Nitride Semiconductor Electrode Layer Inversion for Reflectivity
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Solution Overview
Problem
The challenge in semiconductor light emitting elements is that metallic electrodes absorb light rather than reflecting it, leading to reduced light output and issues with interface characteristics and thermal stability when a reflective metal layer is formed on the semiconductor layer.
Innovation Solution
A method involving a layer inversion phenomenon during heat treatment to form a metal electrode, where a bonding metal layer with a lower density and a reflective metal layer are inverted, enhancing the interface characteristics and thermal stability, and ensuring high reflectivity by uniformly distributing the reflective metal layer on the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective metal layer is formed on the semiconductor layer, then light reflectivity is improved, but interface characteristics deteriorate and contact resistance increases
Solution Approach 1:
The patent divides the metal electrode into multiple layers: a bonding metal layer (first metal layer) and a reflective metal layer (second metal layer). The bonding metal layer forms the interface with the semiconductor layer, while the reflective metal layer provides high reflectivity. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
The bonding metal layer acts as an intermediary between the semiconductor layer and the reflective metal layer. It provides good interface characteristics and low contact resistance with the semiconductor layer, while also serving as a substrate for the reflective metal layer, enabling both functions to coexist.
2Illumination intensity
If a reflective metal layer is formed on the semiconductor layer, then light reflectivity is improved, but thermal stability deteriorates due to agglomeration and interface voids
Solution Approach 1:
By segmenting the electrode structure into a bonding metal layer and a reflective metal layer, the patent prevents the reflective metal layer from directly contacting the semiconductor layer, thereby reducing thermal stress and preventing agglomeration and interface voids formation during heat treatment.
Solution Approach 2:
The patent controls the thickness parameters of each metal layer to optimize performance. The bonding metal layer has a thickness of 50-500 nm and the reflective metal layer has a thickness of 10-100 nm, which are optimized to balance reflectivity, interface characteristics, and thermal stability.
3Reliability
If metallic electrodes are used, then electrical connection is achieved, but light output is reduced due to light absorption
Solution Approach 1:
The patent segments the electrode into a bonding metal layer for electrical connection and a reflective metal layer for light reflection. This segmentation minimizes light absorption by ensuring that the reflective layer is positioned to maximize light reflection while the bonding layer provides necessary electrical contact.
Solution Approach 2:
The patent creates a composite metal electrode structure combining two different metal materials with complementary properties: one metal optimized for electrical bonding and another optimized for optical reflection, achieving both electrical connection and high light output.
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
This approach improves the interface characteristics between the semiconductor layer and the electrode, reduces contact resistance, and enhances thermal stability while maintaining high reflectivity, resulting in increased light output and improved performance of semiconductor light emitting elements.
Implementation Method 1
forming a metal electrode by allowing the bonding metal layer and the reflective metal layer to be inverted through a heat treatment process
Data Source
AI summary
A method for forming a metal electrode and a method for manufacturing semiconductor light emitting elements include providing a substrate having a semiconductor layer formed thereon; forming a bonding metal layer and a reflective metal layer on the semiconductor layer; and forming a metal electrode by layer inversion of the bonding metal layer and the reflective metal layer through a heat treatment process. An interface characteristic between a semiconductor layer and an electrode having a reflective metal layer is enhanced by a layer inversion phenomenon. High reflectivity can be obtained, because a reflection metal layer is uniformly distributed on a semiconductor layer. Further, out-diffusion of a reflective metal layer is prevented through layer inversion to enhance the thermal stability of an electrode. And the number of accepters for generating holes is increased through heat treatment under an oxygen atmosphere, so that contact resistance can be lowered.