Effect of ammonium-sulfide solvent on the surface passivation of GaSb (100)

X-ray photoemission spectroscopy and scanning electron microscopy are used to study the effect of a solvent on the chemical composition of a sulfide passivating layer formed on GaSb (100) surface. Treatment of the GaSb (100) surface with ammonium-sulfide solutions results in the formation of a thick (several tens of nanometers) coating composed of a mixture of various binary and ternary gallium and antimony sulfides. The chemical compositions of the passivating sulfide layers formed in aqueous and alcoholic ammonium-sulfide solutions are different. Annealing of the sulfide layer at 360$^\circ$C in ultrahigh vacuum leads to the partial desorption of antimony from the surface, the decomposition of ternary sulfides into their binary constituents, and change in the surface band bending of this layer.