CN210272401U

CN210272401U - Room temperature black phosphorus terahertz detector

Info

Publication number: CN210272401U
Application number: CN201921070803.9U
Authority: CN
Inventors: 王林; 郭万龙; 郭程; 陈效双; 陆卫
Original assignee: Shanghai Institute of Technical Physics of CAS
Current assignee: Shanghai Institute of Technical Physics of CAS
Priority date: 2019-07-10
Filing date: 2019-07-10
Publication date: 2020-04-07
Anticipated expiration: 2029-07-10

Abstract

The patent discloses a room temperature black phosphorus terahertz detector. The device structure is from bottom to top: the first layer is an intrinsic silicon substrate, the second layer is an oxide layer, the third layer is black phosphorus, and an asymmetric butterfly antenna and metal electrodes on two sides of the antenna are lapped on the black phosphorus. The preparation method of the device comprises the steps of transferring the black phosphorus which is mechanically stripped onto a substrate, and preparing an asymmetric butterfly antenna and a metal electrode by combining an ultraviolet lithography or electron beam exposure method and an inclination evaporation process to form the black phosphorus terahertz detector. When the terahertz light irradiates the device, current carriers in the black phosphorus move in a single direction under the drive of the seebeck electromotive force to generate response signals and realize rapid terahertz detection at room temperature. The detector has the characteristics of high speed, wide frequency, high response, high integration and the like, can perform nondestructive active imaging on fresh leaves at room temperature, and lays a foundation for realizing large-scale application of the room-temperature terahertz detector.

Description

Room temperature black phosphorus terahertz detector

Technical Field

The utility model relates to a room temperature black phosphorus terahertz detector specifically indicates to utilize inclination evaporation coating technique to form short channel and asymmetric metal electrode structure, utilizes the slit that is located in the middle of the antenna to realize the enhancement of terahertz electric field, and under terahertz illumination, utilizes asymmetric metal antenna to produce seebeck electromotive force and drive carrier unidirectional motion, produces photovoltaic signal, realizes detecting the room temperature of terahertz radiation and the terahertz imaging to fresh leaf.

Background

Terahertz waves (THz) refer to electromagnetic waves with the frequency of 0.1-10 THz (the wavelength is 3-30 microns), and the long wave band direction is millimeter waves (sub-millimeter waves) and the short wave band direction is infrared rays. For a long time, due to the lack of a high-power and stable-output terahertz source and a high-speed and high-sensitivity terahertz detector, the development and wide application of terahertz technology are limited, and therefore, a so-called THz blank (terahertz gap) is formed.

The terahertz photon characteristics and application are as follows: (a) the terahertz wave has low quantum energy (the characteristic value is 4meV), and because the terahertz wave has low photon energy, when penetrating through a substance, the terahertz wave is not easy to ionize, so that the terahertz wave can be used for imaging or nondestructive detection of a human body, and the defect that the living body is damaged by X-ray detection is overcome. (b) The fingerprint spectrum features that the vibration and rotation frequencies of many biomacromolecules are in the terahertz wave band, so that the terahertz wave shows strong absorption and resonance, which enables the biomacromolecules to be identified, 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) Terahertz waves have high permeability to many substances, and thus show powerful functions and effects in the diagnosis and treatment of cancer, safety inspection, and the like.

The application and breakthrough of the terahertz technology are realized, one key technology is to realize the terahertz wave detection and imaging with high speed, high sensitivity and room temperature working, and the room temperature detection device capable of enhancing the interaction capacity of light and the device and further enhancing the photoelectric response capacity of the terahertz wave is required to be developed. However, the traditional method relying on quantum well intersubband transition has great difficulty in terahertz detection, mainly because the terahertz photon energy is smaller than the thermal disturbance energy and can easily reach saturation; the response rate that can be achieved with the field effect transistor plasmon over-damped oscillation method is still relatively low. In commercial terahertz wave detectors with more applications, a bolometer needs to work under a low-temperature condition; the operating frequency of the schottky diode is less than 1 terahertz and a relatively complex preparation process is required; the pyroelectric detector has a slow response speed, typically on the order of milliseconds. Therefore, it is urgent to search for new semiconductor materials and new functional structures to realize terahertz detection, and the terahertz detection is widely regarded. In the aspect of new materials, the black phosphorus material has the advantages of high carrier mobility, in-plane anisotropy, simple and convenient material growth mode, adjustable topological property under the action of a vertical electric field and the like; in the aspect of a new structure, the asymmetric butterfly-shaped antenna with the slit can realize the enhancement and the high-efficiency coupling of the terahertz electric field. The combination of the two provides a good platform for the research of novel terahertz photoelectric detectors.

