Fingered Electrode Trench Light-Emitting Device
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Solution Overview
Problem
Conventional nitride-based light-emitting devices suffer from current crowding and low light efficiency due to the design of electrodes, leading to reduced device lifespan and performance.
Innovation Solution
The light-emitting device features a substrate with a light-emitting stack, a trench exposing part of the first layer, and conductive structures with electrodes and pads of specific areas and shapes to optimize current injection and light extraction, including spiral or fingered electrode designs to interdigitate and reduce light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional p-type transparent electrode is used close to the n-type electrode, then current injection is achieved, but current crowding occurs and light-emitting efficiency deteriorates
Solution Approach 1:
The p-type electrode is segmented into multiple fingered electrodes (first, second, third, and fourth fingered electrodes) that are distributed across the light-emitting device. This segmentation allows current to be injected through multiple locations rather than concentrated at one point, reducing current crowding while maintaining effective current injection into the light-emitting layer.
Solution Approach 2:
The electrode design transitions from a single-point or simple pad configuration to a multi-dimensional fingered structure that extends across the device surface. The fingered electrodes are arranged in specific patterns (with certain distances between them) to optimize current distribution across the two-dimensional light-emitting area, improving both current injection and light extraction efficiency.
2Power
If the p-type electrode area is increased to improve current injection, then current spread is enhanced, but light absorption by the electrode increases
Solution Approach 1:
The electrode is divided into multiple separated fingered segments rather than one large continuous area. This allows the total electrode area to be optimized for current injection while the segmented structure reduces continuous light absorption paths, as light can pass through the gaps between fingers rather than being absorbed across a large continuous metal area.
Solution Approach 2:
Different regions of the device have different electrode configurations optimized for their local functions. The fingered electrodes are positioned and dimensioned to provide sufficient current injection capability where needed while minimizing light absorption in regions where light extraction is critical. The spacing and dimensions of individual fingers are optimized for their specific locations.
3Device complexity
If conventional electrode design is used, then device structure is simple, but current crowding causes high temperature and reduced device lifespan
Solution Approach 1:
The electrode structure is segmented into multiple fingered elements with specific spacing, which distributes current injection across multiple locations. This reduces current density at any single point, minimizing localized heating and improving device reliability and lifespan, while the overall structure remains relatively simple to manufacture.
Solution Approach 2:
The electrode design utilizes a two-dimensional fingered pattern arrangement rather than simple one-dimensional or point contacts. This dimensional approach allows current to be distributed across the device surface in a controlled manner, reducing hot spots and improving thermal management, thereby enhancing device reliability without excessive complexity.
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 design enhances light-emitting efficiency and device lifespan by ensuring sufficient current injection and reducing heat buildup, thereby improving the overall performance of the light-emitting device.
Implementation Method 1
Electrons and holes recombine in the light-emitting layer 13 and then produce photons
Data Source
AI summary
A light-emitting device comprises a substrate, an epitaxial structure formed on the substrate including a first semiconductor layer, a second semiconductor layer, and a light-emitting layer formed between the first semiconductor layer and the second semiconductor layer. A trench is formed in the epitaxial structure to expose a part of side surface of the epitaxial structure and a part of surface of the first semiconductor layer, so that a first conductive structure is formed on the part of surface of the first semiconductor layer in the trench, and a second conductive structure is formed on the second semiconductor layer. The first conductive structure includes a first electrode and a first pad electrically contacted with each other. The second conductive structure includes a second electrode and a second pad electrically contacted with each other. Furthermore, the area of at least one of the first pad and the second pad is between 1.5×104 μm2 and 6.2×104 μm2.