Micro-LED N-Contact Layout for Uniform Low-Resistance Current Spreading
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Solution Overview
Problem
Micro-LED arrays face challenges in achieving uniform current distribution and resistance due to the small size and high packing density of micro-LEDs, leading to variations in voltage drop and current density across the array.
Innovation Solution
The implementation of individually addressable p-contacts, a low-resistance current spreading layer, and a plurality of n-contacts between the p-contacts and the current spreading layer, which provides a low and uniform resistance electrical path from the n-electrode to the n-type semiconductor layer of each micro-LED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If micro-LED arrays are designed with high packing density and small size, then resolution and brightness are improved, but current distribution uniformity and resistance control deteriorate
Solution Approach 1:
The patent divides the n-type semiconductor layer into multiple discrete n-contacts distributed across the array, with each n-contact serving a specific region. This segmentation allows independent control and optimization of current paths to different micro-LED groups, enabling uniform current distribution even at high packing densities where a single contact would be insufficient.
Solution Approach 2:
The patent introduces a low-resistance current spreading layer as an intermediary between the n-contacts and the n-type semiconductor layer. This intermediate layer facilitates uniform current distribution by spreading the current laterally across the array, compensating for the small size and high density of individual micro-LEDs that would otherwise create non-uniform current paths.
2Reliability
If the number of n-contacts is increased to improve current distribution, then manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the current spreading layer: it serves as both a current distribution pathway and a low-resistance connection medium between n-contacts and the n-type semiconductor layer. This merging reduces the need for additional separate structures, simplifying manufacturing while achieving uniform current distribution across the high-density micro-LED array.
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 configuration reduces the drive voltage, improves the efficiency and light emitting uniformity of micro-LEDs, and enhances the contrast ratio between micro-LEDs in the array.
Implementation Method 1
a metal layer in regions surrounding individual mesa structures of the 2-D array of mesa structures, and a plurality of n-contacts coupling the metal layer to the n-type semiconductor layer
Implementation Method 2
Light emitting diodes (LEDs) convert electrical energy into optical energy
Implementation Method 3
a light-emitting layer in the epitaxial layer stack including an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer
Data Source
AI summary
A light source includes an epitaxial layer stack that includes an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. The epitaxial layer stack includes a two-dimensional (2-D) array of mesa structures formed therein. The light source further includes an array of p-contacts electrically coupled to the p-type semiconductor layer of the 2-D array of mesa structures, a metal layer in regions surrounding individual mesa structures of the 2-D array of mesa structures, and a plurality of n-contacts coupling the metal layer to the n-type semiconductor layer at a plurality of locations between the individual mesa structures of the 2-D array of mesa structures.