阅读说明：本技术 石墨烯/三氧化二铝/砷化镓太赫兹探测器及其制作方法 (Graphene/aluminum oxide/gallium arsenide terahertz detector and manufacturing method thereof ) 是由 杨冬晓 王畅 林时胜 陆阳华 胡欣怡 于 2019-09-09 设计创作，主要内容包括：本发明公开了一种石墨烯/三氧化二铝/砷化镓太赫兹光电探测器及其制作方法。在N型砷化镓衬底上自下而上依次有三氧化二铝绝缘层、石墨烯层,并设有第一电极以及边电极；制备方法是先在N型掺杂的砷化镓片上制作边电极及三氧化二铝绝缘层,将石墨烯转移到三氧化二铝上,使得石墨烯/三氧化二铝/砷化镓接触形成隧穿异质结；再在石墨烯上制作第一电极,得到石墨烯/三氧化二铝/砷化镓光电探测器。本发明的太赫兹光电探测器通过异质结的隧穿效应进一步优化了其器件性能,暗态电流低,且对太赫兹波段具有极高的响应度与探测度,器件工艺简单。(The invention discloses a graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector and a manufacturing method thereof. An aluminum oxide insulating layer and a graphene layer are sequentially arranged on the N-type gallium arsenide substrate from bottom to top, and a first electrode and an edge electrode are arranged on the N-type gallium arsenide substrate; the preparation method comprises the steps of firstly manufacturing an edge electrode and an aluminum oxide insulating layer on an N-type doped gallium arsenide chip, and transferring graphene onto aluminum oxide to enable the graphene/the aluminum oxide/the gallium arsenide to be in contact with each other to form a tunneling heterojunction; and manufacturing a first electrode on the graphene to obtain the graphene/aluminum oxide/gallium arsenide photoelectric detector. The terahertz photoelectric detector further optimizes the device performance through the tunneling effect of the heterojunction, has low dark-state current, extremely high responsivity and detectivity to the terahertz waveband, and is simple in device process.)

1. A graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector comprises a substrate and is characterized in that the substrate is a gallium arsenide substrate (1), an aluminum oxide insulating layer (2) and a graphene layer (3) are sequentially arranged on the upper surface of the N-type gallium arsenide substrate (1) from bottom to top, and the gallium arsenide layer (1), the aluminum oxide insulating layer (2) and the graphene layer (3) are sequentially contacted to form a tunneling heterojunction; the graphene layer is characterized by further comprising a first electrode (4) and an edge electrode (5), wherein the first electrode (4) is arranged on the upper surface of the graphene layer (3), the first electrode (4) is of an annular structure, and the edge electrode (5) is arranged on the bottom surface of the gallium arsenide layer (1); the area of the aluminum oxide insulating layer (2) is larger than 10% of the area of the gallium arsenide substrate (1) and not larger than 100% of the area of the gallium arsenide layer (1), the area of the side electrode (4) accounts for 1% -10% of the area of the gallium arsenide substrate (1), the area of the first electrode (4) is smaller than the area of the graphene layer (3), and the area of the graphene layer (3) is not larger than the area of the gallium arsenide substrate (1).

2. The graphene/aluminum oxide/gallium arsenide terahertz photodetector of claim 1, wherein: the number of layers of the graphene layer (3) is 1 to 10, and P-type doping is adopted.

3. The graphene/aluminum oxide/gallium arsenide terahertz photodetector of claim 1, wherein: the aluminum oxide insulating layer (2) is made of aluminum oxide material with the thickness of 10-20 nm.

4. The graphene/aluminum oxide/gallium arsenide terahertz photodetector of claim 1, wherein: the first electrode (4) and the side electrode (5) are both selected from one or more composite electrodes of gold, silver and titanium, and the thickness is 1-500 nm.

5. The graphene/aluminum oxide/gallium arsenide terahertz photodetector of claim 1, wherein: the gallium arsenide substrate (1) is doped in an N type.

6. The method for preparing the graphene/aluminum oxide/gallium arsenide terahertz photodetector as claimed in any one of claims 1 to 5, wherein: the method comprises the following steps:

firstly, manufacturing a side electrode (5) on the bottom surface of an N-type doped gallium arsenide chip, wherein the area of the side electrode (5) accounts for 1-10% of the area of the gallium arsenide chip, then putting the gallium arsenide chip into a chemical cleaning solution to soak for 1-30 minutes for surface cleaning, cleaning the gallium arsenide chip by using deionized water, taking out the gallium arsenide chip and drying the gallium arsenide chip by blowing;

then growing aluminum oxide on the top surface of the gallium arsenide chip to form an aluminum oxide insulating layer (2), wherein the area of the aluminum oxide insulating layer (2) is larger than 10% of the area of the gallium arsenide chip but not larger than 100% of the area of the gallium arsenide chip, transferring the graphene chip layer to the top surface of the aluminum oxide insulating layer (2), and the area occupied by the graphene is not larger than the area of the gallium arsenide chip; and finally, manufacturing a first electrode (4) on the top surface of the graphene sheet layer to obtain the graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector.

