SURFACE CHARACTERIZATION FOR SPUTTER-CONE FORMATION ON INP(100)

The dynamic processes of sputter-cone formation for the InP surface, w hich occur during the depth profiling of InP/InGaAs multilayers, have been studied by ion scattering spectroscopy (ISS), reflection electron microscopy (REM) and reflection high-energy election diffraction (RHE ED) as a function of sputtering time. Results show preferential sputte ring of phosphorus atoms and the formation of an altered amorphous lay er which is followed by surface roughening as a transition stage to co ne formation. After reaching a steady state, the ISS spectra remain al most the same despite ion sputtering, even though the surface becomes covered with a significant number of cones. RHEED and REM observations revealed that the shank of the cone is composed of crystalline InP, w hich is covered by an altered layer of InP with an In metal ball situa ted on the top of the cone. Monte Carlo simulation has predicted that preferential sputtering of phosphorus causes the InP surface to be In rich, suggesting that the excess In atoms should agglomerate to form t he metallic In ball on the surface. (C) 1998 Published by Elsevier Sci ence B.V. All rights reserved.