Temperature sensitivity of SOI-CMOS transistors for use in uncooled thermal sensing

The temperature coefficient of current (TCC) of CMOS transistors implemented on silicon-on-insulator substrates is theoretically and empirically studied for its potential use in uncooled thermal sensing. Modeling and measurements show TCC values in subthreshold of more than 6%/K, better than state of the art microbolometer temperature coefficient of resistance, and less than -0.4%/K in saturation-comparable with metals. Models and measurements are shown for the TCC dependence upon operating point, temperature and channel length. A simple semi-empirical model for the TCC at subthreshold based on long channel approximation is suggested and shown to agree with measurements for channel length down to 0.35 μm. The model and measurements show a logarithmic tradeoff between subthreshold current and the TCC, which is important in the design of sensors.