Group III-V Substrate Shaping for Crystallographic Orientation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The development of high-quality single crystalline Group III-V semiconductive materials, such as gallium nitride, is hindered by challenges in forming bulk GaN crystals with low defect density and crystalline morphological issues like bowing, which affect the performance and longevity of optoelectronic devices like LEDs and laser diodes.
Innovation Solution
A method involving the formation of a substrate with a Group III-V material, including gallium nitride, using a template substrate, buffer layers, and epitaxial growth processes, followed by shaping to modify physical and crystallographic bows, achieving an offcut angle variation of not greater than 0.6 degrees, thereby reducing dislocation density and improving crystalline orientation.
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 material can be obtained, but crystalline bowing and extended defects still occur
Solution Approach 1:
The patent applies preliminary action by performing a shaping process on the substrate before device fabrication. This pre-shaping step corrects crystalline bowing and reduces extended defects in advance, ensuring that subsequent device processing occurs on a substrate with optimized crystallographic orientation and reduced defects, thereby improving both crystalline quality and device reliability
Solution Approach 2:
The patent employs parameter changes by modifying the physical shape and crystallographic orientation parameters of the substrate through a controlled shaping process. By adjusting the substrate's bowing characteristics and offcut angles, the process optimizes crystalline quality and reduces defect density, directly addressing the contradiction between manufacturing precision and device reliability
2Ease of manufacture
If extended defects are present in the substrate, then manufacturing is easier, but device performance deteriorates significantly
Solution Approach 1:
The patent converts the harmful effect of extended defects into a benefit by using the shaping process to induce controlled stress and deformation that redistributes and reduces defect density. The shaping operation transforms the substrate's internal stress state in a way that eliminates threading dislocations and stacking faults, thereby improving device lifetime while maintaining manufacturing feasibility
3Manufacturing precision
If the substrate has high crystalline orientation precision, then device performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing the shaping process to achieve precise crystallographic orientation before device fabrication begins. This pre-establishment of orientation precision simplifies subsequent manufacturing steps, as devices can be processed on a substrate that already has the required crystallographic alignment, thereby reducing overall processing complexity while maintaining high orientation precision
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 reduced physical and crystalline bow, improved crystalline quality, and controlled offcut angles, enhancing the performance and reliability of optoelectronic devices by minimizing defects and maintaining consistent emission wavelengths across a wafer.
Implementation Method 1
the industry has turned to formation of bulk GaN crystals using epitaxial growth processes
Data Source
AI summary
A substrate including a body comprising a Group III-V material and having an upper surface, the body comprising an offcut angle defined between the upper surface and a crystallographic reference plane, and the body further having an offcut angle variation of not greater than about 0.6 degrees.