Nanomechanical and wettability properties of Bi2Te3 thin films: Effects of post-annealing

In this study, Bi2Te3 thin films were deposited on SiO2/Si(100) substrates by pulsed laser deposition (PLD) at 250 °C. The films were then annealed in-situ in the deposition chamber at various annealing temperatures (Ta ) ranging from 200 to 300 °C. The microstructural, morphological, and nanomechanical properties of the Bi2Te3 thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy, and nanoindentation techniques, respectively. The XRD results indicated that all the Bi2Te3 thin films have high crystalline quality with predominant (0015) texture. Nano-indentation measurements performed with a Berkovich nanoindenter operating under the continuous contact stiffness measurement mode revealed that both the hardness and Young's modulus of the Bi2Te3 films decreased with increasing Ta . In addition, the water contact angle measurements were carried out to delineate the effects of annealing on the changes in the surface energy and wettability of the films.