LED Channel Structure for Ohmic Contact and Light Efficiency
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in achieving high light efficiency and brightness due to high driving voltage issues caused by poor ohmic contact between the n-type electrode and semiconductor layer, which is often exacerbated by the removal of un-doped layers during substrate transfer processes.
Innovation Solution
The implementation of a channel structure formed by reactive ion-beam etching through the semiconductor stack, filled with metal, to establish good ohmic contact between the electrode and the semiconductor layers, along with a substrate transfer process using conductive or thermally conductive substrates, and surface roughening to enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the un-doped layer is removed to form ohmic contact with the n-type semiconductor layer, then the electrical connectivity is improved, but the driving voltage becomes high
Solution Approach 1:
The patent divides the contact structure into multiple segments: the original ohmic contact layer, and a newly formed channel structure penetrating through the n-type semiconductor layer. This segmentation allows the electrical current to travel through a lower-resistance path, improving connectivity without requiring high driving voltage.
Solution Approach 2:
The channel structure acts as an intermediary element between the electrode and the n-type semiconductor layer. By introducing this intermediate conductive pathway, the patent achieves better ohmic contact while avoiding the high driving voltage issue that would result from direct contact after un-doped layer removal.
2Ease of manufacture
If a conventional substrate transfer process is used, then the manufacturing process is simple, but the light efficiency and brightness are limited
Solution Approach 1:
The patent applies local quality improvement by selectively forming the channel structure only in the n-type semiconductor layer region where ohmic contact is needed. The channel structure provides enhanced electrical connectivity locally without affecting the overall simplicity of the substrate transfer process, thereby improving light efficiency while maintaining ease of manufacture.
3Reliability
If the n-type semiconductor layer is etched to form a channel, then the ohmic contact is improved, but the device structure becomes more complex
Solution Approach 1:
The patent transitions from a planar contact structure to a three-dimensional channel structure that penetrates vertically through the n-type semiconductor layer. This dimensional change allows the channel to establish electrical connectivity through the thickness of the layer, improving ohmic contact while the channel's straightforward vertical geometry minimizes additional structural 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 approach reduces driving voltage, improves light efficiency, and extends the lifespan of LEDs by ensuring better electrical connectivity and enhanced light extraction, resulting in improved performance and efficiency.
Implementation Method 1
The reactive ion-beam etching process is applied to form a channel penetrated the semiconductor stack
Implementation Method 2
The light efficiency of the light-emitting device is increased by the roughened surface describe above
Data Source
AI summary
A light-emitting device comprises a channel structure in the semiconductor layer for connecting an electrode and an ohmic contact layer by means of a substrate transfer process including a wafer-bonding process and a substrate-lifting-off process. The channel structure is formed in the semiconductor stack for electrically connecting the ohmic contact layer and the electrode and driving the current into the light-emitting device. Thereby, a horizontal type or a vertical type of light-emitting device has a good ohmic contact and high light efficiency.