CN111400848A - Antenna Design Method for Terahertz Wave Detector Based on Field Effect Transistor - Google Patents

Abstract

The invention discloses an antenna design method of a terahertz wave detector based on a field effect transistor, which comprises the following steps: constructing a terahertz wave detector model; setting a beam of planar terahertz waves with variable frequencies, and vertically irradiating the planar terahertz waves onto a terahertz wave detector model of the integrated antenna; extracting the electric field intensity of a position in a channel of a field effect transistor of the terahertz wave detector model; calculating the electric field enhancement generated by the antenna at different frequencies to obtain the variation relation of the electric field enhancement along with the frequency; acquiring the center frequency of the antenna according to the calculated change relation; and determining the structure and the size of the antenna according to the central frequency of the antenna. The terahertz antenna design method does not need to extract input impedance between the grid source electrodes of the field effect transistor, can be visually associated with the responsivity of the terahertz wave detector, and is visual and effective.

Description

Antenna Design Method for Terahertz Wave Detector Based on Field Effect Transistor

technical field

The invention relates to the design field of a plane integrated antenna, in particular to an antenna design method of a terahertz wave detector based on a field effect transistor.

Background technique

Terahertz waves are electromagnetic waves with a frequency of 0.1THz-10THz, between infrared and millimeter waves, and occupy an important position in the electromagnetic spectrum. Terahertz waves are widely used in material characterization, high-resolution imaging, medical diagnosis, security inspection, information communication, radar detection, atmospheric and Environmental detection and many other fields have extremely important applications. Therefore, in recent years, the terahertz band has attracted more and more attention and research. Terahertz wave detectors based on field effect transistors began with the plasma wave theory proposed by Dyakonov and Shur in 1993, and then actual devices were developed on different materials. Due to its small size, easy integration with chips, fast response speed, and room temperature operation, this terahertz wave detector has become a mainstream terahertz wave detection method.

Usually, in order to further improve the responsivity of the detector, the terahertz wave detector based on the field effect transistor couples the terahertz wave in space by connecting the source and the gate with a planar antenna, thereby generating a terahertz wave between the gate and source electrodes. The AC signal, which modulates the plasma wave in the transistor channel, ultimately produces a DC terahertz response signal between the transistor drain and source. Obviously, a reasonable antenna design can enhance the coupling efficiency between terahertz waves and transistors, thereby further improving the responsivity of detection. Based on the reciprocity of the antenna, the characteristic parameters of the antenna in the receive mode are the same as those in the transmit mode. Therefore, most of the traditional antenna designs are also based on the electromagnetic simulation of the antenna in the transmitting mode, and the performance of the antenna is measured by S-parameters, radiation efficiency, gain, etc. This kind of simulation must involve the matching of the antenna source impedance and the antenna impedance. For field effect transistor terahertz wave detectors, the input impedance between the gate-source electrodes of the transistor can be regarded as the source impedance in the antenna simulation. However, due to the lack of simple and accurate input impedance extraction methods for field effect transistors in the terahertz band, the traditional antenna design methods must lack sufficient effectiveness.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

In view of the above technical problems, the present invention proposes an antenna design method for a terahertz wave detector based on field effect transistors to at least partially solve the above technical problems.

(2) Technical solutions

According to an aspect of the present invention, an antenna design method for a terahertz wave detector based on a field effect transistor is provided, including:

Build a terahertz wave detector model;

A beam of planar terahertz waves with varying frequencies is set to be vertically incident on the terahertz wave detector model of the integrated antenna;

extracting the electric field intensity at a position in the channel of the field effect transistor of the terahertz wave detector model;

Calculate the electric field enhancement generated by the antenna at different frequencies, and obtain the variation relationship of the electric field enhancement with frequency;

Obtain the center frequency of the antenna according to the calculated variation relationship;

The structure and size of the antenna are determined according to the center frequency of the antenna.

In a further embodiment, the location where the electric field strength is extracted is located in the channel on the side edge of the gate of the field effect transistor close to the source.

In a further embodiment, the constructed terahertz wave detector model includes: a field effect transistor and a planar antenna; wherein the planar antenna is connected to the gate and source of the field effect transistor, respectively.

In further embodiments, the field effect transistor comprises:

substrate;

a buffer layer, placed on the substrate;

a channel layer, placed on the buffer layer;

a gate dielectric layer, placed on the channel layer;

A gate electrode, a drain electrode and a source electrode are placed on the gate dielectric layer, wherein the gate electrode is placed between the drain electrode and the source electrode.

In a further embodiment, the extraction of the electric field strength at a position of the field effect transistor is: by selecting the ComplexMag_E function in the Fields Calculator in HFSS, the electric field strength at the position is calculated.

In a further embodiment, the calculation of the electric field enhancement at different frequencies is: dividing the extracted electric field strength by the electric field strength of the incident terahertz wave to obtain the electric field enhancement of the antenna at this position.

In a further embodiment, the center frequency of the antenna is a frequency corresponding to a peak in the electric field enhancement as a function of frequency.

