Rutherford back-scattering spectroscopy (RBS) was used in combination with X-ray photo-emission spectroscopy (XPS) to investigate Ge diffusion in Al2O3 (00•1) samples. Ge was implanted in c-plane α-Al2O3 (00•1) at 80 keV to a fluence of 1016/cm2 at room temperature followed by thermal annealing in the 30-180min range at 1200C in a N2 environment. RBS results indicate that implantation-induced damage does not fully amorphize the substrate, while incurred defects were partially annealed after 1h accompanied by Ge phase crystallization. XPS data confirms the existence of GeO2 and GeO. There was a decrease in the Ge content compared to the as-implanted sample, attributed to GeO desorption, which was evident after 30min and by 180min 15% of the original Ge concentration remains. Integrated intensity of the Ge peak in aligned geometry was much lower compared to random geometry with a bimodal distribution of Ge evident in both spectra indicating Ge substitutional incorporation and the formation of a distinct Ge layer. XPS data shows a peak thought to be associated with the distinct Ge layer at ≈1216.5eV, which was a lower binding energy than a Ge reference peak. The lower binding energy was thought to result from a net positive electron density in the substrate due to excess Al atoms in the peak defect-region.

Ion Beam Studies of Ge Diffusion in Al2O3. E.G.Barbagiovanni, S.N.Dedyulin, P.J.Simpson, L.V.Goncharova: Nuclear Instruments and Methods in Physics Research B, 2012, 272, 74-7