Light-Emitting Element Electrodes for Uniform End Surface Roughness
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Solution Overview
Problem
Existing light-emitting elements often have uneven surface roughness at their end portions, leading to non-uniform characteristics and reduced performance in display devices.
Innovation Solution
A light-emitting element with ohmic electrodes at both end portions, where one surface exposed from the electrodes has constant surface roughness, ensuring uniform characteristics. The element includes a first and second semiconductor layer, an active layer, and electrodes formed through a specific manufacturing method involving substrates and lift-off techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for light-emitting elements, then production is simpler and faster, but the surface roughness at end portions becomes uneven leading to non-uniform characteristics
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the semiconductor layer before electrode deposition, and by designing the electrode structure with specific surface treatments in advance. This ensures that the end portions maintain constant surface roughness throughout the manufacturing process, preventing the unevenness that would otherwise occur during subsequent processing steps.
Solution Approach 2:
The patent implements local quality by creating different surface characteristics at different locations of the light-emitting element. Specifically, the end portions are given constant surface roughness through protective films and surface treatments, while other regions maintain their original characteristics. This localized differentiation ensures uniform electrical contact at the electrodes without affecting the overall device structure.
2Reliability
If end portions have uneven surface roughness, then manufacturing is easier, but contact reliability between light-emitting elements and contact electrodes deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the surface roughness parameter at the end portions to be constant, rather than allowing it to vary as in conventional designs. This is achieved through protective films and surface treatments that control the roughness parameter, ensuring optimal contact reliability with external electrodes while maintaining manufacturing feasibility.
3Manufacturing precision
If surface roughness is made constant at end portions, then luminous efficiency uniformity improves, but manufacturing process becomes more complex
Solution Approach 1:
The patent introduces intermediary elements such as protective films and surface treatment layers that mediate between the semiconductor layer and external electrodes. These intermediaries enable constant surface roughness at the end portions, ensuring uniform luminous efficiency, while simplifying the overall manufacturing process by providing a standardized interface for electrode connection.
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
The solution achieves uniform luminous efficiency and improved contact reliability between the light-emitting elements and contact electrodes, enhancing the overall performance and lifespan of display devices.
Implementation Method 1
removing the first substrate using a laser lift-off method to expose the first electrode
Implementation Method 2
forming an adhesive layer on the buffer layer and arranging a second substrate on the adhesive layer to bond the first substrate and the second substrate
Data Source
AI summary
A light-emitting element includes a first end portion and a second end portion disposed in a length direction of the light-emitting element, a first electrode corresponding to the first end portion, a first semiconductor layer on the first electrode, an active layer on the first semiconductor layer, a second semiconductor layer on the active layer, and a second electrode on the second semiconductor layer and corresponding to the second end portion. The second electrode includes a first layer on the first semiconductor layer, and a second layer on the first layer. The first semiconductor layer includes a p-type semiconductor layer doped with a p-type dopant. The second semiconductor layer includes an n-type semiconductor layer doped with an n-type dopant. The first electrode is in ohmic contact with the first semiconductor layer. The second electrode is in ohmic contact with the second semiconductor layer.