The GaSe/Si(111) interface: a core level study

A heterostructure, prepared by molecular beam deposition, of the layered compound GaSe onto Si(111)1 x 1-H has been characterised by ultraviolet photoelectron spectroscopy upon sequential thermal erosion in ultrahigh vacuum. In the temperature range investigated (370-570 degrees C), several steps were observed in the evolution of the Ga 3d and Se 3d core level spectra, from the initial GaSe compound to the Si(111)root 3 x root 3-Ga surface. Decomposition of the core level spectra was used to identify the different contributions of the system. The Ga as well as the Se atoms of the layered compound are in one chemical environment. The contribution of strained GaSe layers that have the lattice parameter of the Si substrate is found before the appearance of Si 2p. The GaSe/Si(111) interface is described by only one contribution and the result is correlated to the structural model of half a strained GaSe layer bonded to Si. (C) 1998 Elsevier Science B.V.