Epitaxy of Al films on GaN studied by reflection high-energy electron diffraction and atomic force microscopy

摘要

Epitaxy of A1 films deposited on GaN has been studied using reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM), x-ray diffraction, and ion channeling techniques. A1 (111) films have been found to grow epitaxially on GaN (0001) surfaces with Al 〈211〉‖GaN〈2110〉. For growth at 15 and 150 ℃ with a deposition rate of 0.26Anstrom/s, the epitaxial quality of the film was poor initially, as evidenced by the observation of diffuse RHEED patterns. After a few monolayers, a sharp and streaky RHEED pattern develops and is maintained during subsequent deposition, indicating an improvement in epitaxial quality with a 'two-dimensional growth mode. AFM studies indicate that the initial GaN surface quality is a significant factor in achieving epitaxial growth, and that the size of Al epitaxial islands increases substantially for higher growth temperatures. X-ray diffraction and ion channeling results confirm the epitaxial nature of the Al films in spite of a significant lattice mismatch of 10.2. # 1997American Institute of Physics, S0003-6951 (97)04208-3