GaN Light Emitting Element With Convex Reflector
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Solution Overview
Problem
Existing surface-emitting laser elements, particularly those using nitride semiconductors, face challenges in achieving uniformity in the length of the resonator and experiencing increased contact resistance between the second conductivity type layer and the electrode, due to variations in the removal process of the substrate during manufacturing.
Innovation Solution
The method involves forming a first light reflecting layer with a convex shape or a convexity on the substrate, which acts as a stopper during substrate removal, and etching the first surface of the compound semiconductor layer to form a first electrode, thereby suppressing removal variations and contact resistance. This process includes forming a layered structure with GaN-based compound semiconductors, fixing the second light reflecting layer to a support substrate, and removing the substrate to expose the first surface and forming the first electrode on the etched surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate is removed by CMP method to expose the second conductivity type layer, then the light scattering is suppressed, but the removal amount varies causing non-uniform resonator length
Solution Approach 1:
A convexity is formed on the substrate before removing the substrate. This convexity serves as a stopper that prevents the substrate removal process from completely exposing the second conductivity type layer, thereby maintaining a controlled interface between the substrate and the semiconductor layer. This preliminary structural preparation ensures uniform resonator length while preventing excessive substrate removal that would increase contact resistance.
2Object-affected harmful factors
If the second conductivity type layer is completely exposed by removing the substrate, then light scattering is minimized, but the contact resistance between the layer and electrode increases
Solution Approach 1:
The convexity structure is preliminarily formed to counteract the complete exposure of the second conductivity type layer. By providing this protruding structure, the patent prevents the substrate from being removed to the point where contact resistance increases, while still allowing sufficient substrate removal to minimize light scattering. The convexity acts as a protective element that anticipates and prevents the harmful effect of excessive substrate removal.
3Illumination intensity
If mirror finishing is performed on the exposed surface to suppress light scattering, then optical performance improves, but the contact resistance between the layer and electrode rises
Solution Approach 1:
The convexity is formed preliminarily on the substrate before mirror finishing is performed. This preliminary structural preparation ensures that when mirror finishing is applied to suppress light scattering, the convexity remains as a protective element preventing complete exposure of the second conductivity type layer. Thus, optical performance is improved through mirror finishing while the convexity prevents the associated increase in contact resistance.
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 ensures uniformity in the resonator length and stability in the light emitting element characteristics by minimizing substrate removal variations and reducing contact resistance between the semiconductor layer and the electrode.
Implementation Method 1
forming a first light reflecting layer with a convex shape or a convexity on the substrate, which acts as a stopper during substrate removal
Implementation Method 2
etching the first surface of the compound semiconductor layer to form a first electrode
Data Source
AI summary
A method of manufacturing a light emitting element includes, sequentially (a) forming a first light reflecting layer having a convex shape; (b) forming a layered structure body by layering a first compound semiconductor layer, an active layer, and a second compound semiconductor layer; (c) forming, on the second surface of the second compound semiconductor layer, a second electrode and a second light reflecting layer formed from a multilayer film; (d) fixing the second light reflecting layer to a support substrate; (e) removing the substrate for manufacturing a light emitting element, and exposing the first surface of the first compound semiconductor layer and the first light reflecting layer; (f) etching the first surface of the first compound semiconductor layer; and (g) forming a first electrode on at least the etched first surface of the first compound semiconductor layer.