Graded Al Concentration III-V Semiconductor Structure
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Solution Overview
Problem
Semiconductor structures containing HEMT or MISFET devices face challenges in achieving low ON resistance and low device burnout rate, as high aluminum concentration in the donor-supply layer improves ON resistance but increases burnout rate, while lower concentrations reduce burnout but increase ON resistance, posing a tradeoff.
Innovation Solution
A semiconductor structure with a second III-V layer having a variable band gap, where the Al concentration is graded from lower near the channel layer to higher near the gate, allowing for a balance between ON resistance and burnout rate, achieved by forming a first III-V layer with a smaller band gap over a substrate and a second III-V layer with a wider band gap, including an Al-containing layer over a GaN layer with varying Al concentration profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high aluminum concentration is used in the donor-supply layer, then ON resistance is reduced, but crystal quality deteriorates
Solution Approach 1:
The graded Al concentration profile applies local quality by positioning lower aluminum concentrations (15-20%) at the channel interface where crystal quality is critical for device reliability, and higher concentrations (30-40%) toward the gate where ON resistance optimization is prioritized. This spatial differentiation allows the structure to simultaneously achieve low ON resistance and maintain high crystal quality in the critical channel region.
Solution Approach 2:
The donor-supply layer is effectively segmented into multiple regions with different aluminum concentrations. This segmentation creates distinct functional zones: a crystal-quality-critical region near the channel with lower Al content, and a resistance-optimization region toward the gate with higher Al content, allowing independent optimization of each zone's properties.
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 graded Al concentration in the second III-V layer effectively reduces dynamic on-resistance and device burnout rate, maintaining crystal quality and device performance by optimizing the Al concentration in the donor-supply layer.
Implementation Method 1
A semiconductor structure with a second III-V layer having a variable band gap, where the Al concentration is graded from lower near the channel layer to higher near the gate
Data Source
AI summary
The present disclosure provides a semiconductor structure, including a substrate, a first III-V layer over the substrate, having a first band gap, and a second III-V layer over the first III-V layer, having a second band gap. The second III-V layer includes a first surface in contact with the first III-V layer and a second surface opposite to the first surface. The second band gap at the second surface is greater than the second band gap at the first surface. The present disclosure also provides a manufacturing method of the aforesaid semiconductor structure.