UV LED Pillar Contact Layout for Lower Forward Voltage
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Solution Overview
Problem
Existing light-emitting devices, particularly those emitting ultraviolet light, face challenges in achieving efficient light emission and reducing forward voltage due to limitations in semiconductor pillar design and contact layer configurations.
Innovation Solution
The light-emitting device incorporates a substrate with an aluminum nitride buffer layer, a first semiconductor layer of AlxGa(1-x)N, and semiconductor pillars with a second semiconductor layer and an active layer. The device features a unique contact layer configuration with extending portions surrounding the semiconductor pillars and insulating layers with specific openings for electrode contact, optimizing electrical connection and light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional contact layer configurations are used in ultraviolet light-emitting devices, then device structure is simple, but light emission efficiency is low and forward voltage is high
Solution Approach 1:
The contact layer is segmented into multiple functional regions: a first contact layer with a first contact portion and a first extending portion that surrounds the semiconductor pillar, and a second contact layer on the semiconductor pillar. This segmentation allows each region to perform its specific function optimally, improving light emission efficiency while managing device complexity through functional specialization.
Solution Approach 2:
The first contact layer extends in a planar dimension to surround the semiconductor pillar, creating a multi-dimensional contact structure. The first extending portion continuously surrounds the outmost periphery of the semiconductor pillar in top view, adding a lateral dimension to the contact configuration that enhances electrical connection and light extraction efficiency.
2Reliability
If conventional electrode connection structures are used, then manufacturing process is simple, but electrical connection efficiency and light field uniformity are poor
Solution Approach 1:
The insulating layer is configured with local variations: it has first openings that expose the first contact layer and second openings that expose the second contact layer. This local differentiation allows electrical connections to be established at specific locations while maintaining insulation elsewhere, improving electrical connection efficiency and light field uniformity through spatially optimized insulation and conduction paths.
3Power
If standard semiconductor pillar design is used, then device structure is conventional and easy to manufacture, but forward voltage is high and light emission is inefficient
Solution Approach 1:
The semiconductor pillar is nested within the first extending portion of the contact layer. The first extending portion continuously surrounds the outmost periphery of the semiconductor pillar in top view, creating a nested configuration where the contact layer envelops the pillar structure. This nesting improves electrical connection and reduces forward voltage by optimizing the interface between the contact layer and semiconductor pillar.
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 emission efficiency, reduces forward voltage, and improves the uniformity of light field distribution, leading to a more effective ultraviolet light-emitting device.
Implementation Method 1
Light-Emitting Diode (LED) is a solid-state semiconductor light-emitting device... a first semiconductor layer including AlxGa(1-x)N formed on the aluminum nitride (AlN) buffer layer, wherein x>0; a semiconductor pillar formed on the first semiconductor layer, including a second semiconductor layer and an active layer
Data Source
AI summary
A light-emitting device includes a first semiconductor layer; a semiconductor pillar formed on the first semiconductor layer, including a second semiconductor layer and an active layer, wherein the semiconductor pillar comprises an outmost periphery; a first contact layer formed on the first semiconductor layer and including a first contact portion and a first extending portion, wherein the first extending portion continuously surrounds an entirety of the outmost periphery of the semiconductor pillar and the first contact portion; a second contact layer formed on the second semiconductor layer; a first insulating layer including multiple first openings exposing the first contact layer and multiple second openings exposing the second contact layer; a first electrode contact layer connected to the first contact portion through the multiple first openings and covering all of the first contact layer; a second electrode contact layer connected to the second contact layer through the multiple second openings.