Nitride Semiconductor Light Emitting Element Transparent Electrode
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Solution Overview
Problem
Conventional nitride semiconductor light emitting elements with ITO electrodes face issues of high contact resistance and variability in forward voltage due to non-ohmic contact and Schottky barrier formation, leading to inconsistent performance across light emitting elements from the same wafer.
Innovation Solution
A nitride semiconductor light emitting element with a transparent electrode made of indium oxide containing Ge and Si, which forms a good ohmic contact with the p-type nitride semiconductor layer by annealing at 500°C or more under reduced pressure, reducing contact resistance and variability in forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ITO is used as the transparent electrode to improve light extraction efficiency, then light extraction efficiency is improved, but contact resistance increases due to non-ohmic contact and Schottky barrier formation
Solution Approach 1:
The patent changes the compositional parameters of the transparent electrode by adding Ge and Si elements to the ITO base material. This modifies the electronic structure and band alignment between the electrode and p-type nitride semiconductor layer, enabling ohmic contact while preserving optical transparency and light extraction efficiency.
Solution Approach 2:
The patent creates a composite transparent electrode material by combining ITO with GeO2 and SiO2. This composite structure leverages the beneficial properties of each component: ITO provides optical transparency and basic conductivity, while Ge and Si additions tune the electronic properties to achieve ohmic contact with the p-type semiconductor layer.
2Illumination intensity
If ITO is used as the transparent electrode, then light extraction efficiency is improved, but forward voltage variability increases among light emitting elements from the same wafer
Solution Approach 1:
The patent modifies the compositional parameters of the transparent electrode by incorporating Ge and Si elements in specific proportions. This standardizes the electrical properties across the wafer, reducing forward voltage variability while maintaining high light extraction efficiency through optimized optical and electrical parameter balance.
3Reliability
If annealing is performed at 500°C or more under reduced pressure to achieve good ohmic contact, then contact resistance is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent changes the thermal and pressure parameters during the annealing process, specifying temperatures of 500°C or more under reduced pressure conditions. This optimized parameter combination achieves low contact resistance and good ohmic contact while the reduced pressure environment also helps remove volatile contaminants, improving overall contact quality.
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 use of indium oxide with Ge and Si as the transparent electrode material results in a nitride semiconductor light emitting element with low forward voltage variability and improved light output, achieving good ohmic contact and reduced sheet resistance.
Implementation Method 1
annealing the nitride semiconductor light emitting element having the indium oxide layer
Implementation Method 2
the p-type nitride semiconductor layer and the transparent electrode can be in good ohmic contact with each other
Data Source
Figure 1~2
AI summary
An object of the present invention is to provide a nitride semiconductor light emitting element having a novel transparent electrode. The nitride semiconductor light emitting element has the transparent electrode on a p-tyre nitride semiconductor layer, wherein the p-type nitride semiconductor layer and the transparent electrode can be in good ohmic contact to each other and wherein the variability of the forward voltage (Vf) within the wafer can be reduced. The present invention is a nitride semiconductor light emitting element including: an n-side nitride semiconductor layer; a p-side nitride semiconductor layer; and a transparent electrode formed on the p-side nitride semiconductor layer, wherein the transparent electrode is made of indium oxide containing Ge and Si.