Enhanced thermal constant B of diamond films for ultrahigh sensitivity negative temperature coefficient thermistors

Abstract

Negative temperature coefficient (NTC) thermistor plays a crucial role in science research and engineering applications for precise temperature monitoring. Although great progress has been achieved in NTC materials, enhancing sensitivity and maintaining this high sensitivity along with linearity across extensive temperature ranges remain a significant challenge. In this study, we introduce a diamond-based thermistor (DT) characterized by its outstanding sensitivity, swift response time, and broad temperature monitoring capabilities. The temperature constant B for this DT, measured from 30 to 300°C (B_30/300), achieves an exceptional value of 8012 K, which notably exceeds the temperature sensing capabilities of previously reported NTC thermistors within this extensive range. Moreover, diamond’s unique thermal conductivity and stability significantly boost the response speed and durability of the DT, offering substantial advantages over traditional ceramic thermistors. The enhanced temperature-sensitive properties of the DT are attributed to the presence of impurity elements in polycrystalline diamond. Impedance analysis indicates a hopping conduction mechanism, likely involving C-H or C-N dipoles at the diamond grain boundaries. This study marks a significant leap forward in diamond thermistor technology and sheds light on the mechanisms of thermal active conduction in diamond materials.