7. The method for preparing the graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector according to claim 6, wherein the method comprises the following steps: and transferring the multilayer graphene sheet layer to the top surface of the aluminum oxide insulating layer (2).

Technical Field

The invention relates to a terahertz photoelectric detector and a preparation method thereof, in particular to a graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector and a preparation method thereof, and belongs to the technical field of photoelectric devices.

Background

In recent years, terahertz detectors have attracted extensive attention in research and industry as an important photoelectric device. The photodetector with the two-dimensional material/semiconductor heterojunction structure attracts more and more researchers due to extremely fast response, extremely high responsivity and detection performance, and can be widely applied to the fields of aviation and military.

Graphene materials were first discovered and prepared in 2004 and their research has progressed more rapidly after the Nobel prize was won in 2010. More researches show that the graphene material has excellent electrical, optical and mechanical properties, such as extremely high carrier mobility, extremely high light transmittance, high Young modulus, extremely high flexibility and the like. These excellent properties make graphene attract a wide range of attention and further have applications in the field of optoelectronic device technology, including photodetectors, solar cells, photosensors, and the like. In recent years, a great number of researchers have conducted application research of graphene in the direction of a photodetector, and the graphene has the advantages of being capable of achieving ultrafast response and having spectral response of a wide waveband, and being wide and convenient to apply as a two-dimensional material. But considering that graphene has a thickness of atomic size in the nanometer level, the light absorbed by graphene is relatively small (2.3%) in the visible light band, while the absorption rate in the terahertz band is relatively high and is related to terahertz frequency, temperature, graphene chemical potential and relaxation time. Therefore, the detection and enhancement of the absorption of terahertz light and the correspondence of the terahertz light are realized by finding a suitable material to combine with graphene or designing a new structure, and the method is the key point for researching and applying the graphene-based terahertz photoelectric detector.

Disclosure of Invention

In order to solve the problems in the background art, the invention aims to provide a graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector with extremely high responsivity and simple preparation process and a preparation method thereof. Research and experiments of the invention find that the light absorption rate can be effectively increased by combining the graphene and the semiconductor bulk material into a tunneling heterojunction structure by utilizing the tunneling effect, and extremely high responsivity and detection degree are obtained, so that the terahertz photoelectric detector and the preparation method thereof are designed.

The technical scheme adopted by the invention is as follows:

a graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector comprises:

the substrate is a gallium arsenide substrate, an aluminum oxide insulating layer and a graphene layer are sequentially arranged on the upper surface of the N-type gallium arsenide substrate from bottom to top, and the gallium arsenide layer, the aluminum oxide insulating layer and the graphene layer are sequentially contacted to form a tunneling heterojunction; the graphene layer is arranged on the upper surface of the graphene layer, the first electrode is of an annular structure, and the edge electrode is arranged on the bottom surface of the gallium arsenide layer; the area of the aluminum oxide insulating layer is larger than 10% of the area of the gallium arsenide substrate and not larger than 100% of the area of the gallium arsenide substrate, the area of the side electrode accounts for 1% -10% of the area of the gallium arsenide substrate, the area of the first electrode is smaller than the area of the graphene layer, and the area of the graphene layer is not larger than the area of the gallium arsenide substrate.

The tunneling heterojunction structure is arranged in the terahertz photoelectric detector, so that the terahertz photoelectric detection rate can be improved.

The number of layers of the graphene layers is 1 to 10, and P-type doping is adopted.

The aluminum oxide insulating layer is made of aluminum oxide material with the thickness of 10-20 nm.

The first electrode and the side electrode are both selected from one or more of gold, silver and titanium, and the thickness is 1-500 nm.

The gallium arsenide substrate is doped in an N type.

