SULFURIZATION OF INP(001) SURFACES STUDIED BY X-RAY PHOTOELECTRON AND X-RAY-INDUCED AUGER-ELECTRON SPECTROSCOPIES (XPS/XAES)

Surface chemistry of n- and p-doped InP(001) after treatment with sulfur from different sources has been investigated by XPS/XAES measurements. Core level lines, valence band spectra and Auger transitions were related to changes in surface chemistry and band bending. Both high resolution chemical shifts and the Auger parameter concept were used for the identification of chemical species. Sulfurization was performed by dipping the chemically cleaned sample into a (NH4)(2)S solution or by exposing it to S-2 or H2S molecules in UHV. Depending on the source and on the annealing temperature several sulfur compounds were observed on the surface and identified as sulfides with sulfur substituting phosphorus or with sulfur as surface atom, and as polysulfide probably with one sulfur atom in a terminal position. Changes of surface Fermi energy position and thus band bending were investigated.