Nitride Semiconductor High Power Device With Multiple Quantum Well
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Solution Overview
Problem
In high power devices, a thick InGaN layer between GaN and AlGaN layers leads to lattice disconnection, causing lattice defects and reduced electron mobility and density in the 2DEG, resulting in decreased performance.
Innovation Solution
A high power device with a multiple quantum well layer structure, where InxGa1-xN and GaN layers are alternately stacked to form a channel layer, maintaining a thin InGaN layer within its critical film thickness to prevent relaxation and enhance crystallinity, and an AlGaN layer is formed to match lattice distances, creating a high-density 2DEG with improved electron mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the InGaN layer is thickly formed to increase electron density, then the electron density of 2DEG is improved, but the lattice connection between GaN and InGaN is cut off causing relaxation and lattice defects that decrease electron mobility
Solution Approach 1:
The InGaN layer is segmented into multiple thin layers (first InGaN layer and second InGaN layer) separated by a GaN layer. This segmentation allows each InGaN sub-layer to remain within its critical film thickness and avoid relaxation, while collectively providing sufficient thickness to maintain high electron density in the 2DEG at the interface with AlGaN.
Solution Approach 2:
The structure embeds a GaN layer within the InGaN layer stack, creating a nested configuration where the first InGaN layer contains the GaN layer which in turn contains the second InGaN layer. This nested structure maintains lattice connection throughout the stack while allowing sufficient total InGaN thickness for high electron density.
2Power
If the InGaN layer is thickly formed to enhance device performance, then the potential for high power operation is improved, but lattice defects are generated that reduce device reliability
Solution Approach 1:
The thick InGaN layer is divided into multiple thin InGaN layers separated by GaN, allowing the structure to achieve the total thickness needed for high power operation without any single layer exceeding its critical thickness and causing relaxation-induced defects.
Solution Approach 2:
The patent creates a composite nitride semiconductor structure combining InGaN and GaN layers in a specific configuration. This composite structure leverages the beneficial properties of both materials: InGaN for high electron density and GaN for lattice stability and defect suppression, achieving high power capability with improved reliability.
3Quantity of substance
If the InGaN layer is thickly formed to increase carrier concentration, then the electron density is improved, but crystal structure disturbance occurs that decreases electron mobility
Solution Approach 1:
The InGaN layer is divided into multiple thin sub-layers separated by GaN, ensuring each sub-layer remains within its critical film thickness and maintains stable crystal structure without relaxation, while collectively providing sufficient thickness for high electron density.
Solution Approach 2:
Different regions of the nitride semiconductor stack have different local compositions and thicknesses optimized for their specific functions: thin InGaN layers for maintaining crystal stability, GaN layers for lattice connection and structural stability, and the overall multi-layer configuration for achieving high electron density.
Data Source
AI summary
A high power device including with a first nitride semiconductor layer, a second nitride semiconductor layer formed on the first nitride semiconductor layer, and a third nitride semiconductor layer containing an Al element formed on the second nitride semiconductor layer. The second nitride semiconductor layer is a multiple quantum well layer in which a nitride semiconductor layer containing an In element and a nitride semiconductor layer not containing an In element are alternately stacked.