Composite Semiconductor Device for High Voltage and Low Forward Drop
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Solution Overview
Problem
Existing semiconductor diodes face challenges in achieving a balance between high voltage withstanding capability, low forward voltage drop, and short reverse recovery time, particularly in high-speed diode applications like inverters and switching-mode power supplies.
Innovation Solution
A composite semiconductor device is created by combining a semiconductor rectifier, such as a silicon pin-junction diode or Schottky barrier diode, with a unipolar field effect transistor, where the field effect transistor is designed to have a higher voltage withstanding capability than the rectifier, allowing for reduced forward voltage requirements and minimized current flow through the gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a silicon pin diode or fast recovery diode is used to achieve high voltage withstanding capability (up to 600 volts), then the antivoltage strength is improved, but the forward voltage drop increases and reverse recovery time is not zero
Solution Approach 1:
The patent combines a semiconductor rectifier (providing voltage withstanding capability) with a unipolar field effect transistor (providing low forward voltage drop) into a single integrated composite device. The rectifier and FET are merged such that the rectifier handles high voltage blocking while the FET handles low-voltage conduction, achieving both high antivoltage strength and low forward voltage drop simultaneously.
2Loss of energy
If a Schottky barrier diode is designed for low forward voltage drop, then the forward voltage requirement is reduced, but the voltage withstanding capability decreases due to increased current leakage
Solution Approach 1:
The patent segments the diode function into two separate components: the Schottky barrier diode handles the low forward voltage drop function, while the unipolar field effect transistor handles the high voltage withstanding function. This segmentation allows each component to be optimized for its specific function without compromising the other.
3Strength
If compound semiconductor diodes (GaN or SiC) are used to achieve high voltage withstanding capability (600 volts or more), then the antivoltage strength is improved, but the forward voltage drop increases
Solution Approach 1:
The patent creates a composite semiconductor device that integrates two different semiconductor materials: silicon (or other semiconductor) for the rectifier portion providing voltage withstanding capability, and the unipolar field effect transistor portion providing low forward voltage drop. This composite structure achieves the benefits of both materials without their individual limitations.
4Strength
If the field effect transistor is designed with high voltage withstanding capability between gate and drain, then the overall device antivoltage strength is improved, but the device complexity increases
Solution Approach 1:
The patent merges the semiconductor rectifier and unipolar field effect transistor into a single integrated composite device with shared electrodes and interconnected structures. The cathode of the rectifier connects to the source of the FET, and the gate of the FET connects to the anode of the rectifier, creating a unified device that appears simple externally while providing enhanced voltage withstanding capability internally.
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 results in a diode-like device with improved antivoltage strength, reduced forward voltage drop, and faster reverse recovery times, enhancing its performance in high-speed applications while maintaining a compact and efficient design.
Implementation Method 1
The Schottky barrier diode (SBD) is also known which has no reverse recovery time due to minority carrier storage
Implementation Method 2
The unipolar field effect transistor comprises a first main electrode coupled to the second electrode of the semiconductor rectifier, a second main electrode, and a gate electrode
Data Source
AI summary
A silicon-made low-forward-voltage Schottky barrier diode is serially combined with a high-antivoltage-strength high-electron-mobility transistor made from a nitride semiconductor that is wider in bandgap than silicon. The Schottky barrier diode has its anode connected to the gate, and its cathode to the source, of the HEMT. This HEMT is normally on. The reverse voltage withstanding capability of the complete device depends upon that between the drain and gate of the HEMT.