Journal of Vacuum Science & Technology B, Vol.12, No.4, 2689-2693, 1994
Step Bunching and Step Equalization on Vicinal GaAs(001) Surfaces
Terrace width distributions have been calculated from scanning tunneling microscopy (STM) images of molecular-beam epitaxy (MBE)-grown GaAs(001) surfaces misoriented by both 1-degrees and 2-degrees towards the (111)A direction. This analysis reveals a peak in the terrace width distribution at approximately 40-50 angstrom, regardless of the original miscut, with larger terraces forming in order to preserve the angle of vicinality. Growth of a tilted.superlattice (TSL) improves the periodicity of the surface. A statistical analysis of the STM image of a 1-degrees TSL capped with three monolayers of GaAs reveals a bell-shaped distribution of terrace widths with a peak at the average terrace width. These results suggest that MBE growth of vicinal GaAs(001) does not result in equalized steps but that the growth of a TSL does tend towards step equalization. The differences between these two growth regimes are discussed.
Keywords:MOLECULAR-BEAM EPITAXY;SCANNING-TUNNELING-MICROSCOPY;TERRACE-WIDTH;GAAS-SURFACES;ELECTRON-MICROSCOPY;GROWTH;SUPERLATTICES;SPECTROSCOPY;DEPOSITION;(AL;GA)AS