MOLECULAR APPROACH TO SURFACE CONTROL OF CHALCOGENIDE SEMICONDUCTORS

The interaction between a chalcogenide semiconductor surface and a spe cific chelating ligand was studied by a number of complementary spectr oscopic methods (UV/VIS, FTIR, XPS). FTIR suggests that the chelating ligand (diphenyl hydroxamic acid) complexes an In3+ ion in CuInSe2, an d a Cd2+ ion in CdTe, accompanied by the loss of a proton. Contact pot ential measurements showed that the adsorbed ligand changes the semico nductor electron affinity without significantly influencing the band b ending. On the basis of these and other results, we suggest that the m olecular dipole of the chelating ligand is responsible for the change in surface potential. Because this dipole can be modified without chan ging the ligand's binding group, this finding opens the way to control surface potential by varying the dipole moment of the adsorbed ligand without changing the binding functional group.