AlN Template Crystallinity for UV Light-Emitting Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing templates for nitride semiconductor ultraviolet light-emitting elements with AlN layers grown on sapphire substrates face challenges in achieving good crystallinity due to lattice mismatch and difficulty in Al atom migration, limiting the improvement in light emission efficiency.
Innovation Solution
A template with a sapphire substrate having a (0001) plane or an inclined plane is used, where an AlN layer is epitaxially grown with a small average particle diameter and specific orientation, enhancing crystallinity by adjusting growth conditions such as temperature and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an AlN layer is epitaxially grown on a sapphire substrate, then a template for nitride semiconductor ultraviolet light-emitting element is formed, but the crystallinity of the AlN layer is poor due to lattice mismatch and difficulty in Al atom migration
Solution Approach 1:
The patent changes the growth parameters of the AlN layer, specifically controlling the supply timing of source gases (ammonia and aluminum compounds) during epitaxial growth. By adjusting these parameters, the crystallinity of the AlN layer is dramatically improved despite the lattice mismatch with sapphire substrate
Solution Approach 2:
The patent forms AlN crystalline nuclei on the sapphire substrate surface before growing the AlN layer. This preliminary action of creating nucleation sites improves the subsequent epitaxial growth and crystallinity of the AlN layer
2Manufacturing precision
If the crystallinity of the AlN layer is improved by adjusting source gas supply timing, then threading dislocations are reduced, but the growth mode of AlN crystals is not significantly changed and dramatic improvement in crystallinity is not achieved
Solution Approach 1:
The patent employs periodic supply of ammonia gas during the epitaxial growth process. By periodically supplying ammonia alternately with aluminum source gas, the AlN crystals grow with controlled morphology and significantly improved crystallinity, achieving dramatic results beyond conventional continuous supply methods
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 dramatically improves the crystallinity of the AlN layer, leading to enhanced light emission efficiency and characteristics of the nitride semiconductor ultraviolet light-emitting element.
Implementation Method 1
an AlN layer which is directly formed on the main surface and comprises AlN crystals that have an epitaxial crystal orientation relationship with respect to the main surface
Data Source
AI summary
A template includes a sapphire substrate with a (0001) plane or a plane inclined by a predetermined angle with respect to the (0001) plane as a main surface, and an AlN layer composed of AlN crystals having an epitaxial crystal orientation relationship with the main surface directly formed on the main surface of the sapphire substrate. In the template, an average particle diameter of the AlN crystals of the AlN layer at a thickness of 20 nm from the main surface is 100 nm or less.