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Graphene-Assisted Quasi-van der Waals Epitaxy of AlN Film on Nano-Patterned Sapphire Substrate for Ultraviolet Light Emitting Diodes
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The Effect of Nitridation on Sputtering AlN on Composited Patterned Sapphire Substrate
Yi Zhang1,2, Guangmin Zhu2, Jiangbo Wang2
1Institute of Optical Engineering, College of Science, Zhejiang University of Technology, No. 288, Liuhe Road, Hangzhou 310023, China.
Materials (Basel, Switzerland)
|February 11, 2023
Summary
We optimized gallium nitride (GaN) growth on patterned sapphire substrates using aluminum nitride (AlN) buffer layers. This method enhances light emission and reduces defects, improving device efficiency.
Area of Science:
- Materials Science
- Semiconductor Physics
- Epitaxial Growth
Background:
- Gallium nitride (GaN) is crucial for optoelectronic devices.
- Patterned sapphire substrates (PSS) are used to improve GaN quality.
- Controlling the initial buffer layer deposition is key for successful GaN epitaxy.
Purpose of the Study:
- To investigate the epitaxial growth of GaN on SiO2-covered cone-shaped PSS.
- To understand the influence of AlN buffer layer deposition conditions on GaN growth modes.
- To optimize nitridation conditions for enhanced photoluminescence and reduced dislocation density.
Main Methods:
- Epitaxial growth of AlN buffer layers on SiO2-PSS using Physical Vapor Deposition (PVD).
- Gallium nitride (GaN) growth under varying alternating radio frequency (RF) power and nitridation times.
- Characterization using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and X-ray Diffraction (XRD).
Main Results:
- Growth mode of GaN is dependent on AlN deposition conditions.
- Low alternating current (AC) power can break SiO2 bonds, enabling GaN growth on pattern sides.
- Photoluminescence (PL) intensity and peak intensity improved by >5% and >15% respectively.
- Screw dislocation density reduced by 65%.
Conclusions:
- Optimized AlN buffer layer deposition and nitridation conditions are critical for high-quality GaN epitaxy on patterned substrates.
- The study demonstrates a method to enhance external quantum efficiency (EQE) of GaN-based devices.
- This work provides insights into controlling GaN growth mechanisms on complex patterned surfaces.
