The top images depict the polishing procedure. From left to right: a) the sample is glued on a sample holder that is then attached to the MULTIPREP TM polishing system; b) after polishing, a clear demarcation (see red arrows) of the exposed interface between Ge and GaInP can be seen; on the left side of the interface an accumulation of matter can be distinguished; c) with an optical microscope, the tapered geometry can be observed on top and it is sketched on the bottom, the yellow dots are guides to the eye showing a small TCS angle, i.e. the angle between the TCS and the bottom of the sample. The bottom images depict the GaAs|GaInP interface that has been observed by SEM (d) and for which EDX (e) measurements were performed on each side of the interface (red and black crosses indicate the analysis spot).