CN112002999B

CN112002999B - Simple manufacturing method of THz antenna

Info

Publication number: CN112002999B
Application number: CN202010769198.5A
Authority: CN
Inventors: 吴蕊; 赵亚平; 苏波
Original assignee: Capital Normal University
Current assignee: Capital Normal University
Priority date: 2020-08-03
Filing date: 2020-08-03
Publication date: 2023-05-23
Anticipated expiration: 2040-08-03
Also published as: CN112002999A

Abstract

The invention discloses a simple manufacturing method of a THz antenna, which comprises the steps of fixing a copper wire with the diameter of 200 mu m at the middle position of an LT-GaAs epitaxial wafer, plating a gold layer on the epitaxial wafer by an evaporation method, taking down the copper wire after gold plating is finished, forming two electrodes, and then performing subsequent welding work; the method reasonably uses a copper wire with the diameter of 200 mu m to assist in evaporating metallic gold, forms a THz antenna gap with a small aperture by a simple method, directly adopts a low-temperature gallium arsenide (LT-GaAs) epitaxial wafer, omits the step of film corrosion during the traditional THz antenna manufacturing, effectively avoids the problems of certain toxicity of corrosive solution, unsound bonding between a surface photoconductive material and a substrate and the like, and has the advantages of high signal intensity, good integrity, high sample recycling rate, small heating value, long-term use, safe material and no harm to experimental personnel; the manufactured antenna can obtain complete THz signals and can be repeatedly used for a plurality of times.

Description

Simple manufacturing method of THz antenna

Technical Field

The invention belongs to the technical field of THz antennas, and particularly relates to a simple manufacturing method of a THz antenna.

Background

The traditional THz film antenna is required to be subjected to the steps of corrosion of a photoconductive material LT-GaAs, mask design of an electrode structure, photoetching, post-treatment and the like, wherein the solution has certain toxicity during the corrosion of the LT-GaAs, the operation is unsafe, and the success rate is low. The photoetching step is also divided into gold plating, spin coating photoresist, pre-baking, exposure, development, post-baking, plasma etching, alcohol washing and the like, and has longer period and more complex manufacture. And the antenna has the heating problem, or the breakdown of the film is easy to be caused when the laser power is large, and the finished product reuse rate is not high. For example, "Terahertz vibrational absorption spectroscopy using microstrip-line waveguides" paper published in journal Applied Physics Letters, 2008 (volume 93, 18), used a method of etching away AlAs sacrificial layers to obtain a 350nm LT-GaAs film, and transferring it to a new substrate as a photoconductive antenna. The sacrificial layer is corroded by using 10% hydrofluoric acid solution, so that the sacrificial layer has certain toxicity, the method is complex, the period is long, and the film is easy to break or is not tightly bonded with the substrate. The effect of antenna geometry on LT-GaAs (LT-GaAs) photoconductive THz emission [ J ] semiconductor technology, 2008 (S1): 52-54.) existing techniques (Cui Lijie, zeng Yiping, wang Baojiang, etc.) all require masking, uv lithography, and subsequent lift-off processes to produce antenna structures to achieve antenna gaps on the order of μm.

Disclosure of Invention

Therefore, the invention aims to provide a simple manufacturing method of the THz antenna, which is safe and simple in preparation process and high in reuse rate of the manufactured THz photoconductive antenna.

A manufacturing method of a THz antenna comprises the following steps:

step 1, cleaning a low-temperature GaAs epitaxial wafer;

step 2, fixing the low-temperature GaAs epitaxial wafer on an evaporation substrate;

step 3, fixing a copper wire with the diameter of 200 mu m on the epitaxial wafer along the central line of the width direction or the length direction of the epitaxial wafer, wherein the length of the copper wire penetrates through the length or the width of the low-temperature GaAs epitaxial wafer;

step 4, putting the low-temperature GaAs epitaxial wafer into a vacuum evaporator, evaporating a chromium layer with the thickness of 20nm on the surface of the fixed copper wire, and evaporating a gold layer with the thickness of 200 nm;

and 5, taking out the low-temperature GaAs epitaxial wafer, taking down the copper wire on the low-temperature GaAs epitaxial wafer, and forming two electrodes by the evaporated gold layer to obtain the THz antenna.

Further, the method also comprises the following steps:

step 6, welding two electrodes on the PCB; placing the low-temperature GaAs epitaxial wafer on a PCB, enabling two electrodes on the low-temperature GaAs epitaxial wafer to be respectively overlapped with two electrodes on the PCB, and connecting the electrodes by using conductive silver adhesive;

and 7, finally, welding wires at the joint of the two electrodes of the PCB for externally connecting other devices.

Preferably, the preparation method of the low-temperature GaAs epitaxial wafer comprises the following steps:

based on the semi-insulating GaAs layer, a buffer GaAs layer is grown at 580 ℃, and then a photoconductive material layer is grown at 200 ℃ to obtain the low-temperature GaAs layer.

Preferably, in the step 1, the low-temperature GaAs epitaxial wafer is cleaned with alcohol.

Preferably, in the step 2, a special adhesive tape for evaporation is used to fix the low-temperature GaAs epitaxial wafer on the evaporation substrate.

