Ti/Ru Laminate Electrode for UV Light Emitting Diodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing light emitting elements face issues with high contact resistance between the Ru electrode and AlxGa1-xN semiconductor layers, leading to increased forward voltage and poor ohmic contact, especially for ultraviolet light emitting elements.
Innovation Solution
A method of manufacturing a light emitting element involving the formation of an n-type semiconductor layer with a Ti/Ru laminate structure, where the Ti layer is in ohmic contact with the n-type semiconductor layer after heat treatment, and the Ru layer provides high reflectance and low contact resistance, optimizing the n-side electrode for low forward voltage and high light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Ru reflective electrode layer is directly connected onto the p-type semiconductor layer, then light reflection efficiency is improved, but contact resistance increases
Solution Approach 1:
The patent applies a composite electrode structure consisting of multiple layers (Ti layer, Ru layer, and optionally Au layer) instead of a single Ru layer. The Ti layer provides low contact resistance with the AlGaN semiconductor layer, while the Ru layer provides high reflectivity for ultraviolet light. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The Ti layer acts as an intermediary between the semiconductor layer and the Ru reflective layer. It forms an ohmic contact with the AlGaN layer while the Ru layer on top provides the reflective function. This intermediary layer resolves the incompatibility between direct Ru contact and low resistance requirements.
2Illumination intensity
If Al composition of the p-type semiconductor layer is increased for ultraviolet light emission, then emission wavelength is improved, but ohmic contact with Ti film becomes difficult
Solution Approach 1:
The patent optimizes the thickness parameter of the Ti layer (0.5-2.5 nm) to achieve proper ohmic contact with high-Al composition AlGaN layers. By carefully controlling this parameter, the patent enables reliable electrical contact while maintaining the high Al composition needed for ultraviolet emission.
Solution Approach 2:
The multi-layer electrode structure (Ti/Ru/Au) is designed to work with high-Al composition AlGaN layers. The Ti layer specifically addresses the contact issue with high-Al content semiconductor, while the Ru and Au layers provide reflective and conductive functions, respectively.
3Reliability
If Ti layer thickness is increased, then ohmic contact is improved, but contact resistance with Ru layer increases
Solution Approach 1:
The patent precisely controls the Ti layer thickness within 0.5-2.5 nm to optimize the balance between forming an ohmic contact with the AlGaN layer and maintaining low resistance at the Ti/Ru interface. This parameter optimization resolves the contradiction between contact quality and resistance.
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 approach results in a light emitting element with reduced forward voltage and enhanced light extraction efficiency due to low contact resistance and high reflectance properties, suitable for ultraviolet light emission.
Implementation Method 1
forming an ohmic contact of the n-type semiconductor layer with the Ti layer by a heat treatment
Implementation Method 2
the Ru layer provides high reflectance and low contact resistance
Implementation Method 3
The Ti layer is formed by sputtering using an RF power source
Data Source
AI summary
A method of manufacturing a light emitting element includes forming an n-type semiconductor layer that includes an n-type clad layer and AlxGa1-xN (0.1≤x≤1) as a main component, forming an n-side contact electrode that includes a laminate structure including a Ti layer and a Ru layer, the Ti layer being in contact with the n-type semiconductor layer, and forming an ohmic contact of the n-type semiconductor layer and the Ti layer by a heat treatment.