Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8148354 | Journal of Crystal Growth | 2018 | 21 Pages |
Abstract
AlN epilayer properties (120â¯nm thick) grown by ammonia assisted molecular beam epitaxy on c-sapphire substrates with different low temperature AlN buffer layers (LT-BL) have been studied. The role of the LT-BL on the AlN structural and optical properties was investigated as a function of the LT-BL thickness and growth temperature. Optimum growth conditions were identified with LT-BL thickness of 3â¯nm and growth temperature between 480â¯Â°C and 520â¯Â°C. It was shown that by optimizing these conditions, a reduction of both mixed and edge threading dislocation densities up to 75% is achieved. The impact of the growth temperature of the AlN epilayer was also studied showing an additional improvement of the AlN crystal and morphological properties while growing at higher temperature. A correlation between the epilayer strain and the PL emission was also investigated. Finally, an Al0.7Ga0.3N:Si doped layer was grown on the top of the optimized AlN template showing a smooth surface with monoatomic steps and a roughness â¼0.2â¯nm, confirming the potential of such templates for the fabrication of AlGaN based heterostructures.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Samuel Matta, Julien Brault, Maxim Korytov, Thi Quynh Phuong Vuong, Catherine Chaix, Mohamed Al Khalfioui, Philippe Vennéguès, Jean Massies, Bernard Gil,