High-temperature growth of epitaxial NiAl thin films on AlAs by molecular-beam epitaxy

Abstract

Good NiAl single‐crystal films were successfully grown on AlAs at high temperature (600 °C) by means of molecular‐beam epitaxy. It was found that there existed three characteristic temperature regions in the crystal growth. Below 300 °C, the in situ formation of NiAl failed. Above 300 °C, NiAl was formed in situ, while other Ni‐Al intermetallic compounds (Ni₃Al₂, NiAl₃, Ni₃Al) also appeared. Above 400 °C, remarkable improvements of the crystallinity, epitaxy, and monocrystallinity were found. The best NiAl film was obtained at 600 °C, where no interfacial disorder attributed to the interdiffusion and no film discontinuity due to balling up were observed. It is suggested that high‐temperature growth is powerful for synthesis of high‐quality NiAl‐(Al,Ga)As heterostructures.