Mechanical properties of InGaN thin films deposited by metal-organic chemical vapor deposition

We report in this study characteristics of InGaN thin films developed by metal-organic chemical vapor deposition (MOCVD) at various growth temperatures. The effect of deposition temperatures on microstructures and mechanical properties are examined using X-ray diffraction (XRD), scanning probe microscopy (SPM), and nanoindentation techniques. The XRD analysis shows no evidence of phase separation for InGaN thin films. The SPM micrographs indicate that the films have relatively smooth surfaces. Hardness and Young's modulus of InGaN thin films vary according to the deposition temperature. As the deposition temperature increases from 730 to 790 °C, the grain size increases from 28 to 52 nm. Hardness for InGaN thin films dropped from 13.8 to 17.6 GPa in accordance with the increase of the grain size. By fitting experimental data with the Hall-Petch equation, a probable lattice friction stress of 3.48 GPa and Hall-Petch constant of 73.15 GPa nm^1/2 are obtained.