Metal-Mesh Semiconductor Contacts for LED Current Spreading
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Solution Overview
Problem
Conventional semiconductor contacts in LEDs inhibit uniform current spreading and block light extraction due to high resistance, making it challenging to achieve efficient current injection and light emission, especially in mid-infrared and ultraviolet spectra.
Innovation Solution
The use of composite metal-mesh semiconductor contacts and cascaded LED light emission junctions to reduce spreading resistance and increase injection resistance, allowing for improved current distribution and light extraction by optimizing mesh geometry and material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-resistance metal contact layer is used to spread current uniformly across the junction surface, then current spreading is improved, but light extraction is blocked
Solution Approach 1:
The continuous metal contact layer is segmented into a mesh structure with discrete conductive lines separated by openings. This segmentation allows current to spread through multiple parallel paths while leaving gaps for light extraction, resolving the contradiction between current uniformity and light transmission
Solution Approach 2:
The mesh structure creates different local properties: metal regions provide low resistance for current spreading, while opening regions provide high transparency for light extraction. This spatial variation in material properties allows both functions to coexist without compromise
2Reliability
If the metal contact coverage is increased to reduce spreading resistance, then current injection is improved, but light extraction efficiency decreases
Solution Approach 1:
The mesh contact divides the metal coverage into discrete elements distributed across the surface, providing sufficient total coverage for current injection while maintaining local transparency regions for light extraction
Solution Approach 2:
The contact structure combines metal conductive elements with transparent semiconductor material in a composite mesh architecture, leveraging the electrical conductivity of metal and the optical transparency of semiconductor to achieve both low spreading resistance and high light extraction
Data Source
AI summary
An optoelectric device can comprise a substrate and at least one junction configured to provide an active region within the substrate. Additionally, the device can comprise a metal-mesh semiconductor electrical contact structure attached to a surface of the substrate. The metal-mesh semiconductor electrical contact structure can further comprise a mesh line width, a mesh opening size, and a mesh thickness.