Ring-Type FET Terahertz Detection Using Metal Gate Antenna
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Solution Overview
Problem
Existing silicon-based field-effect transistors (FETs) face challenges in achieving high sensitivity for terahertz wave detection due to symmetric structures, which are prone to noise, and require complex processes to create asymmetric source/drain areas, limiting the integration of peripheral elements like antennas and amplifiers.
Innovation Solution
A ring-type FET design using a silicon base with a metal gate as an antenna, where the source and channel are circular and ring-shaped respectively, allowing for adjustable overlap areas to enhance asymmetry and sensitivity without additional antenna structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetric structure is used in silicon FET-based detectors, then the manufacturing process is simple, but the sensitivity is limited due to noise susceptibility
Solution Approach 1:
The patent applies asymmetry by designing the gate electrode to overlap only with the source region or only with the drain region, creating an asymmetric charge distribution in the channel. This asymmetric structure enhances the photoresponse sensitivity to terahertz waves while maintaining compatibility with standard silicon fabrication processes, thereby resolving the contradiction between manufacturing simplicity and detection sensitivity.
2Measurement precision
If additional complex mask processes are used to create asymmetric source/drain areas, then the detection sensitivity improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the antenna function with the gate electrode, eliminating the need for separate antenna structures and their associated fabrication processes. The gate electrode serves dual purposes: as the control electrode for the FET and as the antenna for receiving terahertz waves. This integration maintains detection sensitivity while significantly reducing device complexity and manufacturing steps.
Solution Approach 2:
The gate electrode is designed to perform multiple functions simultaneously: it acts as the control gate for the field-effect transistor, serves as the antenna for terahertz wave reception, and creates the asymmetric charge distribution necessary for sensitive detection. This multi-functionality eliminates the need for additional specialized components and processes.
3Measurement precision
If compound semiconductors are used to form 2D channel charge, then the charge formation efficiency is high, but the manufacturing cost and integration difficulty increase
Solution Approach 1:
The patent changes the material parameter from compound semiconductors to silicon, achieving comparable charge formation efficiency through optimized device geometry and electric field distribution. The asymmetric gate overlap structure enhances the field effect in silicon, allowing efficient 2D channel charge formation without requiring expensive compound semiconductor materials, thereby reducing manufacturing cost and improving integrability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves high sensitivity and integration of peripheral elements at lower costs, enabling effective terahertz wave detection with reduced noise and complex process requirements.
Implementation Method 1
a ring-type FET for detecting a terahertz wave using a gate metal as an antenna
Implementation Method 2
a charge of a channel may be gathered in a two-dimensional (2D) form by a gate field effect
Implementation Method 3
the FET-based THz detector may detect a photoresponse using a direct current (DC) voltage of an output terminal, for example, the drain D, thereby detecting a signal
Data Source
AI summary
A ring-type FET may include a silicon base, a source formed on a portion of the silicon base through doping, a channel formed to encompass the source on a plane, a drain formed outside the channel, a dielectric layer formed on the source, the channel and the drain, and a gate provided on the dielectric layer, wherein a center of the source is spaced apart from a center of the channel, and the gate is formed of a metal material, disposed above the channel and configured to cover an upper face of the channel and overlap a portion of the source and a portion of the drain.