  We investigate thin film resistive thermometry based on
metal-to-insulator-transition (niobium nitride) materials down to very low
temperature. The variation of the NbN thermometer resistance have been
calibrated versus temperature and magnetic field. High sensitivity in
tempertaure variation detection is demonstrated through efficient temperature
coefficient of resistance. The nitrogen content of the niobium nitride thin
films can be tuned to adjust the optimal working temperature range. In the
present experiment, we show the versatility of the NbN thin film technology
through applications in very different low temperature use-cases. We
demonstrate that thin film resistive thermometry can be extended to
temperatures below 30 mK with low electrical impedance.
