Study of InP Surfaces after Wet Chemical Treatments

The influence of different wet chemical treatments (HCl, H2SO4, NH4OH) on the composition of InP surfaces is studied by using synchrotron radiation photoemission spectroscopy (SRPES). It is shown that a significant amount of oxide remains present after immersion in a NH4OH solution which is ascribed to the insolubility of In3+ at higher pH values. Acidic treatments efficiently remove the native oxide, although components like P0, In0 and P(2±Δ)+ suboxides are observed. Alternatively, the influence of a passivation step in (NH4)2S solution on the surface composition was investigated. The InP surface after immersion into (NH4)2S results in fewer surface components, without detection of P0 and P(2±Δ)+ suboxides. Finally, slight etching of InP surfaces in HCl/H2O2 solution followed by a native oxide removal step, showed no significant effect on the surface composition.