Nanomechanical properties of Bi2Te3 thin films by nanoindentation

Abstract In this study, the microstructural, morphological and nanomechanical properties of Bi 2 Te 3 thin films are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nanoindentation techniques. The Bi 2 Te 3 thin films were deposited on c -plane sapphire substrates using pulsed laser deposition (PLD) under the various helium gas pressures. The XRD results indicated that the Bi 2 Te 3 thin films are textured with the c -axis preferentially oriented normal to the films surface. Both the grain size and surface roughness of the Bi 2 Te 3 thin films exhibit an increasing trend with increasing the helium gas pressure. Furthermore, the hardness and Young’s modulus of the Bi 2 Te 3 thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode were found to range from 2.92 ± 0.12 to 4.02 ± 0.14 GPa and from 106.31 ± 0.63 to 127.46 ± 9.21 GPa, respectively, when the helium gas pressure was increased from 2 × 10 −5 to 2 × 10 −3  Torr.