XPS investigation of oxide films on InP(100)

Abstract The effect of chemical etching and the oxide growth on the etched surfaces on n‐ and p‐InP(100) have been studied using X‐ray photoelectron spectroscopy. The samples were etched in HCI (1 molar in methanol) and then annealed at 650 K in a vacuum for 1 hour. After this procedure both samples were oxidized in air at room temperature for a long time. The stoichiometry of the oxide layer was determined by angle‐resolved analysis of core level spectra. The surface treatment leads to an indium‐rich surface. After annealing the In/P atomic ratios amount to 2.0 and 1.5 for n‐InP and p‐InP, respectively. Most of the oxygen on the surface after etching and annealing is presented as In 2 O 3 and In(OH) 3 . Within the oxide layers of the air‐oxidized samples the In/P atomic ratios vary from 2.5 to 3.7 for both n‐ and p‐InP showing a depletion of P during the oxidation. From angle‐dependent measurements it is concluded that the oxide layers consist of InPO 4 and In(OH) 3 whereas the outer layer is InPO 4 ‐rich. The presence of In 2 O 3 can be suggested in the oxide layer of n‐InP only. The oxidized p‐type sample contains more oxygen than the n‐type one.