rotation characteristic frequencies of a plurality of macromolecules, so that a plurality of substances have obvious resonance absorption peaks in the terahertz waveband, and the characteristic of the fingerprint spectrum can be used for substance detection, such as drug detection, DNA detection and the like. (c) The terahertz wave has good stability of time domain frequency spectrum and higher signal-to-noise ratio than that of the Fourier transform infrared spectrum technology, so that the terahertz wave is very suitable for imaging application. (d) The terahertz wave band has good coherence and wide coverage range, and is a favorable alternative wave band for next generation wireless communication.

The application and breakthrough of the terahertz technology are realized, and one key point is to prepare a terahertz wave detector with high speed, high sensitivity, high stability and room temperature work, so that the development of a room temperature detector with high-efficiency photoelectric conversion becomes a core subject of the current terahertz detection and terahertz imaging research. At present, quantum well terahertz detection is difficult, mainly because the photon energy of terahertz is smaller than the energy of thermal disturbance, and the terahertz is easy to saturate; the detection efficiency of the method using plasmon over-damped oscillation in a field effect transistor is not sufficiently high. In a commercial terahertz wave detector, the response speed of the pyroelectric detector is relatively slow, and the response time is generally millisecond-level; bolometers generally require relatively low operating temperatures; the operating frequency of schottky diodes is in the sub-terahertz band and requires a very complex process.

The advent of two-dimensional materials provides a new alternative to terahertz detection. The composite material has the advantages of large surface area, few dangling bonds, adjustable band gap and the like, and is favored and widely concerned. The platinum selenide is a II-type dirac semimetal material and has the characteristics of high carrier mobility, adjustable band gap along with the change of the number of layers, strong stability, rich topological properties and the like. The material is combined with an asymmetric butterfly antenna with an ultra-narrow slit, so that the focusing enhancement and the efficient coupling and conversion of a terahertz electric field can be realized, and a good platform is provided for the research of a novel terahertz detector.

Disclosure of Invention

The invention provides a room-temperature ultra-short channel platinum selenide terahertz detector and a preparation method thereof, and realizes the application of a platinum selenide device in the fields of room-temperature terahertz sensitive detection, nondestructive transmission imaging and the like. The detector combines a platinum selenide material with an asymmetric butterfly antenna (bow-tie antenna) with an ultra-narrow slit, the detector utilizes the ultra-narrow slit positioned in the middle of the antenna to realize the enhancement of a terahertz electric field, and utilizes an asymmetric metal electrode to generate seebeck electromotive force to drive a current carrier to move directionally at room temperature, thereby generating a photovoltaic signal, realizing the sensitive detection of terahertz radiation, the lossless transmission imaging of fresh leaves and the transmission imaging of a metal key packaged in a paper bag.

The invention relates to a room temperature ultra-short channel platinum selenide terahertz detector and a preparation method thereof, wherein the structure of the detector is as follows from bottom to top: the first layer is a substrate 1, the second layer is an oxide layer 2, the third layer is platinum selenide 3, a chrome gold butterfly antenna 4 and a titanium gold butterfly antenna 7 which are lapped on the platinum selenide, and a first metal electrode 5 and a second metal electrode 6 which are connected with the antennas.

The substrate 1 is a high-resistance silicon substrate, and the resistivity is more than 10000 ohm.m;

the oxide layer 2 is silicon dioxide;

the thickness of the platinum selenide 3 is 30-50 nanometers;

in the chrome-gold butterfly antenna 4, the lower layer metal is chrome, and the upper layer metal is gold;

the first metal electrode 5 and the second metal electrode 6 are composite metal electrodes, the lower layer metal is chromium, and the upper layer metal is gold;

in the titanium butterfly antenna 7, the lower layer metal is titanium, and the upper layer metal is gold.

The invention relates to a room temperature ultra-short channel platinum selenide terahertz detector and a preparation method thereof, wherein the preparation method of the device comprises the following steps:

1) transferring platinum selenide 3 to the surface of the oxide layer 2 by a micro-mechanical stripping method;

2) preparing a chrome gold butterfly antenna 4, a first metal electrode 5 and a second metal electrode 6 by adopting an ultraviolet lithography technology and combining electron beam evaporation and a traditional stripping process;

3) and covering the chrome gold butterfly antenna and part of platinum selenide with titanium gold by adopting an inclined-angle evaporation technique (Tilt-angle evaporation technique) to form an ultra-short channel and an asymmetric metal antenna.

The invention has the advantages that:

1) the high-resistance silicon is used as the substrate, so that the reflection of the low-resistance silicon substrate to terahertz is effectively reduced, and the light absorption and photoelectric conversion efficiency of the detector are improved.

2) Platinum selenide is used as a conductive channel material, has the advantages of high carrier mobility, adjustable band gap, high stability and the like, and can realize broadband and high-speed terahertz detection.

