Monolithic HEMT-Schottky Layout for Uninterrupted Reverse Current
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Solution Overview
Problem
Field-effect semiconductor devices, such as HEMT and MESFET, face challenges when connected to inductive or capacitive loads, leading to reverse voltage issues and require complex and costly circuitry for normal-off operation, and integrating a discrete diode increases size and cost.
Innovation Solution
A monolithic integrated circuit combining a field-effect semiconductor device with a Schottky diode, where the Schottky electrode is positioned away from the source across the gate, ensuring current flow without depletion region interruption, and a carrier storage layer is used to achieve normally-off operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discrete diode is connected in parallel with the field-effect semiconductor device for feedback and protection, then the device reliability is improved, but the device size and manufacturing cost increase
Solution Approach 1:
The patent merges the diode function with the field-effect semiconductor device by forming a Schottky diode within the same semiconductor structure. The Schottky electrode is formed on the semiconductor layer to create a Schottky diode, while the gate electrode controls the field-effect device. This integration eliminates the need for a separate discrete diode, reducing device size while maintaining feedback and protection functions.
2Reliability
If a discrete diode is connected in parallel with the field-effect semiconductor device for feedback and protection, then the device reliability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent combines the diode and field-effect device fabrication into a single monolithic process. Both the Schottky diode (via Schottky electrode) and the field-effect device (via gate electrode) are formed on the same semiconductor layer using integrated manufacturing steps, eliminating the need for separate discrete component assembly and reducing manufacturing cost.
3Ease of manufacture
If the Schottky electrode is positioned on the source side of the gate, then the diode can be integrated, but the current flow is interrupted by the depletion region when the device is off
Solution Approach 1:
The patent positions the Schottky electrode on the drain side of the gate electrode, changing the spatial arrangement from source-side to drain-side. This dimensional repositioning ensures that the Schottky diode current path does not intersect with the gate's depletion region, allowing continuous current flow when the device is off while maintaining integration.
4Ease of operation
If a negative power supply is used to turn off the HEMT, then the device can operate normally off, but the circuitry becomes complex and expensive
Solution Approach 1:
The patent modifies the semiconductor layer to create an asymmetric structure with different doping concentrations in the source and drain regions. This parameter change creates an inherent potential barrier that prevents current flow in the off state without requiring negative gate voltage, enabling normally-off operation through structural parameters rather than complex circuitry.
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
The solution allows for compact, cost-effective integration of a diode within the semiconductor device, ensuring reliable feedback and protection without size increase and enabling normally-off operation without negative power supply complexity.
Implementation Method 1
a Schottky electrode which is formed on the main semiconductor region in Schottky contact therewith in order to provide a Schottky diode
Implementation Method 2
The two-dimensional electron gas layer of the field-effect semiconductor device will then be interrupted by the depletion region spreading from the gate when the device is off
Implementation Method 3
The piezoelectric and spontaneous depolarization of the heterojunction surfaces creates the familiar two-dimensional electron gas layer as the channel between drain and source
Implementation Method 4
The piezoelectric and spontaneous depolarization of the heterojunction surfaces creates the familiar two-dimensional electron gas layer as the channel between drain and source
Data Source
AI summary
A field-effect semiconductor device such as a HEMT or MESFET is monolithically integrated with a Schottky diode for feedback, regeneration, or protection purposes. The field-effect semiconductor device includes a main semiconductor region having formed thereon a source, a drain, and a gate between the source and the drain. Also formed on the main semiconductor region, preferably between gate and drain, is a Schottky electrode electrically coupled to the source. The Schottky electrode provides a Schottky diode in combination with the main semiconductor region. A current flow is assured from Schottky electrode to drain without interruption by a depletion region expanding from the gate.