Nitride Semiconductor Element with Oriented Projections
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Solution Overview
Problem
Nitride semiconductor elements formed on sapphire substrates face challenges in reducing dislocation density, which affects their temperature characteristics and light emission efficiency.
Innovation Solution
A nitride semiconductor element is manufactured using a sapphire substrate with elongated projections, where the outer edge of these projections is oriented at an angle between -10° to +10° with respect to the a-plane of the substrate, facilitating reduced dislocation density and improved temperature characteristics by allowing lateral growth of the nitride semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elongated trenches (recess portions) are provided at the sapphire substrate to reduce dislocation density, then dislocation density is reduced, but crystallinity deteriorates when crystal growth timing differs between the trench bottom and upper surface
Solution Approach 1:
Instead of providing recess portions (trenches) at the sapphire substrate to reduce dislocation density, the invention inverts the approach by providing elongated projections (convex portions) at the sapphire substrate. This inversion maintains the dislocation reduction effect while avoiding the crystallinity deterioration problem that occurs with recess portions when crystal growth timing differs between different surfaces.
2Reliability
If the outer edge of projections is oriented at an angle of -10° to +10° with respect to the a-plane, then lateral growth of nitride semiconductor layer is facilitated and dislocations converge, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a particular parameter range for the projection outer edge orientation angle (-10° to +10° with respect to the a-plane) that optimizes lateral growth of the nitride semiconductor layer and convergence of dislocations. This parameter change facilitates improved temperature characteristics while maintaining feasible manufacturing precision through the defined angular range.
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 method results in a nitride semiconductor element with a low dislocation density, enhancing its temperature characteristics and light emission efficiency by converging dislocations and reducing electron trapping.
Implementation Method 1
growing a nitride semiconductor layer on the surface of the sapphire substrate with the projections formed thereat
Data Source
AI summary
A nitride semiconductor element includes a sapphire substrate including: a main surface extending in a c-plane of the sapphire substrate, and a plurality of projections disposed at the main surface, the plurality of projections including at least one projection having an elongated shape in a plan view; and a nitride semiconductor layer disposed on the main surface of the sapphire substrate. The at least one projection has an outer edge extending in a longitudinal direction of the elongated shape, the outer edge extending in a direction oriented at an angle in a range of −10° to +10° with respect to an a-plane of the sapphire substrate in the plan view.