Disclosure of Invention

The patent provides a room temperature black phosphorus terahertz detector, has realized the application of black phosphorus device in room temperature terahertz detection and nondestructive imaging field.

According to the detector, a black phosphorus material is combined with an asymmetric butterfly antenna (bow-tie antenna) with a slit, the detector utilizes the slit positioned in the middle of the antenna to realize terahertz electric field enhancement, and utilizes an asymmetric metal electrode to generate seebeck electromotive force to drive a carrier to move in a single direction at room temperature, so that a photovoltaic signal is generated, and terahertz radiation detection and nondestructive imaging of fresh leaves are realized.

The patent refers to a room temperature black phosphorus terahertz detector and a preparation method thereof, the structure of the detector is from bottom to top: the first layer is an intrinsic silicon substrate 1, the second layer is an oxide layer 2, the third layer is black phosphorus 3, and a chromium gold butterfly antenna 4 and a titanium gold butterfly antenna 7 which are lapped on the black phosphorus, a first metal electrode 5 and a second metal electrode 6 which are connected with the antennas.

The intrinsic silicon substrate 1 is an intrinsic silicon substrate;

the oxide layer 2 is silicon dioxide;

the thickness of the black phosphorus 3 is 10-30 nanometers;

in the chromium-gold butterfly antenna 4, the lower layer metal is chromium, 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;

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

The patent refers to a room temperature black phosphorus terahertz detector and a preparation method thereof, wherein the preparation of the device comprises the following steps:

1) preparing an oxide layer 2 on an intrinsic silicon substrate 1 by a thermal oxidation method;

2) transferring the black phosphorus 3 to the surface of the oxide layer 2 by a micro-mechanical lift-off method;

3) preparing a chromium-gold butterfly antenna 4, a first metal electrode 5 and a second metal electrode 6 by adopting an ultraviolet lithography technology or an electron beam exposure technology and combining a thermal evaporation and a traditional stripping process;

4) and covering titanium on the chromium gold butterfly antenna and part of black phosphorus by adopting a tilted-angle evaporation technology (tilted-angle evaporation technology) to form a short channel and an asymmetric metal antenna.

The advantage of this patent lies in:

1) the intrinsic silicon is used as the substrate, so that the reflection of the highly doped silicon substrate to the terahertz is greatly reduced, the absorptivity of the device is improved, and the terahertz response rate of the device is further improved.

2) The black phosphorus is used as a conductive channel material, has the advantages of high carrier mobility, in-plane anisotropy, adjustable band gap and the like, and can realize broadband and high-speed terahertz detection.

3) By adopting a butterfly antenna structure with a slit, the enhancement of a terahertz electric field is realized and the photoelectric conversion capability of the device is improved.

4) An asymmetric metal antenna is adopted, Seebeck electromotive force is generated under the irradiation of terahertz light, a carrier is driven to move in a single direction to generate photoelectric response, and sensitive terahertz detection is realized.

5) The detector can realize nondestructive imaging of fresh leaves, and lays a foundation for realizing large-scale application of the room-temperature terahertz detector.

Drawings

FIG. 1 is a schematic side view of a structural unit of a black phosphorus thin-layer terahertz detection device;

in the figure: 1 intrinsic silicon substrate, 2 oxide layer, 3 black phosphorus, 4 chromium gold butterfly antenna, 5 metal electrode I, 6 metal electrode II and 7 titanium gold butterfly antenna.

