Semiconductor Light-Emitting Element Current Distribution
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Solution Overview
Problem
Conventional semiconductor light-emitting elements experience concentration of electric current near the current supply part when high electric current is supplied, leading to increased temperature and reduced lifetime due to degradation, cracking, or melting of the n-type semiconductor layer.
Innovation Solution
A semiconductor light-emitting element structure is designed with a first current blocking layer having a higher contact resistance than the second electrode, preventing electric current concentration near the current supply part by directing it to flow horizontally, and a second current blocking layer with lower contact resistance than the first current blocking layer, facilitating even current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high electric current is supplied to increase light output, then light emission intensity is improved, but electric current concentrates near the current supply part causing temperature increase and element degradation
Solution Approach 1:
The patent applies local quality by creating different contact resistance characteristics in different regions of the electrode structure. Specifically, the inner peripheral portion of the lower electrode has a first contact resistance while the outer peripheral portion has a second contact resistance that is lower than the first. This localized differentiation of electrical properties directs current flow away from the high-current-density center region toward the periphery, preventing current concentration and thermal damage while maintaining high light output
2Reliability
If current blocking layer is added to prevent current concentration, then element lifetime is improved, but device complexity increases
Solution Approach 1:
The patent merges the current-blocking function into the existing lower electrode structure itself, rather than adding a separate current blocking layer. The lower electrode is designed with radially varying contact resistance (higher at inner periphery, lower at outer periphery), which inherently blocks current concentration without requiring additional structural components. This integration maintains simplicity while achieving the current distribution control needed for improved reliability
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 structure effectively prevents electric current concentration near the current supply part, reducing temperature increases and extending the element's lifespan even under high-power conditions, while also improving light extraction efficiency.
Implementation Method 1
The reflective electrode 103 reflects light emitted from the light-emitting layer 112 toward the support substrate 101 side (in a downward direction in the plane of paper) so that the light is guided to a light extraction surface provided on the n-side electrode 108 side.
Implementation Method 2
The bonding layer 102 is a conductive material that is provided to improve adhesion between the support substrate 101 and the reflective electrode 103 when they are bonded together.
Implementation Method 3
The ohmic contact layer 104 forms an ohmic contact with the semiconductor layer 107 at its interface with the semiconductor layer 107.
Data Source
AI summary
The semiconductor light-emitting element includes: a substrate; a semiconductor layer that is provided over the substrate; a first electrode that is provided in contact with part of an upper surface of the semiconductor layer and includes a current supply part; a second electrode that is provided in part of a region vertically below a region where the current supply part is not provided, that is in contact with part of the semiconductor layer; and a first current blocking layer that is provided in a region including a region vertically below the current supply part and that is in contact with part of the semiconductor layer, wherein a contact resistance at an interface between the first current blocking layer and the semiconductor layer is higher than that at an interface between the second electrode and the semiconductor layer.