Soft X-ray photoelectron spectroscopy has been applied to compare the
effect of two S-passivating etchants (S2Cl2 and (NH4)(2)S-x) on the (0
01) surfaces of GaAs and InP. Detailed analysis of substrate and adsor
bate core level emission peaks reveal the similar nature of S-III-V bo
nding in each case. Prior to in-situ annealing, the semiconductor surf
ace is covered by an amorphous layer, and above around 400 degrees C,
a stable S-terminated surface is obtained in each case. Variations in
the relative intensities of spectral features are more sensitive to pr
ocess and temperature differences than to the etchants used. For S-ter
minated GaAs and InP surfaces, a high binding energy component is obse
rved in the substrate Ga 3d and In 4d core level emission spectra corr
esponding to surface S-Ga(In) bonding. The S 2p core level spectra con
tain two components related to the surface and sub-surface S atoms. As
-S bonding on the annealed GaAs-S surface is not present above 400 deg
rees C. (C) 1998 Elsevier Science B.V.