Evaluation of nanoindentation characteristics of cubic InN epilayer grown by Molecular Beam Epitaxy

Abstract The potential of the III-nitride semiconductor materials for modern optoelectronic applications as diodes, transistors, LEDs, and photovoltaics has prompted the mechanical characterization of small volumes as thin films. In this paper, the load-displacement curves of cubic indium nitride (c-InN) obtained during the nanoindentation with a Berkovich indenter were investigated. c-InN was obtained by plasma-assisted molecular beam epitaxy growth on c-GaN/MgO (100). The thickness of the c-GaN buffer layer used in all the films studied was 350 nm to eliminate the substrate's effect on the material studied properties. The c-InN thickness is around 180 nm. The reflection high energy electron diffraction and the X-ray diffraction results show that the c-GaN buffer and c-InN grown layers had a high cubic zincblende phase with more than 97%. The obtained value of the hardness is 12.5 ± 0.4 GPa, and the value for Young's modulus is 365.6 ± 7 GPa with a Poisson's ratio of 0.3.