X-ray standing wave study of wet-etch sulphur-treated InP 100/ surfaces

Normal incidence X-ray standing wave NIXSW.measurements are presented for sulphur terminated InP 100.surfaces, prepared by wet-etch in NH4.2S solution followed by UHV anneal. Standing wave profiles for sulphur 1s photoyield in three planes 220, 311 and 311.indicate that sulphur is close to the phosphorus site. Coherent positions and fractions are compared with the predictions of a number of models of the surface, including novel 2=2 structures. The experimental data can be reproduced by a general two-dimer model, but it is more likely that the data are reflecting significant disorder. q2000 Elsevier Science B.V. All rights reserved