Fabrication of High Quality Ni1-xPtx Films for Use as Materials in High-Sensitivity Temperature Sensor

High-quality thin films of Ni1-xPtx alloys have been investigated as materials for temperature sensors with a high temperature coefficient of resistance (TCR). Since the high TCR of Ni has been attributed to the spin-disordered scattering occuring just below the Curie temperature (TC), we considered that a higher TCR can be obtained by decreasing TC to be slightly greater than room temperature (RT) by alloying Ni with Pt. Ni1-xPtx alloy films have been prepared on different substrates by RF magnetron sputtering followed by annealing in high vacuum. TCRs as high as 10000 ppm/K at RT were obtained in the case of the Ni0.75Pt0.25 alloy film prepared on a SrTiO3 (STO) substrate. This TCR is 2.5 times higher than that of commonly available Pt temperature sensors.