AlGaN Back-Barrier Structure for GaN Current Collapse Suppression
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Solution Overview
Problem
Semiconductor power devices using GaN materials suffer from current collapse due to electron trapping in defect regions, leading to increased turn-on resistance and reduced efficiency during switching operations.
Innovation Solution
The semiconductor power device incorporates a back-barrier structure with a second back-barrier layer and a high resistance interlayer, both doped with carbon or iron, to block electron trapping and reduce current leakage, thereby minimizing current collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional AlGaN/GaN structure is used, then the device can operate at high frequency and high power, but electron trapping in defect regions causes current collapse and increased turn-on resistance
Solution Approach 1:
The barrier structure is segmented into multiple functional layers: a first barrier layer (Alx1Ga1-x1N with x1≥0.5) adjacent to the channel layer, a second barrier layer (Alx2Ga1-x2N with x2<0.5) adjacent to the buffer structure, and an interlayer between them. This segmentation creates distinct functional zones that prevent electron trapping while maintaining high power operation capability.
Solution Approach 2:
Different regions of the barrier structure are assigned different aluminum composition ratios to optimize local functions. The first barrier layer has high aluminum content (x1≥0.5) to provide strong electron blocking at the channel interface, while the second barrier layer has lower aluminum content (x2<0.5) to reduce lattice mismatch with the buffer structure, and the interlayer composition is optimized for interface quality.
2Reliability
If the aluminum composition ratio in the barrier layer is increased to improve electron blocking, then turn-on resistance stability improves, but lattice mismatch and dislocation density increase
Solution Approach 1:
The barrier structure is divided into two segments with different aluminum compositions. The first barrier layer uses high aluminum content (x1≥0.5) for effective electron blocking, while the second barrier layer uses lower aluminum content (x2<0.5) to minimize lattice mismatch with the AlGaN buffer structure, thereby reducing dislocation density while maintaining turn-on resistance stability.
Solution Approach 2:
The interlayer acts as an intermediary between the first and second barrier layers, providing a transition zone that accommodates the composition gradient. This intermediate structure helps manage lattice mismatch progressively, reducing the generation of dislocations while enabling the high aluminum content needed for effective electron blocking in the first barrier layer.
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 effectively reduces current collapse, maintaining device performance by preventing electron trapping and ensuring consistent drain-to-source current, as evidenced by a turn-on resistance ratio closer to one before and after off-state stressing.
Implementation Method 1
a first back-barrier layer on the first functional layer... a material of the first back-barrier layer includes Alx1Ga1-x1N... 0.5≤x1≤1
Implementation Method 2
an interlayer between the first back-barrier layer and the first functional layer... a material of the interlayer includes Alx3Ga1-x3N... x2<x3≤x1
Implementation Method 3
both doped with carbon or iron, to block electron trapping and reduce current leakage
Implementation Method 4
both doped with carbon or iron, to block electron trapping and reduce current leakage
Data Source
AI summary
A semiconductor power device includes a substrate; a buffer structure formed on the substrate; a barrier structure formed on the buffer structure; a channel layer formed on the barrier structure; and a barrier layer formed on the channel layer; wherein the barrier structure includes a first functional layer on the buffer structure, a second functional layer formed between the first functional layer and the buffer structure, a first back-barrier layer on the first functional layer, and an interlayer between the first back-barrier layer and the first functional layer; wherein a material of the first back-barrier layer includes Alx1Ga1-x1N, a material of the first functional layer includes Alx2Ga1-x2N, a material of the interlayer includes Alx3Ga1-x3N, a material of the second functional layer includes Alx4Ga1-x4N, wherein 0<x1≤1, 0≤x2≤1, 0≤x3≤1, 0≤x4<1, and x1≠x2; and wherein the first functional layer includes a first thickness, the second functional layer includes a second thickness, and the second thickness is greater than the first thickness.