The invention has the following beneficial effects:

according to the simple manufacturing method of the THz antenna, a copper wire with the diameter of 200 mu m is fixed in the middle of an LT-GaAs epitaxial wafer, a gold layer is plated on the epitaxial wafer by an evaporation method, the copper wire is taken down after gold plating is finished, two electrodes can be formed, and then subsequent welding work is carried out; the method reasonably uses a copper wire with the diameter of 200 mu m to assist in evaporating metallic gold, forms a THz antenna gap with a small aperture by a simple method, directly adopts a low-temperature gallium arsenide (LT-GaAs) epitaxial wafer, omits the step of film corrosion during the traditional THz antenna manufacturing, effectively avoids the problems of certain toxicity of corrosive solution, unsound bonding between a surface photoconductive material and a substrate and the like, and has the advantages of high signal intensity, good integrity, high sample recycling rate, small heating value, long-term use, safe material and no harm to experimental personnel; the manufactured antenna can obtain complete THz signals and can be repeatedly used for a plurality of times.

Drawings

Fig. 1 is a schematic view of a THz antenna LT-GaAs epitaxial wafer substrate.

FIG. 2 is a schematic diagram of a process for forming an electrode gap using a 200 μm diameter copper wire.

Fig. 3 is a THz antenna performance test optical path.

Fig. 4 is a schematic diagram of THz antenna radiation signals;

fig. 5 is a graph of THz time domain signals obtained using the antenna of the present invention.

Detailed Description

The invention will now be described in detail by way of example with reference to the accompanying drawings.

A manufacturing method of THz antenna comprises the following basic implementation processes:

1. firstly, cleaning an LT-GaAs epitaxial wafer in alcohol;

2. then fixing the epitaxial wafer on the evaporation substrate by using a special adhesive tape for evaporation;

3. and then fixing a copper wire with the diameter of 200 mu m on the epitaxial wafer along the central line of the width direction or the length direction of the epitaxial wafer, wherein the length of the copper wire penetrates through the whole central line, so that the finally evaporated gold layer is divided into two parts, and short circuit is avoided.

4. The metal electrode is evaporated in a vacuum evaporator, firstly, the chromium with the thickness of 20nm is evaporated (used for fixing gold), and then the gold with the thickness of 200nm is evaporated.

5. After taking out the evaporation substrate, carefully taking down the epitaxial wafer by using tweezers, then taking down the copper wires, forming an electrode gap, and forming two electrodes by the evaporated gold layer, thereby forming the THz antenna.

6. Because the THz antenna is small in size and is inconvenient to weld wires, the two electrodes are welded on the PCB, the epitaxial wafer is placed on the PCB, the two electrodes on the epitaxial wafer are respectively overlapped with the PCB, and then the electrodes are connected by using conductive silver adhesive.

7. And finally, welding a lead at the joint of the PCB for externally connecting a power supply or a lock-in amplifier.

Thus, the entire fabrication process of the THz antenna is realized.

The preparation process is as follows:

firstly, preparing an LT-GaAs epitaxial wafer, growing buffer layer gallium arsenide (GaAs) at 580 ℃ based on a semi-insulating gallium arsenide (SI-GaAs) layer, and then growing a photoconductive material layer at 200 ℃ to obtain LT-GaAs with the thickness of 2 mu m, as shown in figure 1. And (3) using the extension piece as a substrate, and continuing to carry out a gold plating step, wherein a copper wire with the diameter of 200 mu m is used for assisting in forming an antenna electrode during gold plating. As shown in fig. 2, the vacuum evaporator is vertical, so that the copper wire is not plated with metal, and the evaporated metal is 20nm chromium and 200nm gold. And taking out the sample, removing the copper wire, forming an antenna electrode with 200 mu m, connecting the electrode evaporated on the epitaxial wafer with a PCB (printed circuit board) by using conductive silver paste, and leading out a wire from the PCB to be connected with a power supply or a lock-in amplifier for use as a THz generating or detecting antenna. Fig. 3 is a graph of an antenna test light path based on 800nm laser, and the laser irradiates THz waves after entering an antenna gap, as shown in fig. 4, and is collected by a detection antenna after being focused by an off-axis parabolic mirror. Fig. 5 shows the detected THz time domain signal, which proves that the THz antenna manufactured by the method can obtain a signal with high and stable strength, and the sample can be used for multiple times, so that the durability is strong. The antenna is simple in manufacturing method and small in size, and can be manufactured in batches or combined with other structures.

In summary, the above embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The manufacturing method of the THz antenna is characterized by comprising the following steps of:

step 1, cleaning a low-temperature GaAs epitaxial wafer;

step 4, placing the low-temperature GaAs epitaxial wafer into a vacuum evaporator for vertical evaporation, firstly evaporating a chromium layer with the thickness of 20nm on the surface of the low-temperature epitaxial wafer with the copper wire fixed, and then evaporating a gold layer with the thickness of 200 nm;

2. The method of manufacturing a THz antenna of claim 1, further comprising the steps of:

3. The method for manufacturing the THz antenna according to claim 1, wherein the method for manufacturing the low-temperature GaAs epitaxial wafer comprises the following steps:

4. The method for manufacturing a THz antenna according to claim 1, wherein in the step 1, the low-temperature GaAs epitaxial wafer is cleaned with alcohol.

5. The method for manufacturing a THz antenna according to claim 1, wherein in the step 2, the low-temperature GaAs epitaxial wafer is fixed on the evaporation substrate using a tape dedicated for evaporation.