GaN Light Emitting Element Stress Management via AlN Buffer Annealing
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Solution Overview
Problem
Current nitride-based semiconductor light-emitting devices face high defect concentrations and reduced internal quantum efficiency due to crystal lattice stress during heteroepitaxial growth, leading to carrier leakage and non-radiative recombination centers.
Innovation Solution
A method involving the deposition of an AlN layer on a substrate, followed by annealing an AlxGa1-xN layer to form an irregular or island-like shape, which reduces stress and improves epitaxial quality by buffering the epitaxial wafer warp, and subsequent deposition of a GaN layer and light-emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heteroepitaxial growth is used on low-cost substrates like sapphire or Si, then manufacturing cost is reduced, but crystal lattice stress causes high defect concentration and reduced internal quantum efficiency
Solution Approach 1:
An AlN buffer layer is introduced as an intermediary between the heterogeneous substrate and the GaN epitaxial layer. This buffer layer mediates the lattice mismatch and reduces crystal stress, thereby lowering defect concentration while maintaining the use of low-cost substrates. The buffer layer acts as a transition zone that improves the quality of the subsequent GaN layer without requiring expensive homoepitaxial substrates.
2Reliability
If a low-temperature GaN buffer layer is formed to gradually eliminate defects, then internal quantum efficiency is improved, but the epitaxial structure still has high defect concentration and remains complex
Solution Approach 1:
The invention changes the material composition parameter by using an AlN buffer layer instead of a low-temperature GaN buffer layer. This parameter change allows for more effective stress relief and defect reduction. Additionally, the use of plasma treatment modifies the surface energy and chemical state of the buffer layer, improving the quality of the subsequent GaN layer without requiring complex multi-layer buffer structures.
3Reliability
If high-quality GaN layers are formed to eliminate defects, then internal quantum efficiency is improved, but manufacturing cost increases due to the need for homoepitaxial substrates
Solution Approach 1:
The AlN buffer layer serves as a mediator that enables high-quality GaN layer growth on low-cost heterogeneous substrates. By introducing this intermediate layer with appropriate lattice parameters, the invention achieves effective stress management and defect reduction, allowing the production of high-efficiency LEDs without the need for expensive GaN homoepitaxial substrates.
Solution Approach 2:
The invention changes the substrate material parameter from expensive GaN homoepitaxial substrates to low-cost sapphire or Si substrates combined with an AlN buffer layer. This parameter change in the substrate system, combined with plasma treatment of the buffer layer, achieves comparable or superior device performance at lower manufacturing cost.
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 effectively eliminates epitaxial layer warp, enhances light-emitting efficiency, and improves wavelength uniformity, reducing product costs and increasing effective output, especially for large-size wafers.
Implementation Method 1
depositing an AlN layer on the substrate surface via PVD
Implementation Method 2
annealing the AlxGa1-xN layer under H2 atmosphere
Implementation Method 3
the stress between different materials is buffered through special thermal treatment
Data Source
AI summary
A method for manufacturing a light emitting element includes: a GaN layer is formed on an AlN-deposited plain or patterned substrate, and the stress between different materials is changed and buffered through thermal treatment of annealing under H2 atmosphere or under H2 and NH3 mixed atmosphere, thus eliminating epitaxial wafer warp caused by such stress and improving epitaxial quality and light-emitting efficiency of the light-emitting element.