Twinned InSb molecular layer on Si(1 1 1) substrate

We studied the formation of a twinned InSb molecular layer on Si(1 1 1) substrate (epitaxial relation InSb[1 1 2]∥Si[1 1 0]) by depositing 1-ML Sb on Si(1 1 1)-In(4 × 1) reconstruction at 210°C, using reflection high-energy electron diffraction, X-ray photoelectron spectroscopy and Auger electron spectroscopy. Sb adsorption replaces Si-In bonds in the In(4 × 1) reconstruction and forms Si-Sb bonds. Codeposition of In and Sb on the Si(1 1 1)-7 × 7 surface results in the formation of an InSb film with no twin (epitaxial relation InSb[1 1 0]∥Si[1 1 0]). Annealing this twinned InSb layer above 350°C resulted in the formation of Si(1 1 1)-Sb(√3 × √3) structure, and the coalescence of most of the In. However, direct Sb deposition on Si(1 1 1)-7 × 7 at 350°C results in only disordered phase. Softening of the Si/Sb interface by the Si-In and In-Sb reactions is proposed to be responsible for the formation of the InSb twinned layer (at 210°C) and √3 × √3 structure by Sb (at 350°C).