High-quality AlN regrown on high-temperature-annealing templates with thermal cleaning

Abstract High-temperature-annealing AlN (HTA-AlN) templates have a large number of Al x O y N z islands which roughen the surface and affect the following regrowth. To achieve smooth and high-quality regrown AlN films, various surface cleaning technologies for HTA-AlN templates were investigated. Conventional alkaline or acidic chemical cleaning has a poor effect on improving the surface of HTA-AlN templates and many V-pits appeared on the regrown-AlN surface. On the other hand, thermal cleaning could remove Al x O y N z islands adequately and thus improve surface morphology. Furthermore, the regrown-AlN layer after thermal cleaning has less than 0.2 nm roughness without any surface defects and maintains high crystallinity as the HTA-AlN templates. This study provides a convenient and effective method for cleaning the HTA-AlN templates, which can be used in the industrialization of AlGaN-based devices.