Reflection High-Energy Electron Diffraction Oscillation during CaF2 Growth on Si(111) by Partially Ionized Beam Epitaxy

We have observed reflection high-energy electron diffraction (RHEED) intensity oscillation in the growth of single-crystalline CaF2 on Si(111) by partially ionized beam epitaxy at relatively low growth temperature (440°C). During and after the growth, the RHEED pattern of the CaF2 shows single-crystalline nature using this epitaxy technique, whereas polycrystalline CaF2 is grown without ionization and acceleration at the same temperature level. In the high-temperature range (>600°C), although single-crystalline CaF2 is obtained without acceleration, RHEED oscillation is not observed during the growth.