UV LED Transparent Electrode Using Resistive Switching Material
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Solution Overview
Problem
Current transparent electrodes used in UV LEDs suffer from low transmittance and poor ohmic contact with semiconductor layers, limiting their efficiency and practical application due to the trade-off between conductivity and transmittance, and existing alternatives like silver thin films do not significantly improve transmittance in the UV wavelength range.
Innovation Solution
A light emitting device utilizing a transparent electrode formed from a resistance change material that changes from a high to a low resistance state upon applying a threshold voltage, allowing for high transmittance in both UV and visible wavelength ranges and achieving good ohmic contact with semiconductor layers, along with a current spreading layer using CNT or graphene to prevent current concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ITO transparent electrode is used in UV LED, then the device can be manufactured with current technology, but the transmittance of UV light is greatly decreased to 1% or less
Solution Approach 1:
The patent changes the material parameters by replacing ITO with ZnO-based transparent electrode material that has different optical and electrical properties, specifically higher transmittance in UV range while maintaining manufacturability through standard deposition processes
Solution Approach 2:
The patent uses composite material structure combining ZnO with Al doping (AlGaN) to achieve both high transmittance and good ohmic contact, creating a material that balances optical and electrical requirements
2Ease of manufacture
If metal electrode pad is directly formed on semiconductor layer, then manufacturing is simplified, but ohmic contact is poor due to large work function difference
Solution Approach 1:
The patent introduces ZnO transparent electrode as an intermediary layer between the metal electrode pad and semiconductor layer, mediating the electrical contact to achieve ohmic contact while maintaining manufacturing simplicity
Solution Approach 2:
The patent changes the work function parameter by using ZnO with appropriate doping levels to match the semiconductor layer, enabling ohmic contact without complex multi-layer structures
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 provides high transmittance in the UV wavelength range and good ohmic contact characteristics, enhancing the efficiency of UV LEDs by allowing current to spread evenly across the semiconductor layer, thereby improving light emission and reducing current concentration issues.
Implementation Method 1
a transparent insulating material of which resistance state is changed from a high resistance state into a low resistance state according to an applied electric field
Implementation Method 2
most of light in a UV wavelength range of 10 nm to 320 nm generated in an activation layer is absorbed by an ITO layer, so that only about 1% of the light can be transmitted through the ITO layer
Implementation Method 3
current is concentrated on a metal electrode pad, but current is not supplied into the entire activation layer
Data Source
AI summary
Provided are a light emitting device including a transparent electrode having high transmittance with respect to light in a UV wavelength range as well as in a visible wavelength range and good ohmic contact characteristic with respect to a semiconductor layer and and a method of manufacturing the light emitting device. A transparent electrode of a light emitting device is formed by using a resistance change material which has high transmittance with respect to light in a UV wavelength range and of which resistance state is to be changed from a high resistance state into a low resistance state due to conducting filaments, which current can flow through, formed in the material if a voltage exceeding a threshold voltage inherent in a material applied to the material, so that it is possible to obtain high transmittance with respect to light in a UV wavelength range.