RHEED intensity oscillations of mbe grown Ge/Si ultra-thin multi-layered structures

Abstract

The behavior of RHEED intensity oscillations during molecular beam epitaxy of Ge/Si ultra-thin multi-layers on Si(100) and Si(111) substrates has been studied. During the growth of alternating Ge and Si layers on a Si(100) substrate, a single atomic layer mode RHEED intensity oscillation is observed along either 〈011̄〉 or 〈010〉 azimuthal direction. The RHEED intensity oscillations for continuously growing Ge on Si(100) could last up to 6 periods, which correspond roughly to the critical thickness of pseudomorphic growth of Ge on Si. The RHEED intensity oscillations for growing Ge and Ge/Si multi-layers on Si(111) seem more complicated than that on Si(100). Along the 〈011̄〉 azimuth, the RHEED intensity oscillations show a non-uniform periodicity, which is caused by a change in surface reconstructions. The phase-locked behavior and the intensity recovery of RHEED oscillations after growth interruption have been observed, which reveal the different surface diffusion constants of Ge and Si atoms on Si(100) and Si(111).