ITO Electrode Oxygen Gradient for LED Contact Resistance
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Solution Overview
Problem
The existing semiconductor light emitting devices face challenges in manufacturing high-performance devices due to the low ohmic properties of indium tin oxide (ITO) and the complexity of using metal oxide layers, which complicate the manufacturing process and reduce the utilization of ITO's transmittance.
Innovation Solution
A semiconductor light emitting device structure is developed with a p-electrode comprising a first ITO layer with low oxygen content for low contact resistance and a second ITO layer with higher oxygen content for excellent transmittance, allowing for improved ohmic and transmission properties, and a simplified processing method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal oxide layer made of an element other than In and Sn is provided between ITO and a contact layer to improve contact properties, then the ohmic properties are improved, but the manufacturing process becomes complicated due to different etching conditions
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen content in the ITO layer to achieve different properties in different regions. The ITO layer adjacent to the contact layer has lower oxygen content (30-40 atomic %) for better ohmic contact, while the ITO layer adjacent to the light-emitting layer has higher oxygen content (40-50 atomic %) for better transmittance and etching characteristics. This gradient in oxygen content allows a single material system to provide multiple functions.
Solution Approach 2:
The patent segments the ITO layer into multiple regions with different oxygen contents. The first ITO layer (near contact layer) has lower oxygen content for ohmic contact, while the second ITO layer (near light-emitting layer) has higher oxygen content for transmittance. This segmentation allows each region to be optimized for its specific function while using the same base material system.
2Reliability
If a metal oxide layer made of an element other than In and Sn is provided between ITO and a contact layer to improve transmission properties, then the contact properties are improved, but the transmittance of ITO cannot be utilized as is
Solution Approach 1:
The patent uses parameter changes by varying the oxygen content in different ITO layers. The first ITO layer with lower oxygen content (30-40 atomic %) provides good contact properties, while the second ITO layer with higher oxygen content (40-50 atomic %) maintains excellent transmittance. This allows both contact properties and transmittance to be optimized simultaneously within the same material system.
Solution Approach 2:
The patent applies local quality by giving different oxygen content characteristics to different parts of the ITO structure. The region near the contact layer has lower oxygen content for better contact, while the region near the light-emitting layer has higher oxygen content for better optical transmission. Each local region is optimized for its specific function.
3Illumination intensity
If ITO is used as the p-electrode to extract light, then the transmittance is high, but the ohmic properties are low
Solution Approach 1:
The patent resolves this contradiction by changing the oxygen content parameter in the ITO layer. The first ITO layer adjacent to the contact layer has lower oxygen content (30-40 atomic %) which improves ohmic properties, while the second ITO layer adjacent to the light-emitting layer has higher oxygen content (40-50 atomic %) which maintains high transmittance. This gradient structure allows both requirements to be satisfied.
Solution Approach 2:
The patent segments the ITO electrode into two functional layers: a first ITO layer for ohmic contact with low oxygen content, and a second ITO layer for light transmission with high oxygen content. This segmentation allows each layer to be optimized for its primary function while working together as an integrated electrode structure.
Data Source
AI summary
A semiconductor light emitting device includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer formed between the n-type semiconductor layer and the p-type semiconductor layer, and emitting light. The device further includes a p-electrode contacting to the p-type semiconductor layer, and including a first conductive oxide layer having an oxygen content lower than 40 atomic % and a second conductive oxide layer contacting to the first conductive oxide layer and having a higher oxygen content than the oxygen content of the first conductive oxide layer. The device also includes an n-electrode connecting electrically to the n-type semiconductor layer.