Nanoindentation responses of InN thin films

In the present study, the structural and nanomechanical characteristics of InN thin films are investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The InN thin films were deposited on the GaN/(0 0 0 1) sapphire substrates by using the metal-organic chemical-vapor deposition (MOCVD) system. The XRD results indicated that InN thin films are pure hexagonal phase with the (0 0 2)-oriented characteristics. The “pop-ins” phenomena observed in the load-displacement curve during loading are due primarily to the activities of dislocation nucleation and propagation. Based on this scenario, an energetic estimation of dislocation nucleation is made. In addition, the hardness and Young's modulus of InN thin film are obtained by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. The obtained values of the hardness and Young's modulus are 4.2 ± 0.1 GPa and 152.5 ± 3.9 GPa, respectively.