CN110828604A - A tunable room temperature black arsenic phosphorus terahertz detector and preparation method - Google Patents

Abstract

The invention discloses an adjustable room-temperature black arsenic phosphorus 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 black arsenic phosphorus, a butterfly antenna lapped on the black arsenic phosphorus, a metal electrode connected with the antenna, the third layer is a dielectric layer, and the fourth layer is a grid. The preparation method of the terahertz detector comprises the steps of transferring black arsenic phosphorus onto a substrate by using a mechanical stripping method, preparing a butterfly antenna and a metal electrode by using electron beam exposure and electron beam deposition technologies, growing a gate dielectric layer by using an atomic layer deposition technology, and preparing a gate by using the electron beam exposure and electron beam deposition technologies to form the terahertz detector. The working principle of the terahertz frequency mixing antenna is that a high-local-area and enhanced terahertz frequency mixing electric field is realized through the asymmetric high-efficiency terahertz antenna, and a response signal is generated. The detector has the characteristics of high speed, wide frequency, high sensitivity and the like, can realize double regulation and control of source-drain bias voltage and gate voltage, and provides a prototype device for realizing large-scale application of the room-temperature terahertz detector.

Description

A tunable room temperature black arsenic phosphorus terahertz detector and preparation method

technical field

The invention relates to a controllable room temperature black arsenic phosphorus terahertz detector and a preparation method, in particular to the preparation of field effect transistors by combining black arsenic phosphorus materials and butterfly antennas, and utilizing black arsenic phosphorus with adjustable band gap and carrier The characteristics of high mobility and in-plane anisotropy achieve fast response, and the butterfly antenna is used to achieve efficient coupling of terahertz electric fields, thereby achieving high response rate. It works by generating a response signal through a highly localized and enhanced terahertz mixing electric field via an asymmetric high-efficiency terahertz antenna. The detector has the characteristics of high speed, wide frequency and high responsivity, and can realize dual regulation of source-drain bias voltage and gate voltage, laying a foundation for the large-scale application of room temperature terahertz detectors.

Background technique

Terahertz waves have a frequency range of 0.1THz to 10THz, a wavelength range of 3 mm to 30 microns, and a photon energy characteristic value of 4 millielectron volts. This characteristic energy range matches the vibrational and rotational energies of the molecule and is much smaller than the band gap of common semiconductors. The characteristics of terahertz waves in terms of propagation, scattering, and absorption are quite different from those of visible light, infrared, and microwaves, providing a great space for spectroscopy, imaging, and communications. Terahertz technology is located at the intersection of electronics and photonics. The integration and development of these two disciplines has greatly improved the level of terahertz technology. However, the current research and development of terahertz is still in its infancy, and high-power, high-stability terahertz sources, high-sensitivity, wide-spectrum terahertz detectors and high-speed, high-efficiency terahertz modulators are still relatively scarce. It is called "THz Gap".

The unique position of terahertz waves in the electromagnetic spectrum determines that it has many special properties that other bands do not have: (1) The photon energy of terahertz radiation is generally only millielectron volts, which is far lower than the chemical bond energy of common substances, Therefore, terahertz waves can overcome the ionization damage of X-rays to many substances, and are suitable for security inspections in public places such as airports and stations. (2) The intrinsic vibration frequencies of many substances are in the terahertz band. These substances have the characteristics of terahertz fingerprints, which contain rich physical and chemical information, and can be used to identify and test substances by using terahertz waves. (3) Terahertz radiation has strong penetrating ability and can be used for quality monitoring and perspective imaging of non-transparent objects. (4) Terahertz waves have large bandwidth, high wireless transmission rate, low background noise and are not easily interfered, so they have great application potential in the field of wireless communication. In a word, terahertz waves are between microwave and infrared in the electromagnetic spectrum, and have many excellent characteristics. They have broad application prospects in the fields of security inspection, material identification, medicine, non-destructive imaging and wireless communication. Therefore, the development of terahertz waves The research of detection technology is of great significance.

The development of high-speed, high-sensitivity, and room-temperature terahertz detection devices is an important breakthrough in the realization of terahertz technology. Improving the coupling ability between light and devices and the photoelectric conversion efficiency is a key issue in terahertz detection. Current commercial terahertz detectors include pyroelectric terahertz detectors, thermal radiometers, and Schottky diodes. Usually, the response speed of pyroelectric detectors is relatively slow; the working frequency of Schottky diodes is relatively low, and the process is complicated; the thermal radiation meter needs to work at low temperature. In addition, quantum well terahertz detectors are easily affected by thermal disturbances; the quantum efficiency of field effect transistor terahertz detectors is still relatively low. Therefore, developing new materials and exploring new principles to realize terahertz detection has become a hot spot in the field of terahertz detection and has received extensive attention. The black arsenic phosphorus material has the characteristics of adjustable band gap, large electron mobility, in-plane anisotropy, and simple growth process; the asymmetric butterfly antenna can realize efficient coupling to the terahertz electric field. The combination of the two provides a new alternative for developing new terahertz detection technologies.

