Rare-Earth Nitride Priming Layer for Flat Off-Angle GaN Growth
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Solution Overview
Problem
The formation of nitride semiconductor layers on off-angle inclined substrates often results in macro steps due to piezo polarization and strain, leading to suboptimal device characteristics, and the addition of indium can introduce lattice strain and crystal defects, making it difficult to achieve high-quality semiconductor devices.
Innovation Solution
The use of a rare earth element, such as Eu, added to the nitride semiconductor layer as a surfactant to prevent macro step formation, providing a flat surface and inhibiting Ga atom diffusion, thereby avoiding continuous addition requirements and lattice strain, and allowing for high-quality semiconductor device production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If indium is added to the nitride semiconductor layer to improve light emission efficiency, then light emission efficiency is improved, but lattice strain and crystal defects occur
Solution Approach 1:
The patent changes the chemical composition parameter by substituting indium with rare earth elements (Eu, Er, Tm, Ho, Dy) in the nitride semiconductor layer. This parameter change maintains light emission efficiency while avoiding the lattice strain and crystal defects caused by indium addition, as the rare earth elements have ionic radii closer to gallium and do not cause significant lattice distortion.
2Use of energy by moving object
If off-angle inclined substrate is used to reduce crystal defect density and improve light emission efficiency, then light emission efficiency is improved, but macro steps appear due to step bunching mechanism
Solution Approach 1:
The patent applies local quality by forming a specific rare earth element-containing layer (1 nm to 10 nm thick) at the interface between the substrate and the nitride semiconductor layer. This localized rare earth element addition modifies the surface properties locally to prevent step bunching and macro step formation, while maintaining the overall off-angle substrate configuration that provides improved light emission efficiency.
3Shape
If continuous addition of indium is performed to remove macro step, then macro step is removed, but process complexity and manufacturing difficulty increase
Solution Approach 1:
The patent implements preliminary action by incorporating rare earth elements into the nitride semiconductor layer during the initial crystal growth process on the off-angle substrate. This preliminary incorporation of rare earth elements prevents macro step formation from the beginning, eliminating the need for subsequent continuous indium addition or post-growth processing to remove macro steps, thereby simplifying the manufacturing process.
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 Eu-added nitride layer effectively prevents macro step formation, enabling the production of high-quality nitride semiconductor devices with improved light emission efficiency and reduced crystal defects, suitable for both light emitting and high-frequency/high-power applications.
Implementation Method 1
The use of a rare earth element, such as Eu, added to the nitride semiconductor layer as a surfactant to prevent macro step formation, providing a flat surface and inhibiting Ga atom diffusion
Data Source
AI summary
The purpose of the present invention is to provide a technique of manufacturing a nitride semiconductor layer with which, when producing a semiconductor device by forming a nitride semiconductor layer on off-angle inclined substrate, it is possible to stably supply high-quality semiconductor devices by preventing occurrence of a macro step using a material that is not likely to occur lattice strains or crystal defects by mixing with GaN and does not require continuous addition; and provided is a nitride semiconductor device which comprises a nitride semiconductor layer formed on a substrate, wherein the substrate is inclined at an off angle, a rare earth element-added nitride layer to which a rare earth element is added is formed on the substrate as a primed layer, and a nitride semiconductor layer is formed on the rare earth element-added nitride layer.