LED Electrode Pad Segmentation for Uniform Current Spreading
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Solution Overview
Problem
High voltage and high efficiency light-emitting diodes face challenges with current crowding and reduced light extraction efficiency due to uneven current distribution and defects in large LED sizes, leading to reliability issues and optical losses.
Innovation Solution
A light-emitting diode design featuring a group of first and second light-emitting cells connected in parallel, with shared semiconductor layers and optimized electrode and extension structures for uniform current spreading, reducing current crowding and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent electrode layer is formed on the P-type semiconductor layer to enhance current spreading, then current distribution is improved, but light absorption increases due to the electrode layer's thickness
Solution Approach 1:
The patent divides the electrode structure into multiple segments: a first electrode pad, a first extension extending from it, a second electrode pad, and a second extension. This segmentation allows current to spread through multiple distributed contact points rather than a single thick electrode layer, reducing light absorption while maintaining current spreading effectiveness.
Solution Approach 2:
The patent transitions from a two-dimensional electrode layer approach to a three-dimensional extension structure that protrudes from the semiconductor layer surface. These extensions create additional current pathways in the vertical dimension, improving current spreading without requiring a thick transparent electrode layer that would absorb light.
2Area of moving object
If LED size is increased to provide larger light emitting area, then luminous output is improved, but defect likelihood increases leading to non-uniform current spreading
Solution Approach 1:
The patent segments the current injection structure into multiple distributed extensions that contact the semiconductor layer at various locations. This segmentation creates multiple independent current pathways, so that even if defects exist in one region, current can still spread uniformly through other pathways, maintaining reliability in large-area LEDs.
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 design ensures uniform current distribution, improves light extraction efficiency, and increases the reliability of high voltage light-emitting diodes by reducing defects and optical losses.
Implementation Method 1
A transparent electrode layer having a low resistivity may be formed on the P-type semiconductor layer to enhance current spreading. In this structure, electric current supplied from the P-electrode pad may be dispersed by the transparent electrode layer before entering the P-type semiconductor layer
Implementation Method 2
Gallium nitride (GaN) based light emitting diodes (LEDs) have been used in a wide range of applications including full color LED displays, LED traffic signals, and white LEDs
Data Source
AI summary
A light-emitting diode includes at least two light emitting cells disposed on a substrate and spaced apart from each other, wherein each of the at least two light emitting cells includes a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer. Each of the at least two light emitting cells includes a cathode disposed on the first conductivity-type semiconductor layer, an anode disposed on the second conductivity-type semiconductor layer, and the cathode of a first light emitting cell of the at least two light emitting cells is electrically connected in series to the anode of a second light emitting cell of the at least two light emitting cells adjacent to the first light emitting cell by an interconnecting section.