Study of InP Surfaces after Wet Chemical Treatments

The influence of different wet chemical treatments (HCl, H 2 SO 4 , NH 4 OH) 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 NH 4 OH solution which is ascribed to the insolubility of In 3+ at higher pH values. Acidic treatments efficiently remove the native oxide, although components like P 0 , In 0 and P (2±Δ)+ suboxides are observed. Alternatively, the influence of a passivation step in (NH 4 ) 2 S solution on the surface composition was investigated. The InP surface after immersion into (NH 4 ) 2 S results in fewer surface components, without detection of P 0 and P (2±Δ)+ suboxides. Finally, slight etching of InP surfaces in HCl/H 2 O 2 solution followed by a native oxide removal step, showed no significant effect on the surface composition.