Enhanced structural and optical properties of semipolar ( 11 2 ¯ 2) AlGaN film with insertion of AlN/AlGaN superlattice

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2023-09, Vol.41 (5)
• Main Authors: Luo, Xuguang, Zhang, Xiong, Fang, Ruiting, Chen, Lin, Xu, Shenyu, Cui, Jia, Lou, Zhiyi, Xu, Yifeng, Wang, Shuchang, Hu, Guohua
• Format: Article
• Language: English
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/6.0002870

The high-quality semipolar ( 11 2 ¯ 2) AlGaN films with high Al contents were successfully deposited on ( 10 1 ¯ 0) m-plane sapphire substrates with the insertion of AlN/AlGaN superlattice (SL) by metal-organic chemical vapor deposition technology. The dependence of structural and optical properties of the ( 11 2 ¯ 2) AlGaN film on the deposition parameters for the inserted AlN/AlGaN SL was investigated extensively premised on the characterization results of the optical microscope, atomic force microscopy, relative optical transmittance spectroscopy, high-resolution x-ray diffraction, and photoluminescence spectroscopy. It was discovered that the insertion of the AlN/AlGaN SL grown under an optimized stabilization time of 10 s between the deposition of AlN and AlGaN sublayers could be used to make significant enhancements in surface morphological characteristics, crystal quality, and optical properties of the ( 11 2 ¯ 2) AlGaN film. The mechanism for the defects reduction in the ( 11 2 ¯ 2) AlGaN film was revealed to be owing to the increase in bending and annihilating probability of the threading dislocations, basal-plane stacking faults, and other structural defects promoted by introducing sufficiently high desorbed Ga atom-induced vacancy concentration in the optimized thermal treatment process.