In further embodiments, the field effect transistor is a MOSFET, FINFET, MESFET or HEMT.

In further embodiments, the antenna is a butterfly antenna, a dipole antenna or a patch antenna.

In a further embodiment, the determining the structure and size of the antenna according to the center frequency of the antenna includes:

According to whether the center frequency of the antenna is consistent with the target frequency, adjust the size of the antenna so that the center frequency is consistent with the target frequency;

The antenna structure with relatively large electric field enhancement is selected according to the electric field enhancement at the center frequency of the antennas of different structures.

(3) Beneficial effects

The invention provides an antenna design method for a terahertz wave detector based on a field effect transistor, which utilizes the electric field enhancement of the antenna in the channel below the gate edge of the field effect transistor to characterize the performance of the antenna, so as to carry out effective field effect transistor terahertz wave detection. The design of the detector; the method does not need to extract the input impedance between the gate-source electrodes of the field effect transistor, and can be directly related to the responsivity of the terahertz wave detector. It is an intuitive and effective method for designing a terahertz antenna.

Description of drawings

FIG. 1 is a top view of the structure of a terahertz wave detector with an integrated antenna constructed in an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the field effect transistor part of the terahertz wave detector of the integrated antenna according to the embodiment of the present invention.

FIG. 3 is a flowchart of an antenna design method for a field effect transistor-based terahertz wave detector according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

According to an embodiment of the present invention, an antenna design method for a field effect transistor-based terahertz wave detector is provided, as shown in FIG. 3 , including:

Build a terahertz wave detector model;

A beam of planar terahertz waves with varying frequencies is set to be vertically incident on the terahertz wave detector model of the integrated antenna;

extracting the electric field intensity at a position in the channel of the field effect transistor of the terahertz wave detector model;

Calculate the electric field enhancement generated by the antenna at different frequencies, and obtain the variation relationship of the electric field enhancement with frequency;

Obtain the center frequency of the antenna according to the calculated variation relationship;

The structure and size of the antenna are determined according to the center frequency of the antenna.

Wherein, in the step of selecting a suitable structure and size, the center frequency of the antenna can be obtained according to the calculated variation relationship, and then the size of the antenna can be adjusted according to the target frequency, and the electric field enhancement in the channel of the antenna with different structure types can be compared. The relative size of the terahertz wave detector can be used to select the appropriate structure and size in the design of the terahertz wave detector antenna.

The determining the structure and size of the antenna according to the center frequency of the antenna includes: adjusting the size of the antenna to make the center frequency consistent with the target frequency according to whether the center frequency of the antenna is consistent with the target frequency; The electric field enhancement of the antenna at the center frequency selects an antenna structure with a relatively large electric field enhancement.

In this embodiment, the frequency position corresponding to the peak in the relationship between the electric field enhancement and frequency represents the center frequency of the antenna; the relative magnitude of the electric field enhancement peak represents the receiving performance of different antennas, that is, the coupled terahertz waves are converted into terahertz waves The ability to respond, which is directly related to the magnitude of the terahertz responsivity.

The invention utilizes the electric field enhancement of the antenna in the channel below the gate edge of the field effect transistor to characterize the performance of the terahertz antenna, and can be correlated with the responsivity of the terahertz wave detector. Specifically, terahertz wave detectors based on field effect transistors generally couple the terahertz waves in space by externally connecting planar antennas to the source and gate, so as to modulate the plasma wave in the channel of the field effect transistor, and finally A DC terahertz response signal is generated between the drain and source of the field effect transistor. The present invention utilizes the electric field enhancement of the antenna in the channel below the gate edge of the field effect transistor to characterize this modulation effect of the antenna, so as to carry out effective terahertz antenna design.

The antenna design method of the present invention has nothing to do with the specific antenna structure and size; has nothing to do with the specific operating frequency of the antenna (covering all electromagnetic wave bands); has nothing to do with the structure of the field effect transistor detector specifically used; The antenna has nothing to do with how the FET is connected.

In this embodiment, the constructed terahertz wave detector refers to all forms of field effect transistor detectors, including but not limited to MOSFET, FINFET, MESFET, HEMT and so on.

In this embodiment, the antenna types refer to all types of planar antennas, including but not limited to: butterfly antennas, dipole antennas, patch antennas, and the like.

In this embodiment, the constructed terahertz wave detector model includes: a field effect transistor and a planar antenna; wherein the planar antenna is connected to the gate and source of the field effect transistor, respectively.

In this embodiment, the field effect transistor as shown in FIG. 2 includes:

substrate 10;

The buffer layer 9 is placed on the substrate 10;

The channel layer 8 is placed on the buffer layer 9;

The gate dielectric layer 7 is placed on the channel layer 8;

Wherein, as shown in FIG. 1 , the gate electrode 1 , the drain electrode 2 and the source electrode 5 are placed on the gate dielectric layer 7 , wherein the gate electrode 1 is placed between the drain electrode 2 and the source electrode 5 . between.

In this embodiment, the simulation and calculation method used in the constructed terahertz wave detector model may be any form of simulation and calculation method, including but not limited to: MATLAB, HFSS, COMSEL and other simulation software (or FEM, FDTD, etc. and simulation algorithms such as MOM).

