Micro LED Electrode Layout With Protected Ohmic Contact
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Solution Overview
Problem
Conventional micro light-emitting diode (LED) electrode designs are prone to damage during manufacturing, leading to reduced light-emitting efficiency due to the limited position and size of the ohmic contact layer, which affects the internal quantum efficiency and external light extraction efficiency.
Innovation Solution
Incorporating a current conducting layer between the conductive pad and the ohmic contact layer, which serves as an etching protection layer, allowing for misalignment and increased freedom in positioning the ohmic contact layer, thereby reducing contact resistance and enhancing light-emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ohmic contact layer is disposed directly below the conductive pad, then the electrode structure is compact, but the ohmic contact layer is damaged during the manufacturing process when the insulating layer is being etched
Solution Approach 1:
The patent introduces a current conducting layer as an intermediary component between the conductive pad and the ohmic contact layer. This intermediate layer serves as a protective barrier during the etching process of the insulating layer, preventing direct exposure and damage to the ohmic contact layer while maintaining electrical conductivity. The current conducting layer acts as a mediator that resolves the conflict between structural compactness and manufacturing reliability.
2Ease of manufacture
If the ohmic contact layer position is constrained by the conductive pad size and position, then the electrode connection is direct, but the positioning freedom is limited
Solution Approach 1:
The patent extends the electrode structure into a new dimensional space by introducing the current conducting layer that can extend beyond the conductive pad boundaries. This allows the ohmic contact layer to be positioned more freely on the current conducting layer surface without being constrained by the conductive pad's size and position, thereby increasing positioning freedom while maintaining simple direct connection through the vertical stack.
3Manufacturing precision
If the ohmic contact layer is positioned close to the conductive pad, then the contact resistance is low, but the forward bias increases due to limited positioning freedom
Solution Approach 1:
The patent utilizes the extended current conducting layer to optimize the spatial arrangement of ohmic contact layers. By positioning ohmic contact layers on different sides of the active layer with increased freedom provided by the extended current conducting layer, the distance between opposing ohmic contact layers is reduced, which lowers the forward bias while maintaining low contact resistance through proper alignment with the conductive pad.
Data Source
AI summary
A micro light-emitting diode including an epitaxy structure, a first pad, a first ohmic contact layer and a current conducting layer is provided. The epitaxy structure includes a first type semiconductor layer, a second type semiconductor layer and an active layer. The first pad is electrically connected to the first type semiconductor layer. The first ohmic contact layer is electrically connected between the first type semiconductor layer and the first pad. The current conducting layer is electrically connected between the first ohmic contact layer and the first pad. At least a portion of the orthogonal projection of the first ohmic contact layer on the plane upon which the first type semiconductor layer is located is away from the orthogonal projection of the first pad on the plane. A display panel is also provided.