GaN Growth on Grooved Sapphire Substrates for Non-Polar Surfaces
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Solution Overview
Problem
Conventional methods for producing Group III nitride semiconductor products with non-polar or semi-polar surfaces face challenges in achieving high reproducibility, large substrate size, and uniform crystallinity, often resulting in poor device performance due to piezoelectric fields and in-plane variation in crystallinity.
Innovation Solution
A method involving the formation of grooves on a growth substrate, followed by epitaxial growth of the Group III nitride semiconductor on the groove side surfaces in a direction parallel to the substrate's main surface, using a buffer film and controlled temperature to enhance crystallinity and surface flatness, while avoiding growth on the substrate's flat surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a GaN layer is grown on a growth substrate using conventional methods, then the substrate size is limited by the thickness of the GaN layer, but increasing the substrate size is needed for mass production and large-area applications
Solution Approach 1:
The invention segments the growth substrate surface by forming grooves that divide the surface into multiple regions. These grooves create isolated growth zones where GaN layers can be grown independently, allowing each zone to maintain uniform crystallinity while the overall substrate area is significantly increased for mass production applications
Solution Approach 2:
The invention applies local quality by creating distinct regions on the substrate through groove formation. Each groove region provides a localized environment with controlled crystal orientation, ensuring that the GaN layer grown in each region maintains high crystallinity and uniformity, while the overall substrate can be large-scale
2Shape
If an m-plane or a-plane GaN substrate is produced by cutting out a grown GaN layer, then non-polar or semi-polar surfaces are obtained, but in-plane variation in crystallinity occurs due to poor crystallinity near the substrate interface
Solution Approach 1:
The invention extracts or removes the problematic region near the substrate interface by forming grooves that isolate the growth zones. This allows the GaN layer to be grown only in the groove regions where crystallinity can be maintained uniformly, effectively removing the influence of the poor-quality interface region on the final product
Solution Approach 2:
The invention performs preliminary action by forming grooves and applying masks before GaN layer growth. This preliminary structuring of the substrate ensures that only regions with proper crystal orientation receive the GaN layer, preventing in-plane variation in crystallinity from the outset
3Object-affected harmful factors
If conventional crystal growth techniques are used on non-polar or semi-polar substrates, then piezoelectric fields are avoided, but high reproducibility in forming the semiconductor product is difficult to achieve
Solution Approach 1:
The invention implements feedback control by using masks that precisely control where GaN layers grow on the substrate. The mask pattern provides feedback guidance for the epitaxial growth process, ensuring that layers are deposited only in regions with correct crystal orientation, thereby achieving high reproducibility while maintaining piezoelectric field elimination
Solution Approach 2:
The invention changes critical growth parameters by controlling the crystal orientation of the substrate surface through groove formation and mask application. By adjusting the orientation parameters and growth conditions in specific regions, the method achieves reproducible production of high-quality non-polar or semi-polar GaN products
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 allows for the high-reproducibility production of Group III nitride semiconductor products with non-polar or semi-polar surfaces, improving crystallinity and surface flatness, and enabling large-area production without the detrimental effects of piezoelectric fields.
Implementation Method 1
epitaxially growing the Group III nitride semiconductor on side surfaces of the groove at the growth temperature
Data Source
AI summary
A semiconductor substrate includes a sapphire substrate including a c-plane main surface and a groove in a surface thereof, the groove including side surfaces and a bottom surface, and a Group III nitride semiconductor layer formed on the sapphire substrate. The side surfaces of the groove are an a-plane of sapphire. An axis of the Group III nitride semiconductor layer, perpendicular to one of the side surface of the groove, is a c-axis of Group III nitride semiconductor. A plane of the Group III nitride semiconductor, parallel to the main surface of the sapphire substrate, is an a-plane of Group III nitride semiconductor.