Atmospheric pressure atomic layer epitaxy of ZnO using a chloride source

We examined the epitaxial growth of ZnO films on a sapphire (0001) substrate by an atmospheric pressure atomic layer epitaxy technique using ZnCl2 and O-2 sources. The films were deposited epitaxially in a substrate temperature range of 450-550 degreesC 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 ZnCl2 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.