FIG. 2 is a schematic structural top view of a black phosphorus terahertz detection device;

FIG. 3 is a schematic diagram of an experimental device for testing a black phosphorus terahertz detection device;

FIG. 4 is a response waveform diagram of the black phosphorus terahertz detector at a working frequency of 1kHz and 0.12THz at room temperature;

FIG. 5 is a response waveform diagram of the black phosphorus terahertz detector at a working frequency of 1kHz and 0.27THz at room temperature;

FIG. 6 is a response diagram of a terahertz wave polarization direction of a black phosphorus terahertz detector;

fig. 7 is a response diagram of a black phosphorus terahertz detector under near-infrared light assisted detection.

The specific implementation mode is as follows:

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

this patent has developed a room temperature black phosphorus terahertz detector. The detector adopts an asymmetric butterfly antenna structure with a slit. Under the irradiation of terahertz light, the seebeck electromotive force caused by the asymmetric electrodes drives the carriers to move in a single direction, so that photovoltaic signals are generated, and the detection of terahertz radiation and the nondestructive imaging of fresh leaves are realized.

The method comprises the following specific steps:

1. substrate selection

Intrinsic silicon is selected as the substrate.

2. Oxide layer preparation

Silicon dioxide is oxidized on the surface of the silicon substrate by a thermal oxidation method.

3. Black phosphorus preparation and transfer

Transfer of black phosphorus to SiO by mechanical stripping₂On the Si substrate, the thickness of black phosphorus is 10 to 30 nanometers;

4. preparation of black phosphorus antenna and electrode

Preparing a chromium-gold butterfly antenna and a metal electrode by adopting an ultraviolet lithography technology or an electron beam exposure technology and combining a thermal evaporation technology, wherein the lower layer metal is chromium, 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 technology and covering part of black phosphorus, and preparing the titanium electrode and simultaneously shortening the length of a device channel.

6. And carrying out photoelectric response test and imaging on the prepared black phosphorus terahertz detector. As shown in FIG. 3, terahertz radiation of 0.02-0.3THz is focused through an off-axis parabolic mirror and then irradiates on a detection device, a photocurrent signal generated by the detection device is amplified through a preamplifier (SR570) and is respectively input into an oscilloscope and a phase-locked amplifier (SR830), and in addition, a reference signal of chopper frequency of a chopper (SR430) is also required to be respectively input into the oscilloscope and the phase-locked amplifier, so that terahertz response waveform retention and responsivity recording can be guaranteed. The device shows ultrahigh response rate and rapid detection capability in the test process.

a) When the thickness of the black phosphorus is 10 nm, the channel length is 70 nm. Under the irradiation of terahertz waves with the power density of 100 microwatts per square millimeter, 50 nanoamperes of photocurrent can be realized.

b) When the thickness of the black phosphorus is 20 nm, the channel length is 70 nm. Under the irradiation of terahertz waves with the power density of 100 microwatts per square millimeter, 80 nanoamperes of photocurrent can be realized.

c) When the thickness of the black phosphorus is 30 nm, the channel length is 70 nm. Under the irradiation of terahertz waves with the power density of 100 microwatts per square millimeter, the photocurrent of 100 nanoamperes can be realized.

When the parameters of the detector structure in the patent are changed in a certain range, the black phosphorus room temperature terahertz wave detector can well detect terahertz waves, test results show that the response time of the device can reach 0.8 microsecond, the response rate can reach 2000V/W at 0.12THz, and the noise equivalent power reaches 10pW/Hz^0.5And the change 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, and has wide application value in the field of terahertz detection and imaging.

Claims

1. The utility model provides a room temperature black phosphorus terahertz detector, includes intrinsic silicon substrate (1), oxide layer (2), black phosphorus (3), chromium gold butterfly shape antenna (4), metal electrode one (5), two (6) of metal electrode and titanium gold butterfly shape antenna (7), its characterized in that:

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

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

the thickness of the black phosphorus (3) is 10-30 nanometers;

the chromium-gold butterfly antenna (4) is provided with two metal layers, wherein the lower metal layer is chromium, 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.