Quality-Improved GaN Epitaxial Layers Grown on Striped Patterned Sapphire Substrates Ablated by Femtosecond Laser

• Main Authors: Yichao Xu, Jun Zou, Xiaoyan Lin, Wenjuan Wu, Wenbo Li, Bobo Yang, Mingming Shi
• Format: Article
• Language: English
• Published: MDPI AG 2018-10-01
• Series: Applied Sciences
• Subjects: GaN (gallium nitride); MOCVD (metal-organic chemical vapor deposition); patterned sapphire substrate; laser ablation
• Online Access: http://www.mdpi.com/2076-3417/8/10/1842

In this work, we propose a new approach to create striped patterned sapphire substrate (PSS) under the circumstance that grooved patterned sapphire substrate technology exhibits more potential to reduce dislocation density in GaN (gallium nitride) epilayers. The striped grooves of patterned sapphire substrate are ablated by femtosecond laser. After the process of metal-organic chemical vapor deposition (MOCVD) method, the c-plane GaN epitaxial layers grown on striped PSS have larger crystallite size, which brings much less crystal boundary. There is much less compressive stress between the GaN crystals which improves the smoothness and compactness of GaN epilayers. This result demonstrates a significant improvement in the crystallinity of the c-plane GaN epitaxial layers grown on striped PSS.