Influence of the sputter gas composition on the electromechanical properties and on the stability of TiAlNxO1-x thin films

Sputter deposited TiAlNxO1-x thin films are investigated as potential candidates for high temperature strain gauge applications. In this study the influence of the reactive gas atmosphere during deposition on the electromechanical properties is investigated up to 500 °C with a custom-built measurement setup enabling gauge factor determination. It is shown, that TiAlNxO1-x thin films with no oxygen admixture during the deposition process show the most promising electromechanical properties. The gauge factor decreases from 3.3 to 2.4 between room temperature and 500 °C, while in this temperature range the linear temperature coefficient of the electrical resistance has a value of −3.8·10−4 K−1. Time-of-flight secondary mass ion spectrometry measurements are evaluated against the results of electrical resistance measurements to estimate the growth of an oxide layer on the surface of the TiAlNxO1-x thin films when operated at 500 °C in air.