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The temperature dependence of the energy gaps for sulfur-annealed copper indium disulfide has been studied by photorefiectance in the temperature range of 10-300 K. The sulfurannealed sample has been found to have larger transition energies, smaner positive temperature coefficients of energy gaps, and larger spin-orbit splitting energy than the as-grown sample. This can be explained by the reduction of d-level contributions in the upper valence band probably caused by the variation of lattice distance due to native defects.

The adsorption and thermal reaction of H 2 S on the InP(100) surface is studied by synchrotron radiation (SR) soft X-ray photoelectron spectroscopy. In addition to molecular adsorption, H 2 S decomposes to form the dissociative species of S, HS, and H on the surface at 100 K. The S atom of the sulfide species preferentially bonds to the In atom, and the H atom generated by the H 2 S dissociation bonds to the P atom. H 2 S molecules may physisorb on the surface in the form of an icelike multilayer/cluster at low temperatures, even at low coverages. The irradiation of SR white light can induce an alternative reaction of H 2 S with the InP surface to form a thicker sulfur layer than that obtained by thermal deposition. The resulting sulfur layer may provide chemical protection for the InP substrate from further reaction.

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