Reflection High-Energy Electron Diffraction Intensity Oscillations during Si MBE Growth on HF-Treated Si(111) Surface

Reflection high-energy electron diffraction (RHEED) intensity oscillations were observed when Si was directly grown at 450°C on the Si(111) surfaces treated with pH-modified (pH=9-10) buffered HF (BHF) solution without a conventional high-temperature cleaning step in ultrahigh vacuum (UHV). On the other hand, a 5% HF-treated Si(111) surface showed weak RHEED intensity oscillations even if a 800°C, 20 min heat treatment was performed before growth in UHV. These results indicate that the Si(111) surface treated with pH-modified BHF is flat and clean enough for direct Si molecular beam epitaxy (MBE) growth on it.