CrO x N y Thin Film Temperature Sensors for High-Precision Cryogenic Measurement in Strong Magnetic Field

Cryogenic temperature measurement in strong magnetic field is indispensable for researches based on cryogenic and strong magnetic field composite environment. In this work, oxygen is added into CrNx film to form CrOxNy for the development of resistive cryogenic temperature sensor with high sensitivity, high stability and low magnetoresistance. CrOxNy thin films with different electric properties were deposited under variant N2/O2 gas flow rates by DC magnetron reactive sputtering, and micro sensors were fabricated. The sensors’ performances were systematically analyzed in 4.2K~300K. They show super-high sensitivities, the absolute sensitivity is between 2.61 and 4.26 when the N2/O2 flow rate is 17.8sccm. The temperature measurement shift after 10 and 15 thermal cycles between 4.2K ~ 300K is in the range of −8.26mK ~ 11.79mK. The temperature measurement shift in magnetic field of 9T is in the range of −30.2mK~178mK, and the relative deviation is in the range of ±0.164%, with an absolute value of less than 0.086% at most of the measured points, indicating strong performance of against the influence of magnetic field.