Giant Temperature Coefficient of Resistance in ZnO/Si (111) Thin Films

Giant negative temperature coefficient of resistance (TCR) was observed in ZnO/Si (111) thin films. The films were grown using the pulsed laser deposition (PLD) technique, taking Si (111) wafer as substrates, with a substrate at the temperature below 450°C in the PLD. It is found that both TCR-temperature behavior and TCR value are strongly affected by deposition temperature. The maximal TCR value over -10.9%K^-1 can be observed at the deposition temperature from 20°C to 350°C and reaches to -13%K^-1 at deposition temperature 20°C where the film shows X-ray diffraction amorphous. The results suggest that the ZnO/Si films demonstrate great potentials when used in a low-cost, high-performance, non-cooling and highly sensitive bolometer.