SUMMARY OF THE INVENTION

The invention provides a regulated room temperature black arsenic phosphorus terahertz detector and a preparation method, which realizes fast and high response rate room temperature terahertz detection. It works by generating a response signal through a highly localized and enhanced terahertz mixing electric field via an asymmetric high-efficiency terahertz antenna. The detector has the advantages of high speed, wide frequency and high sensitivity, and can realize dual regulation of source-drain bias voltage and gate voltage, laying a foundation for the large-scale application of room temperature terahertz detectors.

The present invention refers to a controllable room temperature black arsenic phosphorus terahertz detector and a preparation method. The structure of the detector from bottom to top is: the first layer is a substrate 1, the second layer is black arsenic phosphorus 2, and The butterfly antenna 3 mounted on the black arsenic phosphorus and the source electrode 4 and the drain electrode 5 connected to the antenna, the third layer is the dielectric layer 6, and the fourth layer is the gate electrode 7;

Described substrate 1 is intrinsic silicon and silicon dioxide covered on it;

The black arsenic phosphorus 2 is multilayer black arsenic phosphorus, with a thickness of 20-40 nanometers;

The butterfly antenna 3, the source electrode 4 and the drain electrode 5 have two metal layers, the lower layer metal is titanium, and the upper layer metal is gold;

The dielectric layer is hafnium oxide;

The gate 7 has two metal layers, the lower metal is titanium, and the upper metal is gold.

The present invention refers to a controllable room temperature black arsenic phosphorus terahertz detector and a preparation method, and the preparation of the device comprises the following steps:

1) silicon dioxide is prepared on intrinsic silicon by thermal oxidation method as substrate 1;

2) Prepare and transfer the black arsenic phosphorus 2 to the surface of the substrate 1 by a mechanical lift-off method;

3) The source electrode 4 and the drain electrode 5 of the butterfly antenna 3 are prepared by using electron beam exposure technology, combined with electron beam deposition and traditional stripping process;

4) using the atomic layer deposition process to grow the dielectric layer 6;

5) The gate electrode 7 is prepared on the dielectric layer 6 by electron beam exposure and electron beam deposition technology, and the preparation of a controllable room temperature black arsenic phosphorus terahertz detector is completed.

The advantages of the patent of the present invention are:

1) The use of intrinsic silicon as the substrate significantly reduces the reflection of the substrate on terahertz, and improves the optoelectronic coupling efficiency and response sensitivity of the device.

2) Using black arsenic phosphorus as the conductive channel material, the black arsenic phosphorus material has the advantages of adjustable band gap, high electron mobility, in-plane anisotropy, and low growth cost, and can be used for broadband and high-speed terahertz detection.

3) By adopting the butterfly antenna structure, the local enhancement of the terahertz electric field is realized, the coupling ability of the terahertz wave and the detector is improved, and the photoelectric conversion efficiency and detection rate of the detector are enhanced.

Description of drawings

Fig. 1 is the side view schematic diagram of the adjustable room temperature black arsenic phosphorus terahertz detector of the present invention;

In the picture: 1 silicon substrate, 2 black arsenic phosphorus, 3 butterfly antenna, 4 source, 5 drain, 6 dielectric layer, 7 gate.

Fig. 2 is a schematic diagram of the experimental setup for the test of the adjustable room temperature black arsenic phosphorus terahertz detector;

Figure 3 shows the response waveforms of the adjustable room temperature black arsenic phosphorus terahertz detector at room temperature with a chopping frequency of 1 kHz and an operating frequency of 0.12 THz;

Figure 4 shows the response waveforms of the adjustable room temperature black arsenic phosphorus terahertz detector at room temperature with a chopping frequency of 1 kHz and an operating frequency of 0.3 THz;

Figure 5 is a response diagram of a tunable room temperature black arsenic phosphorus terahertz detector under bias regulation;

Figure 6 is a response diagram of a tunable room temperature black arsenic phosphorus terahertz detector under gate voltage regulation.