3) The asymmetric butterfly antenna structure with the ultra-narrow slit is adopted, so that the focusing enhancement of the terahertz electric field is realized, and the photoelectric conversion capability of the device is improved.

4) The detector can realize nondestructive imaging of fresh leaves at room temperature, can also image metal keys packaged in envelopes, and provides a feasible exploration scheme for the wide application of room-temperature terahertz detectors.

Drawings

FIG. 1 is a schematic side view of a structural unit of a platinum selenide thin-layer terahertz detection device in the invention;

in the figure: the antenna comprises a substrate 1, an oxide layer 2, platinum selenide 3, a gold butterfly antenna with 4 chromium, a first metal electrode 5, a second metal electrode 6 and a gold butterfly antenna with 7 titanium.

FIG. 2 is a schematic diagram of an experimental device for testing a platinum selenide terahertz detection device;

FIG. 3 is a response waveform diagram of a platinum selenide terahertz detector at room temperature at a chopping frequency of 1kHz and a working frequency of 0.12 THz;

FIG. 4 is a response waveform diagram of a platinum selenide terahertz detector at room temperature under the working frequency of 1kHz and 0.29 THz;

FIG. 5 is a response diagram of a platinum selenide terahertz detector in the polarization direction of terahertz waves;

FIG. 6 is a response diagram of a platinum selenide terahertz detector placed in air for half a year;

fig. 7 is a graph of the raman response of platinum selenide material in a platinum selenide terahertz detector channel over time.

The specific implementation mode is as follows:

the following detailed description of embodiments of the invention refers to the accompanying drawings in which:

the invention develops an ultra-ultrashort channel room temperature platinum selenide terahertz detector. The detector adopts an asymmetric butterfly antenna structure with an ultra-narrow slit. When terahertz light is irradiated, seebeck electromotive force drives carriers in platinum selenide to move directionally, and rapid terahertz detection at room temperature is realized. The detector has the advantages of high speed, wide frequency, high response, high stability and the like, can perform non-ionization damage imaging on leaves at room temperature, and can also perform transmission imaging on a metal key packaged in a paper bag.

The method comprises the following specific steps:

1. substrate selection

High-resistance silicon is selected as a substrate, and the resistivity is more than 10000 ohm.

2. Thermal oxidation method for preparing oxide layer on substrate

3. Platinum selenide preparation and transfer

The platinum selenide is transferred onto the oxide layer by a mechanical stripping method, and the thickness of the platinum selenide is 30 nanometers to 50 nanometers.

4. Preparation of platinum selenide antenna and electrode

Preparing a chrome-gold butterfly antenna and a metal electrode by adopting an ultraviolet lithography technology and combining an electron beam evaporation technology, wherein the lower layer metal is chrome, and the upper layer metal is gold; and stripping the metal film by combining the traditional stripping process to obtain the chrome gold antenna and the composite metal electrode.

5. And evaporating a titanium electrode layer on the prepared antenna by using an inclined angle evaporation method and covering part of platinum selenide to prepare the titanium electrode and form an ultra-short channel at the same time.

6. Photoelectric characterization and imaging experiments of the platinum selenide terahertz detector. As shown in FIG. 3, the terahertz photoelectric characterization and imaging system is built by a laboratory, the terahertz source is composed of a microwave source, a frequency multiplier and an amplifier, and the frequency range is 0.02-0.3 THz. Terahertz radiation modulated by electromagnetic chopping is focused on a detection device through an off-axis parabolic mirror, a photocurrent signal generated by the detection device is amplified through a preamplifier (SR570), then is input into an oscilloscope to display waveform, and is simultaneously input into a phase-locked amplifier (SR830) to extract signals, and the whole process is controlled by a computer through an integrated software system. The test result shows that:

a) when the thickness of platinum selenide is 30 nm, the channel length is 100 nm. Under the irradiation of terahertz waves with the power density of 1 milliwatt per square centimeter, the photoelectric current of 100 nanoamperes can be realized.

b) When the thickness of platinum selenide is 40 nm, the channel length is 100 nm. Under the irradiation of terahertz waves with the power density of 1 milliwatt per square centimeter, 120 nanoamperes of photocurrent can be realized.

c) When the thickness of platinum selenide is 50 nm, the channel length is 100 nm. Under the irradiation of terahertz waves with the power density of 1 milliwatt per square centimeter, 200 nanoamperes of photocurrent can be realized.

When the parameters of the detector structure are changed within a certain range, the platinum selenide room-temperature terahertz wave detector can well detect terahertz waves, and test results show that the device has good polarization characteristics, the response time of the device can reach 1 microsecond, the response rate can reach 200V/W at 0.29THz, and the noise equivalent power is lower than 100pW/Hz^0.5And the control of response amplitude under bias voltage is preliminarily realized, and the terahertz wave can be effectively detected at room temperature. The device can realize clear imaging of fresh leaves at room temperature, can also realize transmission imaging of the metal key packaged in the envelope, and has wide application value in the field of terahertz detection and imaging.