GaN Substrate Release Layer for Dislocation Reduction
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Solution Overview
Problem
The development of high-quality semiconductive substrates, particularly for LED and LD devices, is hindered by the formation of extended defects like threading dislocations, stacking faults, and antiphase boundaries in Group III-V materials such as gallium nitride, which reduce light-emitting efficiency and increase dark current, limiting the performance and lifetime of semiconductor devices.
Innovation Solution
A method involving a continuous growth process in a reaction chamber, where a release layer with a different dopant concentration than the base layer is formed between the base and epitaxial layers, allowing for the separation of semiconductive layers and reducing dislocation density through alterations in growth parameters such as temperature, rate, and reactant ratios, facilitating the formation of high-quality semiconductive substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial growth process is used to form bulk GaN crystals, then crystal formation is achieved, but extended defects like threading dislocations and stacking faults are formed
Solution Approach 1:
The patent divides the continuous growth process into distinct stages with different parameters. A first portion of the layer is grown under initial conditions, then a second portion is grown under modified conditions (changed V/III ratio, temperature, or pressure). This segmentation allows the early stage to establish crystal structure while the later stage reduces defect formation, resolving the contradiction between achieving crystal formation and minimizing dislocations.
Solution Approach 2:
The patent explicitly changes growth parameters during the epitaxial process. The V/III ratio, temperature, or pressure is modified between growing the first and second portions of the layer. This parameter change optimizes the growth conditions to reduce threading dislocation density and stacking faults while maintaining crystal formation, directly addressing the contradiction between reliability and manufacturing precision.
2Productivity
If continuous growth process is used to form multiple layers, then productivity is improved, but process control complexity increases
Solution Approach 1:
The patent maintains continuous growth throughout the process, never stopping the epitaxial reactor. The first and second portions of the layer are grown continuously under different parameters. This continuous operation maximizes productivity while the parameter changes are implemented smoothly during the ongoing process, balancing efficiency with controllable complexity.
Solution Approach 2:
The patent dynamically adjusts growth parameters during the continuous process. The V/III ratio, temperature, or pressure is changed mid-process to transition from growing the first portion to the second portion. This dynamic parameter adjustment enables continuous high-productivity growth while maintaining control over defect formation through timely parameter modifications.
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
This approach results in semiconductive substrates with reduced dislocation density and improved light-emitting efficiency, extending the operating lifetime of devices and enhancing the performance of semiconductor materials like gallium nitride.
Implementation Method 1
forming a release layer overlying the base layer during a continuous growth process
Data Source
AI summary
A method of forming a semiconductive substrate material for an electronic device including forming a plurality of semiconductive layers on a substrate during a continuous growth process in a reaction chamber, wherein during the continuous growth process, a release layer is formed between a base layer and an epitaxial layer by altering at least one growth process parameter during the continuous growth process. The method also including separating the plurality of semiconductive layers from the substrate.