Secondly, a method for a graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector is characterized by comprising the following steps:

the N-type doped gallium arsenide chip is used as a gallium arsenide substrate, a side electrode with a certain area is manufactured on the bottom surface of the N-type doped gallium arsenide chip, the area of the side electrode accounts for 1% -10% of the area of the gallium arsenide chip, then the N-type doped gallium arsenide chip is placed into chemical cleaning liquid to be soaked for 1-30 minutes for surface cleaning, and the N-type doped gallium arsenide chip is taken out and dried by blowing after being cleaned by deionized water;

then growing aluminum oxide on the top surface of the gallium arsenide chip to form an aluminum oxide insulating layer, wherein the area of the aluminum oxide insulating layer is larger than 10% of that of the gallium arsenide chip but not larger than 100% of that of the gallium arsenide chip, transferring the graphene chip layer to the top surface of the aluminum oxide insulating layer, and the area occupied by the graphene is not larger than that of the gallium arsenide chip; and finally, manufacturing a first electrode on the top surface of the graphene sheet layer to obtain the graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector.

And transferring the multilayer graphene sheet layer to the top surface of the aluminum oxide insulating layer.

According to the invention, the graphene and the semiconductor material are combined, and if the Fermi levels of the graphene and the semiconductor material are greatly different, a Schottky junction can be formed. Under terahertz illumination, the graphene absorbs photon energy, internal electrons are subjected to in-band transition, and the electrons in the gallium arsenide are injected into the graphene under the action of a junction barrier electric field. The carrier concentration in the graphene changes along with the change of the carrier concentration, and the resistivity of the graphene also changes. The intensity of the external light changes, and the concentration of the injected electrons or holes also changes. The change of the resistance value of the graphene can reflect the detection response condition to the external illumination, and the current on two sides of the Schottky junction can be changed under the condition of no illumination under the condition of external voltage, so that the external illumination condition is reflected.

In addition, the Fermi level of the graphene can be adjusted through quantum dot light doping, the Schottky barrier is correspondingly changed, and the photoelectric detection performance of the device can be adjusted. The aluminum oxide layer embedded between the semiconductor and the graphene can be used as an insulating layer to inhibit the flow of current carriers between the semiconductor and the graphene so as to greatly reduce the current magnitude of the semiconductor in a dark state, and under the condition of illumination, the flow of the current carriers is greatly enhanced, the inhibiting effect can be ignored, and the magnitude of photocurrent cannot be influenced; on the other hand, a condition that a carrier generates a tunneling effect can be provided, so that a large number of carriers flow between the graphene and the gallium arsenide, and the responsivity of the detector is improved.

Compared with the prior art, the invention has the beneficial effects that:

compared with the traditional terahertz photoelectric detector, the graphene/aluminum oxide/gallium arsenide terahertz photoelectric detector has better light absorption and light detection response performance by utilizing the high carrier mobility, good photoelectric response and gallium arsenide excellent photoelectric property of the graphene and the heterojunction tunneling effect; and the preparation process is simple and easy to realize. Meanwhile, the interface characteristic of the aluminum oxide is utilized to reduce the dark current and provide the condition for generating tunneling, thereby obtaining extremely high responsivity and detection degree.

Drawings

Fig. 1 is a schematic structural diagram of a graphene/aluminum oxide/gallium arsenide terahertz photodetector;

fig. 2 is a schematic energy band diagram of a graphene/alumina/gallium arsenide heterojunction.

Fig. 3 is an I-V characteristic curve diagram of a graphene/aluminum oxide/gallium arsenide terahertz photodetector under the condition of presence or absence of terahertz illumination.

Fig. 4 is a graph of current change of the photodetector manufactured in the embodiment under different terahertz powers.

In the figure: the device comprises an N-type gallium arsenide substrate 1, an insulating layer 2, an aluminum oxide graphene layer 3, a first electrode 4 and an edge electrode 5.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

Referring to fig. 1, the graphene/aluminum oxide/gallium arsenide terahertz photodetector of the present invention is formed by sequentially providing an insulating layer 2, a graphene layer 3, a first electrode 4 and a side electrode 5 on the top surface of an N-type gallium arsenide substrate 1 from bottom to top, wherein the side electrode 5 is disposed on the bottom surface of the N-type doped gallium arsenide layer 1, and the first electrode 4 is disposed on the top surface of the graphene layer 3, such that a graphene/aluminum oxide/gallium arsenide heterojunction can be formed, and a schematic energy band structure diagram of the heterojunction is shown in fig. 2.

The method comprises the following steps that a Schottky junction is formed between graphene and gallium arsenide, under the condition of terahertz illumination, electrons in the graphene absorb energy to generate transition so as to change the density of current carriers of the graphene, under the action of an electric field of a junction barrier, electrons in the gallium arsenide tunnel into the graphene, and the Schottky barrier is correspondingly changed by adjusting the Fermi level of the graphene; the aluminum oxide layer is embedded between the gallium arsenide and the graphene and used as an insulating layer to inhibit the flow of carriers between the semiconductor and the graphene, so that the current magnitude of the semiconductor in a dark state can be greatly reduced.

The examples of the invention are as follows: