Roughened LED Electrode Contact Area and Voltage Reduction
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face challenges in reducing operation voltage and improving optical output efficiency and reliability due to limited contact area and adhesion between electrode layers and semiconductor layers.
Innovation Solution
A light emitting device with a first electrode layer having a roughness that increases contact area with the first conduction type semiconductor layer, accompanied by an insulating layer to enhance adhesion and reduce resistance, thereby improving operation voltage and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional smooth contact electrode is used, then the manufacturing process is simple, but the contact area with the semiconductor layer is limited resulting in high resistance and high operation voltage
Solution Approach 1:
The patent applies parameter changes by modifying the surface morphology parameter of the contact electrode from smooth to rough. This roughness increases the contact area between the electrode and semiconductor layer, thereby reducing contact resistance and improving adhesion without fundamentally changing the electrode's material composition or overall structure
Solution Approach 2:
The patent implements preliminary action by forming the roughness structure on the contact electrode surface before final assembly. This pre-formed roughness ensures optimal contact area and adhesion from the outset, preventing subsequent issues with high resistance and improving device reliability before operation begins
2Reliability
If the contact area between electrode and semiconductor layer is increased, then resistance decreases and operation voltage improves, but the device complexity increases
Solution Approach 1:
The patent changes the surface topology parameter of the contact electrode to create roughness, which directly increases the contact area with the semiconductor layer. This parameter modification enhances adhesion strength and reduces resistance while maintaining a relatively simple overall device structure
Solution Approach 2:
The patent applies dimensionality change by transitioning the contact electrode surface from a two-dimensional smooth plane to a three-dimensional rough surface with increased surface area. This dimensional transformation increases contact area and adhesion without significantly increasing the electrode's footprint or overall device complexity
3Use of energy by moving object
If the operation voltage is reduced to improve optical output efficiency, then the optical output efficiency increases, but it requires increased contact area which complicates the electrode design
Solution Approach 1:
The patent reduces operation voltage by modifying the contact electrode's surface parameter to create roughness. This increases contact area and reduces contact resistance, thereby lowering operation voltage and improving optical output efficiency while keeping the electrode design relatively simple
Solution Approach 2:
The patent converts what would normally be considered a disadvantage (increased surface complexity) into a benefit by using controlled roughness to reduce operation voltage. The increased surface area, which might seem to complicate design, actually simplifies the overall system by enabling lower operating voltages and improved efficiency
Data Source
AI summary
A light emitting device includes a light emitting structure including a second conduction type semiconductor layer, an active layer, and a first conduction type semiconductor layer, a second electrode layer arranged under the light emitting structure, a first electrode layer having at least portion extending to contact the first conduction type semiconductor layer passing the second conduction type semiconductor layer and the active layer, and an insulating layer arranged between the second electrode layer and the first electrode layer, between the second conduction type semiconductor layer and the first electrode layer, and between the active layer and the first electrode layer, wherein said at least one portion of the first electrode layer contacting the first conduction type semiconductor layer has a roughness.