In Figure , it becomes clear from the intensity contour maps that at least the Ga2p, In3d, and P2p core levels were shifted to lower BE when moving from position 1 to the Ge|GaInP interface. To have a closer look at the BE shifts, first, the Ga2p3/2, In3d5/2, P2p, and Ge3d core level spectra were fitted to discriminate the BE of the GaInP and Ge 0 states from the more oxidized ones. Then, the maxima of the GaInP and Ge 0 states were deduced (see Figures and). Finally, the BE shifts were calculated using reference BE measured for pure Ge (position 1 -29.5 eV) and pure GaInP (position 20 -129.7 eV, 445.3 eV, and 1118.4 eV). The result is shown in Figure . When moving closer to the interface, a shift to lower BE for the Ge3d core level, and a shift to higher BE for the elements composing the n-GaInP are observed.