Effects of the high-temperature-annealed self-buffer layer on the improved properties of ZnO epilayers grown by helicon-wave-excited-plasma sputtering epitaxy on a-plane sapphire substrates

摘要

The use of the high-temperature-annealed self-buffer layer (HITAB) enabled to observe free A-and B-exciton emissions at 9 K from ZnO heteroepitaxial films grown by the sputtering epitaxy method using a helicon-wave-excited plasma on uniaxially nearly lattice-matched (1120) A1_2O_3 substrates. The result was correlated with a twofold decrease in the densities of threading dislocations having both the screw and edge components, according to the dislocation concealing in ZnO HITAB due to lateral mass transport of low-temperature deposited ZnO nanocrystalline grains during high temperature annealing.