Reconstructions upon thermal desorption in ultra high vacuum of InSe covered Si(111) surfaces

Abstract

At an InSe/Si(111) heterostructure, the transition between the cubic Si substrate and the layered compound InSe remains a problem. The surface structure of InSe films grown by molecular beam epitaxy on Si(111) substrates has been studied under ultra high vacuum by low energy electron diffraction, Auger electron spectroscopy, and helium atom scattering upon sequential thermal erosion of the film until full removal. Between the initial 1 × 1 diagram of InSe(001) and the In-induced √3 × √3 R 30° pattern of Si(111), two intermediate stages were observed. One, above the single layer coverage range, corresponds to the coexistence, over a strained bonding half-layer, of InSe layers strained to the Si parameter and of others which are relaxed to bulk InSe parameter. The second stage, below the half-layer coverage range, is characterized by a nearly 5 × 5 mesh of Si(111) which could arise from two-dimensional islands made of both In and Se.