Chemical modification of the GaP(001) surface electric field with sulfide solutions

The surface electric field in GaP(0 0 1) passivated with aqueous and alcoholic sulfide solutions is studied by reflectance anisotropy spectroscopy using data on the surface chemical and electronic structure obtained by synchrotron-radiation X-ray photoelectron spectroscopy. Treatment of n-GaP(0 0 1) surface with a sulfide solution decreases the surface electric field depending on sulfide solution composition. In particular, passivation with the solution of ammonium sulfide in 2-propyl alcohol turns the total surface electric field almost to zero, while passivation with the aqueous ammonium sulfide solution reduces the surface electric field in a lesser extent. On the other hand, sulfide treatment of p-GaP(0 0 1) surface enhances the surface electric field dramatically and this enhancement is nearly independent of the sulfide solution composition. Such changes in the surface electric field can be related to the modification of the dipole associated with chemical bonds in the passivating layer.

Automated summary

The study investigates the surface electric field changes in GaP(0 0 1) treated with aqueous and alcoholic sulfide solutions using reflectance anisotropy spectroscopy and synchrotron-radiation X-ray photoelectron spectroscopy. Treatment with a sulfide solution reduces the surface electric field on the n-GaP(0 0 1) surface, with the degree of reduction depending on the composition of the sulfide solution. Passivation with ammonium sulfide in 2-propyl alcohol almost eliminates the total surface electric field, while passivation with aqueous ammonium sulfide solution shows a lesser reduction. Conversely, sulfide treatment of the p-GaP(0 0 1) surface dramatically enhances the surface electric field, regardless of the sulfide solution composition. These changes in the surface electric field are likely associated with the modification of dipole moments in the passivating layer.