Multi-Periodic Patterned Substrate for Faster Nitride Coalescence
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Solution Overview
Problem
Current group III nitride semiconductor devices face challenges in achieving high-quality active layers due to the limitations of bulk native substrates, with patterned sapphire substrates requiring longer coalescence times and affecting crystal quality.
Innovation Solution
A multi-periodic patterned substrate design is introduced, featuring closely spaced structures within larger spacings, allowing for improved lateral growth and faster coalescence, reducing dislocations and enhancing crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wider spacing is used in the patterned substrate, then crystal quality of group III nitride layers is improved, but coalescence time increases
Solution Approach 1:
The substrate surface is segmented into multiple periodic patterns with different spacing characteristics. The first periodic pattern provides closely spaced structures for rapid initial coalescence, while the second periodic pattern provides larger spacing for improved crystal quality. This segmentation allows the system to achieve both fast coalescence and high crystal quality simultaneously by having different regions serve different functions during the growth process.
2Productivity
If closely spaced structures are used in the patterned substrate, then coalescence time is reduced, but crystal quality deteriorates
Solution Approach 1:
Different regions of the substrate surface are assigned different local qualities through the multi-periodic pattern. Areas with the first periodic pattern (closer spacing) promote rapid coalescence and higher productivity, while areas with the second periodic pattern (larger spacing) promote superior crystal quality. This local differentiation allows each region to optimize for its specific function, and the overall system benefits from both fast coalescence and high crystal quality in different locations.
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 multi-periodic patterned substrate facilitates higher-quality semiconductor layer growth by balancing lateral and vertical growth, reducing dislocations and improving light transmission, resulting in enhanced optoelectronic device performance.
Implementation Method 1
The PSS causes the group III nitride crystal to nucleate in a defined pattern before growing laterally to coalesce into a planar film
Data Source
AI summary
A substrate includes structures formed on a growth surface of the substrate. The structures are formed in a multi-periodic pattern, which includes a first plurality of groups of structures. Each group of structures has a characteristic spacing between adjacent structures in the group. Each group of structures is separated from an adjacent group of structures by a second characteristic spacing. The second characteristic spacing is at least 1.5 times larger than the first characteristic spacing.