Monolithic FET Antenna for Terahertz Detection
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Solution Overview
Problem
Existing terahertz wave detectors require large antennas due to the small channel area of field-effect transistors, leading to impedance mismatch and increased noise, as they struggle to efficiently convert terahertz waves into direct current output voltage without separate antenna structures.
Innovation Solution
A monolithic field-effect transistor-antenna device where the gate acts as an antenna, with the drain width determined by a first performance parameter for reception rate and the channel region width by a second parameter for detection, allowing for independent optimization and maximizing output voltage without additional noise-inducing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large-sized antenna is used to receive terahertz waves, then the terahertz wave reception rate is improved, but the impedance mismatch and noise increase due to size difference with the field-effect transistor
Solution Approach 1:
The patent merges the antenna and field-effect transistor into a single integrated device where the gate of the FET serves as the antenna. This eliminates the separate antenna structure and its associated impedance mismatch issues, while maintaining effective terahertz wave reception capability through the gate's direct coupling to the channel region.
Solution Approach 2:
The gate structure performs dual functions: it acts as both the antenna for receiving terahertz waves and as the control electrode for the field-effect transistor. This multi-functionality eliminates the need for a separate antenna component, resolving the impedance mismatch problem while maintaining reception efficiency.
2Measurement precision
If the channel area of the field-effect transistor is increased to improve detection sensitivity, then the detection sensitivity is improved, but the device area and impedance mismatch increase
Solution Approach 1:
The patent optimizes the local properties of the channel region by creating a surrounding structure that concentrates the electric field and charge distribution in the active detection area. This enhances detection sensitivity through improved charge asymmetry in the channel region without requiring a proportional increase in overall device area.
Solution Approach 2:
The channel region is configured in a surrounding structure that extends in multiple dimensions, allowing efficient charge distribution and detection sensitivity enhancement without linearly increasing the planar device area. The three-dimensional arrangement of the channel around the source region maximizes detection capability within a compact footprint.
3Productivity
If separate antenna structures are used for terahertz wave reception, then the reception capability is improved, but the device complexity and noise increase
Solution Approach 1:
The patent combines the antenna function and transistor control function into a single gate structure, eliminating the need for separate antenna components, additional connecting structures, and associated impedance matching circuits. This integration significantly reduces device complexity while maintaining full reception capability.
Solution Approach 2:
The gate structure serves multiple functions simultaneously: it acts as the terahertz wave antenna, the control electrode for the field-effect transistor, and the signal coupling element. This multi-functionality eliminates numerous separate components and simplifies the overall device architecture.
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 configuration enhances terahertz wave reception and detection sensitivity by integrating the antenna and transistor, reducing noise and power transfer losses, and enabling efficient conversion of terahertz waves to direct current output voltage.
Implementation Method 1
a gate among three connecting terminals—a source, a drain, and a gate—of the field-effect transistor may receive a terahertz (THz) wave which is an alternating current (AC) signal
Implementation Method 2
induce charge asymmetry into a lower semiconductor channel region between the source and the drain, and detect a terahertz wave signal based on a direct current (DC) voltage of the drain which is an output terminal by an asymmetrical charge distribution
Data Source
AI summary
A field-effect transistor for terahertz wave detection using a gate as an antenna includes a silicon substrate including a source and a drain formed outside a channel region surrounding the source, and a gate formed to be spaced apart from the silicon substrate and correspond to the channel region, on a dielectric layer formed on a surface of the silicon substrate, in which the drain has a width determined based on a first performance parameter associated with a terahertz wave reception rate of the field-effect transistor and the channel region has a width determined based on a second performance parameter associated with detection of a terahertz wave to be received by the field-effect transistor.