LED Parallel Electrode Structure for Current Crowding Reduction
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Solution Overview
Problem
Semiconductor light-emitting devices, such as LEDs, suffer from current-crowding issues that lead to increased forward biasing voltage and reduced light-emitting efficiency, resulting in overheating and decreased reliability due to non-uniform current distribution between electrodes.
Innovation Solution
The implementation of a parallel-connected electrode structure with multiple pads and extending wires, where the distance between pads is greater than 70% of the device width and the distance between extending wires is between 5% and 15% of the device width, providing multiple current paths and reducing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single n-type electrode and a single p-type electrode are used in the light-emitting device, then the device structure is simple, but current crowding occurs leading to non-uniform current distribution and localized overheating
Solution Approach 1:
The patent divides each single electrode into multiple electrodes of the same type. Specifically, the n-type electrode is divided into multiple n-type electrodes, and the p-type electrode is divided into multiple p-type electrodes. This segmentation allows current to be distributed across multiple paths, eliminating current crowding and localized overheating, thereby improving device reliability without significantly increasing structural complexity
Solution Approach 2:
The patent creates multiple copies of electrodes by forming additional n-type and p-type electrodes alongside the original ones. These copied electrodes are positioned to create parallel current paths through the light-emitting layer, ensuring uniform current distribution and preventing thermal accumulation at any single location
2Area of stationary object
If electrodes are positioned close together to reduce device area, then the device size is minimized, but current crowding increases leading to reduced light-emitting efficiency
Solution Approach 1:
By segmenting electrodes into multiple smaller electrodes rather than using one large electrode, the patent achieves both compact area utilization and uniform current distribution. The multiple segmented electrodes are arranged to cover the light-emitting layer effectively, maintaining small device area while preventing current crowding and preserving light-emitting efficiency
Solution Approach 2:
The patent applies different electrode configurations to different regions of the light-emitting layer. By positioning multiple n-type and p-type electrodes at specific locations, the current distribution is optimized locally across different regions, ensuring uniform light-emitting efficiency throughout the device while maintaining compact overall area
3Reliability
If multiple parallel-connected electrodes are implemented to eliminate current crowding, then current distribution becomes uniform and overheating is prevented, but the electrode structure complexity increases
Solution Approach 1:
The patent segments electrodes into multiple units that can be formed using standard semiconductor fabrication processes. This segmentation approach achieves uniform current distribution and improved reliability while maintaining compatibility with existing manufacturing techniques, thus limiting the increase in structural complexity to what is already industrially feasible
Solution Approach 2:
The multiple n-type and p-type electrodes serve dual functions: they provide electrical contacts for current injection and simultaneously act as current distribution networks. This multi-functionality reduces the need for additional specialized structures, thereby limiting the increase in overall device complexity while achieving 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 configuration enhances light-emitting efficiency and reliability by minimizing current-crowding and overheating, requiring a lower power supply and maintaining brightness across the device.
Implementation Method 1
the current is not distributed uniformly between the n-type electrode 44 and the p-type electrode 42, and concentrates at a local region 46 of the light-emitting layer 36
Implementation Method 2
Light is generated through the recombination of holes and electrons that have been injected through the semiconductor layers to the light-emitting region
Implementation Method 3
the distance between the first extending wire and the second extending wire is between 5% and 15% of the width of the light-emitting device
Data Source
AI summary
A light-emitting device includes a substrate; a stacked structure including a first type semiconductor layer positioned on the substrate, a light-emitting structure positioned on the first type semiconductor layer, and a second type semiconductor layer positioned on the light-emitting structure, wherein the stacked structure includes a depression exposing the first type semiconductor layer; a first electrode positioned on the first type semiconductor layer in the depression, the first electrode including at least one first pad and at least one first extending wire with one end connected to the first pad; a second electrode positioned on the second type semiconductor layer, the second electrode including at least one second pad and at least one second extending wire with one end connected to the second pad; wherein the distance between the first pad and the second pad is greater than 70% of the width of the light-emitting device.