Surfactant Mediated Layer by Layer Growth of a Liquid Metal on a Si(111) Surface

Abstract

Morphology and atomic structure of Ga films grown on Si(111)-7×7 and -√7×√3-In surfaces at room temperature were studied by using scanning tunneling microscopy and reflection high-energy electron diffraction (RHEED). Ga grew into liquid droplets on the Si(111)-7×7 surface, as it does on many other semiconductors. On the other hand, on the √7×√3-In surface, Ga grew into an ordered flat film and In floated to the uppermost layer. In this growth, resultant Ga films were very flat in a wide range of Ga coverage from 0.17 to 50 monolayers, and the top layer had various periodicities such as √3×√3, √3/2×√3/2 and 5×5 periodicities depending on Ga coverage. Layer-by-layer growth of Ga on semiconductor surfaces is a quite unusual phenomenon. Such flat Ga films would be useful to fabricate high-quality nano films of GaAs and GaN on Si surfaces by exposing these films to As₄ and NH₃