Studies of nanoindentation and residual stress analysis of Ge/GaAs epilayers

The nanomechanical properties of germanium (Ge) epilayers grown at different temperatures by horizontal home-made metal organic vapor phase epitaxy were studied with nanoindentation using Berkovich and Vickers indenters. The surface morphology of the grown samples was studied by means of atomic force microscopy. High resolution x-ray diffraction (HRXRD) measurements were performed for structural analysis. The present investigation is mainly aimed at the understanding of the relation of hardness with the residual stress. The residual stress values obtained from HRXRD studies are compared with the hardness and elastic modulus values determined from nanoindentation analysis. It was found that the nanomechanical properties are correlated with the observed residual stress. The defects induced mechanism due to the change in load on Ge/GaAs epilayers has been elucidated. This kind of study will lead to improvement of Ge/GaAs films with respect to the deposition conditions understood from the variations in the nanomechanical studies.