Pulsed laser deposition of TiNi thin films at various temperatures

Abstract

Thin films of TiNi shape memory alloy (SMA) have been prepared by pulsed-laser deposition (PLD) at various substrate temperatures. X-ray photoelectron spectroscopy (XPS), surface profile measurements, and X-ray diffraction (XRD) are used to characterize the deposited films. The stoichiometry, deposition rate, and crystallinity of the films are investigated as functions of the substrate temperature. The deposition rates are of the order of 10-2 nm per pulse. The Ni content ranges from 46.7 to 52.0 at.%. It is found that the film deposited at a substrate temperature of 600°C has a polycrystalline structure and austenite is the major phase. It can be concluded that substrate temperature plays an important role in the composition control and the crystallization of the films. The martensitic transformation temperature of the annealed Ti-51.5 at.% Ni thin film is determined to be -20.8°C by differential scanning calorimetry (DSC).