Electron beam evaporated tin oxide thin films for thermistor applications

Abstract

Tin oxide (SnO2) has been extensively used as a gas sensor and transparent conductive oxide owing to its excellent electrical and thermal properties. In this study, the thermal response of SnO2 based thin films has been investigated for negative-temperature-coefficient (NTC) thermistor applications. SnO2 nanopowder has been synthesized through co-precipitation method and subsequently used for depositing thin films via electron beam deposition technique. Eventually, the phase identification of the prepared thin films has been performed with the X-ray diffraction and Raman spectroscopic technique. Excitation and emission studies revealed the presence of defects in the films. Ultimately, temperature dependence properties have been studied in the range of 28–200 °C. The results confirmed the rutile structure of nanocrystalline thin films with grain size less than 8 nm. Further, the resistance of the samples turned out to be strongly dependent on the temperature showing typical NTC characteristics. High-temperature coefficient of resistance (TCR) equivalent to – 38.59 × 10−3 (°C)−1 has been obtained in the temperature range 28–44 °C, which makes the sensor competent for real-time human body temperature monitoring.