Estimation of indium-to-germanium and gallium-to-germanium sputtering yield ratios using cosputtering deposition

Abstract

The relative concentration of In and Ga atoms incorporated to hydrogenated amorphous germanium (a-Ge:H) films by the cosputtering of solid In and Ga sources together with a crystalline Ge target in a H-containing Ar plasma has been measured by means of Rutherford backscattering spectrometry and particle-induced x-ray emission. Both the experimental In-to-Ge and Ga-to-Ge relative concentrations were found to linearly scale with the respective In/Ge and Ga/Ge sputtered area ratios. From the slopes of these linear dependencies, In-to-Ge and Ga-to-Ge sputtering yield ratios were estimated. The results were found to be consistent with published theoretical sputtering yield values, but to disagree with experimental sputtering yield results previously reported for the case of the In-to-Ge yield ratio. For the case of Ga, a sputtering yield value of 1.6 atoms/ion was deduced from the present results, which gives first experimental account of Ga sputtering by Ar ions.