LED Module with Segmented Pads and Barrier Layers
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Solution Overview
Problem
Conventional LED modules suffer from current crowding and metal diffusion issues due to cracks in the barrier layer, leading to degraded electrical properties and reduced luminance, especially in high-voltage or high-current applications.
Innovation Solution
The proposed LED module incorporates a stacked structure with a reflective metal layer and a conductive barrier layer, where the conductive barrier layer is formed with a thickness varying based on the underlying layer, and a pad barrier layer is used to prevent metal diffusion, along with patterned insulating layers to form pads that reduce current crowding and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a p-type pad is electrically connected to the entire surface of p-GaN exposed by an insulating layer, then electrical contact area is increased, but current crowding occurs
Solution Approach 1:
The p-type pad is divided into multiple separate pad regions instead of a single continuous pad. These segmented pads are distributed across the exposed p-GaN surface, which prevents current crowding by distributing the current flow across multiple discrete contact points while still providing adequate total electrical contact area.
Solution Approach 2:
The insulating layer is selectively removed or thinned in specific regions to create local variations in the electrical contact properties. This allows different areas of the p-GaN surface to have different contact characteristics, optimizing current distribution while maintaining sufficient total contact area.
2Illumination intensity
If a reflection layer is introduced on the semiconductor layer to reflect light, then light emission efficiency is improved, but metal diffusion occurs through cracks in the barrier layer
Solution Approach 1:
A barrier layer is formed on the reflection layer before the reflection layer is deposited, or the barrier layer is reinforced in advance. This preliminary protective measure prevents metal diffusion from occurring even when cracks develop in the barrier layer during subsequent processing or operation.
Solution Approach 2:
An additional protective barrier layer or intermediate layer is introduced between the reflection layer and the semiconductor layer. This intermediary layer acts as a secondary barrier to metal diffusion, preventing metal atoms from migrating through cracks in the original barrier layer and degrading electrical properties.
3Reliability
If the barrier layer thickness is increased to prevent metal diffusion, then metal diffusion is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The barrier layer thickness is varied spatially, being thicker in regions where metal diffusion risk is highest (such as near the reflection layer interfaces) and thinner in other regions. This localized approach provides effective metal diffusion prevention while minimizing the overall material usage and manufacturing complexity.
Solution Approach 2:
Multiple barrier layer materials with different properties are combined in a stacked configuration. This composite barrier structure provides enhanced metal diffusion prevention through the synergistic effects of different materials, allowing thinner overall barrier thickness while maintaining or improving protection effectiveness.
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 solution effectively prevents current crowding and metal diffusion, maintaining high conductivity and electrical contact, while also allowing for improved light reflection and emission by controlling the thickness and pattern of the insulating layers.
Implementation Method 1
a reflection layer formed of a metal is introduced on the semiconductor layer or a current spreading layer, and light is reflected by the reflection layer
Implementation Method 2
a barrier layer is provided on the reflection layer. The barrier layer is provided to prevent diffusion of the metal forming the reflection layer
Implementation Method 3
A light emitting diode (LED) is a device including an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed between the n- and p-type semiconductor layers. When a forward electric field is applied to the n- and p-type semiconductor layers, electrons and holes may be injected into the active layer and recombine in the active layer to emit light
Data Source
AI summary
Provided is a light emitting diode (LED) in which a side surface of a reflective metal layer has a predetermined angle, and occurrence of cracks in a conductive barrier layer formed on the reflective metal layer can be prevented. Also, an LED module using LEDs is disclosed. A reflection pattern electrically connected to a second semiconductor layer is partially exposed by patterning a first insulating layer. Accordingly, a first pad is formed through the partially opened first pad region. Also, a conductive reflection layer electrically connected to a first semiconductor layer forms a second pad region formed by patterning a second insulating layer. A second pad is formed on the second pad region.