SSL Point Contacts for Light Extraction
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Solution Overview
Problem
Conventional solid state lighting (SSL) devices have low light extraction efficiencies due to the use of nontransparent conductive materials in their terminals, which hinder the extraction of light generated between contacts, resulting in significant losses.
Innovation Solution
The implementation of point contacts with a large number of small, narrow contact fingers and insulative pads or vias to increase the current spread area ratio, allowing for more efficient light extraction while maintaining adequate electrical performance by forming a plurality of point contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nontransparent conductive materials are used in terminals, then electrical conductivity is improved, but light extraction efficiency deteriorates
Solution Approach 1:
The first terminal is segmented into multiple contact fingers instead of a single continuous contact. This segmentation reduces the total area of nontransparent conductive material covering the light-emitting region, allowing more light to escape while still providing adequate electrical contact points. The contact fingers are distributed across the semiconductor layer to maintain electrical conductivity while minimizing light blocking.
2Loss of energy
If contact area is reduced to improve light extraction, then light extraction efficiency is improved, but electrical performance deteriorates
Solution Approach 1:
The terminal structure implements local quality by having contact fingers with different characteristics in different regions. The contact fingers are positioned to provide adequate electrical contact where needed while leaving other regions open for light extraction. The insulative pads are strategically placed to isolate contact points electrically while allowing light to pass through non-contact areas.
3Reliability
If current density is concentrated in small contact areas, then electrical performance is improved, but light extraction in high-intensity areas deteriorates
Solution Approach 1:
Insulative pads are introduced as intermediary elements between the contact fingers and the underlying semiconductor layer. These pads provide electrical isolation and help distribute the current density more evenly across the contact region, preventing excessive current concentration that would block light extraction. The insulative pads act as mediators that decouple the electrical contact function from the light extraction function.
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 approach enhances light extraction efficiency by directing more light to areas where it can be easily extracted, improving the current density profile and maintaining sufficient electrical performance without excessive reduction in contact area.
Implementation Method 1
The GaN/InGaN MQWs 16 then convert a portion of the electrical energy into light
Data Source
AI summary
Solid state lighting (“SSL”) devices with improved contacts and associated methods of manufacturing are disclosed herein. In one embodiment, an SSL device includes a first semiconductor material, a second semiconductor material spaced apart from the first semiconductor material, and an active region between the first and second semiconductor materials. The SSL device also includes an insulative material on the first semiconductor material, the insulative material including a plurality of openings having a size of about 1 nm to about 20 μm, and a conductive material having discrete portions in the individual openings.