GaN Schottky Diode Aperture Design for Low On-Resistance
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Solution Overview
Problem
Conventional Schottky diodes using Si-based materials face limitations in on-state resistance, leakage current, forward voltage drop, and material defect sensitivity, with high fabrication costs.
Innovation Solution
A GaN-based Schottky diode design featuring a heterojunction between AlGaN and GaN layers with a dielectric layer and strategically formed openings or trenches, allowing the anode to contact the two-dimensional electron gas conduction channel through limited projections, reducing the metal-semiconductor contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional Si-based Schottky diodes are used, then high breakdown voltage is achieved, but on-resistance is high and switching loss is high
Solution Approach 1:
The patent changes the material parameter from conventional Si-based semiconductors to GaN-based wide bandgap semiconductor materials. This fundamental material parameter change enables simultaneously achieving high breakdown voltage and low on-resistance, thereby reducing switching loss while maintaining the high voltage blocking capability
Solution Approach 2:
The patent employs composite semiconductor structure with AlGaN barrier layer and GaN drift layer. This composite material approach leverages the high bandgap of AlGaN for high breakdown voltage and the high electron mobility of GaN for low on-resistance, resolving the contradiction between voltage blocking and conduction performance
2Reliability
If metal anode contact is formed directly on semiconductor layer, then low contact resistance is achieved, but leakage current increases
Solution Approach 1:
The patent applies local quality by forming dielectric layer with openings only in specific regions where anode contact is needed. The metal anode contacts the 2DEG conduction channel through these localized openings, maintaining low contact resistance at contact points while the dielectric material in surrounding areas blocks leakage current paths
Solution Approach 2:
The dielectric layer acts as an intermediary between the metal anode and the semiconductor layer. It provides electrical isolation in most areas to prevent leakage while allowing controlled contact through openings, thus mediating between the need for low contact resistance and the need to minimize leakage current
3Loss of energy
If heterojunction structure with 2DEG is formed, then low on-resistance is achieved, but fabrication complexity increases
Solution Approach 1:
The patent employs preliminary action by forming the AlGaN/GaN heterojunction structure with 2DEG conduction channel during the semiconductor layer fabrication process itself, before adding the dielectric layer and metal contacts. This preliminary formation of the low-resistance conduction path simplifies subsequent fabrication steps while achieving low on-resistance
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 design achieves reduced on-state resistance, lower leakage current, lower forward voltage drop, and lower fabrication costs, while being less sensitive to material defects.
Implementation Method 1
a heterojunction formed by two semiconductor materials disposed between an anode and a cathode of said diode, the heterojunction forming a two-dimensional electron gas conduction channel
Implementation Method 2
adding a layer of a dielectric material between a heterojunction formed by two semiconductor materials disposed between an anode and a cathode of said diode
Data Source
Figure 1~3a
Figure 4a~4b
Figure 5a~6
AI summary
A diode and a method of making same has a cathode an anode and one or more semiconductor layers disposed between the cathode and the anode. A dielectric layer is disposed between at least one of the one or more semiconductor layers and at least one of the cathode or anode, the dielectric layer having one or more openings or trenches formed therein through which the at least one of said cathode or anode projects into the at least one of the one or more semiconductor layers, wherein a ratio of a total surface area of the one or more openings or trenches formed in the dielectric layer at the at least one of the one or more semiconductor layers to a total surface area of the dielectric layer at the at least one of the one or more semiconductor layers is no greater than 0.25.