Surface-Emitting LED Electrode Layout for Uniform Current Injection
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Solution Overview
Problem
Existing surface-emitting semiconductor light-emitting devices face challenges in achieving uniform electron injection and maintaining high luminous efficiency due to non-uniform current distribution in the active layer, particularly when the semiconductor substrate is thinned, leading to reduced light output and disturbed far field patterns.
Innovation Solution
Incorporating rotationally asymmetric fine wire contact portions in the second electrode, which extend into the surface-emitting region of the semiconductor substrate, to uniformly distribute electron injection and minimize disturbances in the far field pattern while maintaining light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the semiconductor substrate thickness is increased to improve mechanical strength, then the structural stability is improved, but the current distribution uniformity deteriorates leading to reduced light output characteristics
Solution Approach 1:
A current distribution control layer is introduced as an intermediary between the semiconductor substrate and the active layer. This layer has a different resistivity than the substrate, acting as a mediator to redistribute the current flow and improve uniformity across the junction, thereby resolving the contradiction between mechanical strength and current distribution uniformity.
Solution Approach 2:
The resistivity parameter of the control layer is specifically optimized to be different from the substrate resistivity. By changing this electrical parameter, the current distribution is improved without altering the mechanical substrate thickness, thus maintaining strength while achieving uniform current flow.
2Device complexity
If conventional electrode structures are used, then the device structure is simple, but non-uniform electron injection occurs reducing luminous efficiency
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a first electrode on the substrate, a current distribution control layer, and a second electrode on the active layer. This segmentation allows each layer to perform its specific function, improving electron injection uniformity while maintaining overall structural simplicity.
Solution Approach 2:
The current distribution control layer serves multiple functions simultaneously: it redistributes current to improve uniformity, provides mechanical support, and facilitates electrical connection. This multi-functionality improves luminous efficiency without significantly increasing device complexity.
3Stability of the object's composition
If the substrate is made thicker to maintain structural integrity, then the mechanical integrity is improved, but the light output characteristics deteriorate due to non-uniform current distribution
Solution Approach 1:
The current distribution control layer acts as an intermediary that decouples the relationship between substrate thickness and current uniformity. It allows the substrate to maintain its thickness for structural integrity while the control layer ensures uniform current distribution for optimal light output.
Solution Approach 2:
By changing the resistivity parameter of the control layer, the system achieves uniform current distribution independent of substrate thickness. This allows the substrate to be optimized for mechanical integrity while the control layer optimizes electrical performance for maximum light output.
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 solution enhances electron injection uniformity, maintains high luminous efficiency, and suppresses disturbances in the far field pattern, thereby improving the overall light output characteristics of the semiconductor light-emitting device.
Implementation Method 1
a photonic crystal layer provided on the active layer, the photonic crystal layer including a plurality of protrusions arranged along an upper surface of the active layer
Data Source
AI summary
A surface-emitting semiconductor light-emitting device includes a semiconductor substrate; a first semiconductor layer on a front surface of the semiconductor substrate, an active layer on the first semiconductor layer; a photonic crystal layer on the active layer, a second semiconductor layer on the photonic crystal layer, a first electrode on the second semiconductor layer; and a second electrode on a back surface of the semiconductor substrate. The photonic crystal layer includes a plurality of protrusions arranged along an upper surface of the active layer. The second electrode includes a planar contact portion contacting the back surface of the semiconductor substrate, and at least one fine wire contact portion extending into a surface-emitting region in the back surface of the semiconductor substrate. The light radiated from the active layer is externally emitted from the surface-emitting region. The fine wire contact portion is arranged in the surface-emitting region with rotationally asymmetric.