Group III Nitride Quantum Well Growth for Strain Relaxation
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Solution Overview
Problem
Group III nitride semiconductor devices face strain-related issues due to lattice mismatch between well and barrier layers, leading to deteriorated crystal quality and reduced light emission efficiency, with existing strain relaxation techniques being insufficient.
Innovation Solution
A method for producing Group III nitride semiconductor devices involves growing a first semiconductor layer and a second semiconductor layer with a larger band gap, using a variable composition layer with continuous In composition variation and an intermediate layer, and adjusting the hydrogen gas flow rate to relax strain and improve crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a well layer and barrier layer with different compositions are formed to create a quantum well structure, then light emission efficiency and response speed are improved, but strain is generated at the interface due to lattice mismatch, deteriorating crystal quality
Solution Approach 1:
An intermediate layer is introduced between the well layer and barrier layer to serve as a transition region. This intermediate layer has a composition that gradually changes from matching the well layer lattice constant to matching the barrier layer lattice constant, thereby mediating the lattice mismatch and reducing strain at the interface while preserving the quantum well structure's light emission efficiency
Solution Approach 2:
The composition of the intermediate layer is continuously varied along the growth direction to create a gradient structure. By changing the lattice constant parameter gradually from the well layer value to the barrier layer value, the strain is distributed and relaxed, preventing defect formation while maintaining the functional properties of the quantum well
2Manufacturing precision
If the lattice mismatch between well layer and barrier layer is reduced to prevent misfit dislocation, then crystal quality is improved, but the quantum well effect is weakened, reducing light emission efficiency
Solution Approach 1:
The barrier layer is segmented into multiple regions: the main barrier layer with high Al composition for strong confinement, and an intermediate layer with graded composition for strain relaxation. This segmentation allows the system to simultaneously achieve good crystal quality in the main barrier and effective quantum well effect in the well layer
Solution Approach 2:
Different regions of the barrier layer are assigned different compositions tailored to their specific functions. The intermediate layer near the well layer has a composition optimized for strain relaxation, while the main barrier layer has a composition optimized for carrier confinement, achieving local optimization that benefits the overall device performance
3Manufacturing precision
If strain is relaxed by forming a gradient composition layer, then crystal quality is improved, but the device complexity increases due to additional layers and composition control
Solution Approach 1:
Instead of creating a complete gradient across the entire barrier layer, the composition gradient is applied only partially in the intermediate layer adjacent to the well layer. This partial application of the gradient strategy achieves sufficient strain relaxation without requiring complex composition control throughout the entire structure, thereby limiting the increase in device complexity
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 approach effectively relaxes strain between semiconductor layers, enhancing crystal quality and light emission efficiency by reducing piezoelectric fields and improving sub-band formation.
Implementation Method 1
a variable composition layer in which an In composition is varied continuously in a streamline shape in the direction perpendicular to a surface in contact with the first semiconductor layer
Implementation Method 2
growing a first semiconductor layer and growing a second semiconductor layer
Data Source
AI summary
The present invention provides a method for producing a Group III nitride semiconductor device which can relax strain between a Group III nitride semiconductor layer containing In and a semiconductor layer adjacent thereto, and a production method therefor. The well layer is a Group III nitride semiconductor layer containing In. The barrier layer is a Group III nitride semiconductor layer. The well layer and the barrier layer are brought into contact with each other in at least one of growing a well layer and growing a barrier layer. A gas containing hydrogen gas as a carrier gas is used in growing a well layer and growing a barrier layer. In growing a barrier layer, the flow rate of hydrogen gas is higher than the flow rate of hydrogen gas in growing a well layer.