THE GASE SI(111) INTERFACE - A CORE-LEVEL STUDY/

A heterostructure, prepared by molecular beam deposition, of the layer ed compound GaSe onto Si(111)1 x 1-H has been characterised by ultravi olet photoelectron spectroscopy upon sequential thermal erosion in ult rahigh vacuum. In the temperature range investigated (370-570 degrees C), several steps were observed in the evolution of the Ga 3d and Se 3 d core level spectra, from the initial GaSe compound to the Si(111)roo t 3 x root 3-Ga surface. Decomposition of the core level spectra was u sed to identify the different contributions of the system. The Ga as w ell as the Se atoms of the layered compound are in one chemical enviro nment. 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 Ga Se layer bonded to Si. (C) 1998 Elsevier Science B.V.