Detailed ways:

The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings:

The invention provides a regulated room temperature black arsenic phosphorus terahertz detector and a preparation method, which realizes rapid and high-sensitivity room temperature terahertz detection. It works by generating a response signal through a highly localized and enhanced terahertz mixing electric field via an asymmetric high-efficiency terahertz antenna. The detector has the characteristics of high speed, wide frequency and high sensitivity, and can realize dual regulation of source-drain bias voltage and gate voltage, which provides a prototype device for large-scale application of room temperature terahertz detectors.

Specific steps are as follows:

1. Substrate selection

Intrinsic silicon and silicon dioxide overlying it are selected as substrates.

2. Black Arsenic Phosphorus Preparation and Transfer

Transfer black arsenic phosphorus to the substrate surface by mechanical lift-off transfer;

3. Using electron beam exposure technology, combined with electron beam deposition and traditional stripping process to prepare butterfly antenna, source and drain;

4. The dielectric layer is grown by atomic layer deposition, and its material is hafnium oxide;

5. The gate electrode is prepared on the dielectric layer by electron beam exposure and electron beam deposition technology, and the preparation of a tunable room temperature black arsenic phosphorus terahertz detector is completed.

7. The prepared black arsenic phosphorus terahertz detector was tested for photoelectric response. As shown in Figure 3, the terahertz source is a continuous wave system composed of a microwave source, a frequency multiplier, and an amplifier, and the frequency is between 0.02 and 0.3 terahertz. The detection device is irradiated with terahertz radiation, and the photocurrent signal generated by the detection device is amplified by the current amplifier (SR570) and input to the oscilloscope and the lock-in amplifier (SR830) respectively. The chopper signal built in the microwave source (E8257D) is used as the reference signal. Input to oscilloscope and lock-in amplifier respectively. During the test, the device exhibited ultra-high responsivity and fast detection capability.

a) When the thickness of black arsenic phosphorus is 20 nm, the channel length is 6 μm, and the power density of the THz source is 1 mW/mm2, a photocurrent of 12 nanoamps can be achieved.

b) When the black arsenic phosphorus thickness is 30 nm, the channel length is 6 μm, and the power density of the THz source is 1 mW per square millimeter, a photocurrent of 21 nanoamps can be achieved.

c) When the thickness of black arsenic phosphorus is 40 nm, the channel length is 6 μm, and the power density of the THz source is 1 mW/mm2, a photocurrent of 35 nanoamps can be achieved.

When the parameters of the detector structure in the present invention vary within a certain range, the room temperature black arsenic phosphorus terahertz detector has good detection performance. The test results show that the response time of the device can reach 1 microsecond, and the response rate at 0.12THz It can reach 100V/W, the noise equivalent power can reach 200pW/Hz ^0.5 , and the performance regulation under bias voltage and gate voltage can be realized, which can effectively detect terahertz waves at room temperature, and has a large number in the field of terahertz detection. application prospects.

Claims (2)

1. A tunable room temperature black arsenic phosphorus terahertz detector, comprising a substrate (1), black arsenic phosphorus (2), a butterfly antenna (3), a source electrode (4), a drain electrode (5), a medium Layer (6) and gate (7), characterized by: The structure of the detector from bottom to top is as follows: the first layer is a substrate (1), the second layer is black arsenic phosphorus (2), and a butterfly antenna (3) and an antenna mounted on the black arsenic phosphorus. The connected source electrode (4) and the drain electrode (5), the third layer is the dielectric layer (6), and the fourth layer is the gate electrode (7); The substrate (1) is intrinsic silicon with silicon dioxide; The black arsenic phosphorus (2) is multi-layer black arsenic phosphorus with a thickness of 20 nanometers to 40 nanometers; The butterfly antenna (3), the source electrode (4) and the drain electrode (5) all have two metal layers, the lower layer metal is titanium, and the upper layer metal is gold; The dielectric layer (6) is hafnium oxide; The gate (7) has two metal layers, the lower metal is titanium, and the upper metal is gold. 2. a method for preparing the adjustable room temperature black arsenic phosphorus terahertz detector as claimed in claim 1, is characterized in that comprising the following steps: 1) silicon dioxide is prepared on intrinsic silicon by thermal oxidation as a substrate (1); 2) preparing and transferring the black arsenic phosphorus (2) to the surface of the substrate (1) by a mechanical lift-off method; 3) The source electrode (4) and the drain electrode (5) of the butterfly antenna (3) are prepared by using electron beam exposure technology, combined with electron beam deposition and traditional lift-off process; 4) using the atomic layer deposition process to grow the dielectric layer (6); 5) A gate electrode (7) is prepared on the dielectric layer (6) by electron beam exposure and electron beam deposition technology, so as to complete the preparation of a tunable room temperature black arsenic phosphorus terahertz detector.

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