Nanoindentation studies of gallium arsenide heteroepitaxial layers

Gallium arsenide epilayers were deposited by horizontal home-made metal organic chemical vapor phase epitaxy, using trimethylgallium and arsine precursors with hydrogen as carrier gas at a pressure of 60 mbar. The samples were grown at a temperature of 600 degrees C over germanium substrates with different III/V ratio. High resolution X-ray diffraction measurements showed good crystalline quality and are not significantly affected by the variations in III/V ratio. Nanomechanical properties of grown samples were studied with nanoindentation using Berkovich and Vickers indenters, hardness and elastic modulus values have been determined. The defects induced phenomena due to the change in load on GaAs/Ge epilayers have been elucidated.