Influence of Boron Adsorption over Si(111) Surface on Si Molecular Beam Epitaxial Growth Studied by Reflection High-Energy Electron Diffraction

Abstract

Epitaxial growth of Si on top of a boron-adsorbed Si(111) surface was studied in a molecular beam epitaxy (MBE) system. When the initial boron coverage was more than 1/3 monolayer (ML), reflection high-energy electron diffraction (RHEED) intensity oscillation showed a 4 ML period in the early stage of Si growth as long as surface-segregated boron at the growing surface was more than 1/3 ML, and turned to the normal 2 ML period of oscillation. Periodical change of the full width at half-maximum (FWHM) of the RHEED specular spot confirmed that this is due to two-dimensional island growth of 4 ML height and the coalescence mode of Si.

Towards controlled molecular beam epitaxial growth of artificially stacked Si: Study of boron adsorption and surface segregation on Si(111)

“…The situation changes for B-adsorbed Si(1 1 1) surfaces. At c B ¼0.5 ML, RHEED intensity oscillations indicate a 2 BL growth mode, as already reported earlier [4,5]. For lower c B , the RHEED intensity oscillations become initially irregular indicating a change in the growth mode [6].…”

“…The surface then only contains Si adatoms without dangling bonds. Si growth on such a van-der-Waals like surface was found to be changed to a two-bilayer (2 BL) growth mode under certain conditions [4][5][6].…”

Role of boron and (√3 × √3)‐B surface defects on the growth mode of Si on Si(111): A photoemission and electron diffraction study

“…The growth behaviour of Si is different for Si(111)‐(7 × 7) and (√3 × √3)R30°‐B, respectively. As reported recently, the growth mode changes from a bilayer (BL) growth towards a layer‐by‐layer growth via the nucleation of Si islands two‐bilayer (2BL) high under certain conditions 3, 4. Moreover, the islands are nucleated in twin position with respect to the substrate resulting in a change of Si epitaxial layer orientation 5–7.…”

“…Already 20 years ago, the occurrence of RHEED intensity oscillations was reported for gas‐source MBE growth of Si on Si(111) accompanied by high boron doping, whereas no oscillations were observed for the growth on Si(001) 16. More detailed investigations demonstrated, that for Si growth between 725 and 800 K on highly boron‐doped Si(111) RHEED intensity oscillations exhibited a 2BL period in the early stage of growth as long as c B was ≥2/3 ML at the surface, and turned to the normal BL period during further growth 3. Only BL oscillation period was observed in the initial stages of Si growth at T > 800 K, even for c B = 1 ML.…”

“…Only some reports about in situ RHEED investigations of Si MBE growth on boron‐covered Si(111) can be found 3, 4, 16. Already 20 years ago, the occurrence of RHEED intensity oscillations was reported for gas‐source MBE growth of Si on Si(111) accompanied by high boron doping, whereas no oscillations were observed for the growth on Si(001) 16.…”