In this embodiment, the extraction of the electric field strength in the channel below the edge of the FET gate close to the source is: by selecting the ComplexMag_E function in the Fields Calculator in HFSS, selecting the FET gate close to the source a A specific location of the channel below the side edge extracts the electric field strength there.

In this embodiment, the calculation of the electric field enhancement at different frequency points is as follows: dividing the extracted electric field strength by the electric field strength of the incident terahertz wave to obtain the electric field enhancement of the antenna at that position.

Aiming at the special principle of terahertz wave detectors based on field effect transistors, the main function of the AC signal coupled between the gate-source electrodes is to modulate the plasma wave in the channel of the field effect transistor, and the electric field generated by the antenna in the channel must play a role. plays a very important role. Therefore, the present invention proposes a method to characterize the performance of the antenna by using the electric field enhancement of the antenna in the channel below the gate edge of the field effect transistor, so as to carry out the design of an effective field effect transistor terahertz wave detector.

It should be noted that demonstrations of parameters including specific values may be provided herein, but these parameters need not be exactly equal to the corresponding values, but may be approximated within acceptable error tolerances or design constraints. The directional terms mentioned in the embodiments, such as "up", "down", "front", "rear", "left", "right", etc., are only for referring to the directions of the drawings, and are not intended to limit the present invention. protected range. Furthermore, unless the steps are specifically described or must occur sequentially, the order of the above steps is not limited to those listed above, and may be varied or rearranged according to the desired design. And the above embodiments can be mixed and matched with each other or with other embodiments based on the consideration of design and reliability, that is, the technical features in different embodiments can be freely combined to form more embodiments.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned specific embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principle of the present invention, any modifications, equivalent replacements, improvements, etc. made should be included within the protection scope of the present invention.

Claims (10)

1. A design method of an antenna of a terahertz wave detector based on a field effect transistor is characterized by comprising the following steps:

constructing a terahertz wave detector model;

setting a beam of planar terahertz waves with variable frequencies, and vertically irradiating the planar terahertz waves onto a terahertz wave detector model of the integrated antenna;

extracting the electric field intensity of a position in a channel of a field effect transistor of the terahertz wave detector model;

calculating the electric field enhancement generated by the antenna at different frequencies to obtain the variation relation of the electric field enhancement along with the frequency;

acquiring the center frequency of the antenna according to the calculated change relation;

and determining the structure and the size of the antenna according to the center frequency of the antenna.

2. The antenna design method for a terahertz-wave detector based on a field-effect transistor according to claim 1, wherein the position for extracting the electric field intensity is located in a channel of a gate of the field-effect transistor near an edge of one side of a source.

3. The antenna design method for a terahertz wave detector based on a field effect transistor according to claim 1, wherein the constructed terahertz wave detector model comprises: a field effect transistor and a planar antenna; the planar antenna is respectively connected with the grid electrode and the source electrode of the field effect transistor.

4. The antenna design method for a terahertz-wave detector based on a field-effect transistor according to claim 3, wherein the field-effect transistor includes:

a substrate (10);

a buffer layer (9) disposed on the substrate (10);

a channel layer (8) disposed on the buffer layer (9);

a gate dielectric layer (7) disposed on the channel layer (8);

the grid electrode (1), the drain electrode (2) and the source electrode (5) are arranged on the grid dielectric layer (7), wherein the grid electrode (1) is arranged between the drain electrode (2) and the source electrode (5).

5. The antenna design method for a thz wave detector based on a field effect transistor according to claim 1, wherein the electric field strength at a position of the field effect transistor is extracted as follows: the electric field strength at the location is calculated by selecting the ComplexMag _ E function inside the Fields Calculator in HFSS.

6. The antenna design method for a thz wave detector based on a field effect transistor according to claim 1, wherein the calculating of the electric field enhancement at different frequencies is: and dividing the extracted electric field intensity by the electric field intensity of the incident terahertz wave to obtain the electric field enhancement of the antenna at the position.

7. The antenna design method for a thz wave probe based on a field effect transistor according to claim 1, wherein the center frequency of the antenna is a frequency corresponding to a peak in the variation of the electric field enhancement with frequency.

8. The antenna design method for a terahertz wave detector based on a field effect transistor according to claim 1, wherein the field effect transistor is a MOSFET, a FINFET, a MESFET or a HEMT.

9. The antenna design method for a terahertz wave detector based on a field effect transistor according to claim 1, wherein the antenna is a bowtie antenna, a dipole antenna or a patch antenna.

10. The antenna design method for a field-effect-transistor-based terahertz-wave detector according to any one of claims 1-9, wherein the determining the structure and the size of the antenna according to the center frequency of the antenna comprises:

adjusting the size of the antenna to enable the center frequency of the antenna to be consistent with the target frequency according to whether the center frequency of the antenna is consistent with the target frequency;

antenna configurations with relatively large electric field enhancement are selected based on the electric field enhancement at the center frequency of the differently configured antennas.

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