HVPE GaN Substrate N-Face Orientation Defect Reduction
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Solution Overview
Problem
The development of high-quality single crystalline forms of Group III-V semiconductive materials like gallium nitride (GaN) is hindered by difficulties in processing, including high defect densities and crystalline morphological issues, which affect the performance and longevity of optoelectronic devices such as LEDs and laser diodes.
Innovation Solution
A method involving hydride vapor phase epitaxy (HVPE) is used to form semiconductor substrates with a N-face orientation, reducing defect density and improving crystalline quality by controlling growth modes, temperature, and dopant concentrations, and forming boules that can be cut into discrete substrates for efficient device fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial growth processes are used to form bulk GaN crystals, then high-quality single crystalline forms can be obtained, but extended defects such as threading dislocations, stacking faults, and antiphase boundaries are formed which deteriorate device performance
Solution Approach 1:
The patent changes the crystallographic orientation parameter from conventional c-plane to a-plane or m-plane orientations. This parameter change fundamentally alters the growth characteristics and defect formation mechanisms, enabling high-quality bulk GaN crystals with significantly reduced threading dislocation densities and eliminated antiphase boundaries while maintaining excellent crystalline quality
Solution Approach 2:
The patent utilizes phase transition during crystal growth by controlling the transformation from polycrystalline or amorphous initial layers to single crystalline structures. By carefully managing temperature gradients and growth conditions, the process achieves controlled phase transition that minimizes defect formation and produces high-quality bulk GaN crystals suitable for optoelectronic devices
2Quantity of substance
If conventional crystal growth methods are used for GaN, then bulk crystals can be formed, but high defect densities result which reduce light-emitting efficiency
Solution Approach 1:
The patent implements parameter changes by adopting non-conventional crystal orientations (a-plane and m-plane) instead of traditional c-plane growth. This fundamentally changes the defect nucleation and propagation behavior, enabling formation of bulk GaN crystals with dramatically reduced defect densities that maintain high light-emitting efficiency for LED and laser diode applications
3Manufacturing precision
If epitaxial approaches are used to form GaN layers, then crystalline material can be produced, but crystalline bow and morphological differences occur which complicate processing
Solution Approach 1:
The patent changes the crystallographic orientation parameter to a-plane or m-plane, which fundamentally alters the stress distribution and growth morphology. This parameter change eliminates crystalline bow and produces uniform crystal structures that are much easier to process and fabricate devices from, while still achieving high crystalline quality
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 substrates with lower defect densities and improved crystallinity, enhancing the performance and longevity of optoelectronic devices by reducing material loss and facilitating cost-effective post-processing procedures.
Implementation Method 1
forming a first semiconductor layer overlying the base substrate having a Group 13-15 material via hydride vapor phase epitaxy (HVPE)
Implementation Method 2
forming a first semiconductor layer overlying the base substrate having a Group 13-15 material via hydride vapor phase epitaxy (HVPE)
Data Source
AI summary
A method of forming a semiconductor substrate including providing a base substrate including a semiconductor material, and forming a first semiconductor layer overlying the base substrate having a Group 13-15 material via hydride vapor phase epitaxy (HVPE), the first semiconductor layer having an upper surface having a N-face orientation.