For GaInP, oxidation states similar to those previously observed in the case of the Ge|GaInP interface were observed (see Figure ). This is valid for each of the Ga2p, In3d, and P2p core levels with, for instance, the characteristic energy difference of 4.6 eV between the two P states indicating the formation of InPO4 or In(PO3)3 (see Figure ). On position 20 (pure GaInP)