Comparison of precleaning techniques for ZnO atomic layer epitaxy on the sapphire substrate

초록

Atomic layer epitaxy (ALE) is a thin film growth technique allowing atomic-scale thickness control and usually occurs at a lower temperature than chemical vapor deposition (CVD). typically ALE films are extremely smooth and conformal to underlying substrate surface. The ALE techniques produce ZnO films at relatively low temperature [1,2]. In ALE process, surface migration of precursors can be influenced by the process parameters such as DEZn and H2O concentrations and substrate temperature. Moreover, impurities on substrates and reactivity of surfaces are factors that limit the surface diffusion of the precursors. In this work precleaning effects of the substrate on ZnO eptaxial growth were investigated. Dry cleaning techniques including argon, oxygen and hydrogen ECR plasma were employed, respectively, to remove organic contaminants and native oxides on sapphire substrate prior to the growth of the ZnO film by ALE. The cleaning efficiency was assessed by measuring the incubation period for ZnO nucleatino using scanning electron micrography (SEM), and Auger electron emission spectroscopic analysis (AES).