Nitride Semiconductor Layer Dislocation Management
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Solution Overview
Problem
Current semiconductor light emitting devices using nitride semiconductors face challenges in increasing external quantum efficiency due to dislocations and pit density, which affect the luminous efficiency and surface flatness.
Innovation Solution
A semiconductor light emitting device is designed with a foundation layer having unevenness on its surface, where dislocations are managed by forming a first layer with a lower group V to group III source material ratio and a second layer with a higher ratio, allowing dislocations to intersect and be annihilated, resulting in reduced dislocation density and improved surface flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a nitride semiconductor layer is grown to increase external quantum efficiency, then luminous efficiency is improved, but dislocation density increases and surface flatness deteriorates
Solution Approach 1:
The nitride semiconductor layer is divided into multiple layers with different group V to group III source material ratios. The first layer has a lower ratio while the second layer has a higher ratio, creating distinct zones that manage dislocation propagation differently to maintain both efficiency and surface quality
Solution Approach 2:
The group V to group III source material ratio is changed between layers to control dislocation behavior. By adjusting this chemical parameter, the patent achieves dislocation annihilation in the second layer while maintaining the benefits of nitride semiconductor light emission
2Manufacturing precision
If dislocation density is reduced to improve surface flatness, then manufacturing precision is improved, but external quantum efficiency may be compromised
Solution Approach 1:
Different regions of the nitride semiconductor structure have different source material ratios optimized for their specific functions. The first layer's lower ratio addresses surface flatness while the second layer's higher ratio maintains light emission efficiency, with the transition zone enabling dislocation management
Solution Approach 2:
The patent converts the harmful effect of dislocations into a beneficial process by using controlled dislocation propagation through the first layer that terminates in the second layer. This transforms dislocation-induced surface degradation into a mechanism for dislocation annihilation that actually improves overall device quality
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 approach leads to a nitride semiconductor light emitting device with enhanced efficiency and high surface flatness, achieving a balance between low dislocation density and high luminous efficiency.
Implementation Method 1
allowing dislocations to intersect and be annihilated, resulting in reduced dislocation density and improved surface flatness
Data Source
AI summary
According to an embodiment, a semiconductor light emitting device includes a foundation layer, a first semiconductor layer, a light emitting layer, and a second semiconductor layer. The foundation layer has an unevenness having recesses, side portions, and protrusions. A first major surface of the foundation layer has an overlay-region. The foundation layer has a plurality of dislocations including first dislocations whose one ends reaching the recess and second dislocations whose one ends reaching the protrusion. A proportion of a number of the second dislocations reaching the first major surface to a number of all of the second dislocations is smaller than a proportion of a number of the first dislocations reaching the first major surface to a number of all of the first dislocations. A number of the dislocations reaching the overlay-region of the first major surface is smaller than a number of all of the first dislocations.