SULFIDE PASSIVATION OF III-V SEMICONDUCTOR SURFACES - ROLE OF THE SULFUR IONIC CHARGE AND OF THE REACTION POTENTIAL OF THE SOLUTION

A model is proposed for describing the effect of a solution on the ele ctronic properties of sulfided surfaces of III-V semiconductors which treats the adsorption of sulfur in terms of a Lewis oxide-base interac tion. According to this model, the density of states on a sulfided sur face, which pin the Fermi level, decreases as the global hardness of t he electron shell of the adsorbed sulfide ions is increased. The Thoma s-Fermi-Dirac method is used to calculate the global hardness of sulfi de ions with different charges as a function of the dielectric constan t of the medium. It is shown that the hardness of a sulfur ion is grea ter when its charge is lower and the dielectric constant of the solven t is lower. (C) 1998 American Institute of Physics. [S1063-7842(98)020 08 -X].