Application of hydrogenation to low-temperature cleaning of the Si(001)   surface in the processes of molecular-beam epitaxy: Investigation by STM,   RHEED and HRTEM
  Structural properties of the clean Si(001) surface obtained as a result of low-temperature (470--650C) pre-growth annealings of silicon wafers in a molecular-beam epitaxy chamber have been investigated. To decrease the cleaning temperature, a silicon surface was hydrogenated in the process of a preliminary chemical treatment in HF and NH_4F aqueous solutions. It has been shown that smooth surfaces composed by wide terraces separated by monoatomic steps can be obtained by dehydrogenation at the temperatures > 600C, whereas clean surfaces obtained at the temperatures < 600C are rough. It has been found that there exists a dependence of structural properties of clean surfaces on the temperature of hydrogen thermal desorption and the process of the preliminary chemical treatment. The frequency of detachment/attachment of Si dimers from/to the steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration across steps have been found to be the most probable factors determining a degree of the resultant surface roughness. 
L. V. Arapkina, L. A. Krylova, K. V. Chizh, V. A. Chapnin, O. V.   Uvarov, and V. A. Yuryev
cond-mat.mtrl-sci