No abstract

We examined the epitaxial growth of ZnO films on a sapphire (0001) substrate by an atmospheric pressure atomic layer epitaxy technique using ZnCl 2 and O 2 sources. The films were deposited epitaxially in a substrate temperature range of 450-550°C with a constant growth rate of 0.26 nm/cycle. It is noteworthy that the rate corresponds to just a half-length of the c axis of hexagonal ZnO, indicating that the alternate deposition of ZnCl 2 and O 2 on the substrate is governed by a self-limiting mechanism. This was also confirmed by the facts that the film thickness was dependent only on the growth cycles and that the surface was quite smooth. A strong photoluminescence band edge emission of 3.36 eV was observed at 20 K.

Thin films of ZnO were grown on a sapphire(0001) substrate by atmospheric pressure halide vapor phase epitaxy. A double-crystal X-ray diffraction study showed a minimum full width at half maximum of the hexagonal ZnO(0002) line after 1212 s for the film deposited at 1023 K. The room-temperature photoluminescence spectrum displays an ultraviolet emission at 381.0 nm due to the recombination of free excitons.