Electro-mechanical properties and oxidation behaviour of TiAlNxOy thin films at high temperatures

• The gauge factor of TiAlNxOy thin films was estimated up to 500 °C.
• The temperature coefficient of resistance has been measured up to 600 °C.
• The oxidation behaviour of the thin films has been studied.
• The correlation of resistance and oxidation was investigated.

TiAlNxOy thin films are investigated as possible candidates for high temperature stable strain gauge applications. The thin films are deposited by reactive magnetron sputtering on sapphire and silicon substrates with a thickness of 500 nm and 200 nm, respectively. The gauge factor is measured with a custom built setup up to 500 °C. At 100 °C this electro-mechanical parameter is about 2.5 and the mean value decreases by about 10% when exposed to the maximum temperature level applied in this study. The temperature coefficient of the electrical resistance (TCR) is measured under vacuum conditions. The TCR is negative and with a value of –5.13 × 10−4 K−1 very low compared to +3 × 10−3 K−1 determined at sputter-deposited platinum films. Furthermore, the influence of oxidation effects on the electro-mechanical film properties is investigated.