Study on novel temperature sensor based on amorphous carbon film

In this study, a new type of thermistor temperature sensor was developed. The sensing materials was amorphous carbon (a-C) film prepared using electron cyclotron resonance (ECR) plasma processing system under low energy electron irradiation sputtering. The nanostructure of a-C film was observed by transmission electron microscope (TEM), the atomic bonding and carbon hybridisation condition was analysed by Raman spectra and X-ray photoelectron spectroscopy (XPS), respectively. The linearity of temperature-resistance curve of this kind of a-C film was very good in certain temperature range, with high temperature coefficient of resistance (TCR). The a-C film by 50 eV electron irradiation can measure larger temperature range from –75°C to 155°C, with good repeatability. The working temperature range of a-C film by 100 eV electron irradiation was much smaller, but TCR absolute value of this film was higher. It can be concluded that the lower sp2/sp3, the better linearity of temperature-resistance curve, the lower TCR absolute value in certain working temperature range. The research shows that this kind of a-C film temperature sensor has good linearity and repeatability; also it can be integrated with other MEMS sensor simply.