Epitaxial 4H–SiC based Schottky diode temperature sensors in ultra-low current range

Abstract

This work reports highly sensitive and linear temperature sensors based on epitaxial silicon carbide (SiC). Circular shaped Ni/4H-nSiC Schottky barrier diode (SBD) temperature sensors of area 3.140 mm2 have been fabricated and characterized in forward current (If) and temperature range from 10 pA to 5 nA and 233 K–473 K, respectively. The highest value of absolute thermal sensitivity |S| has been achieved as 3.425 mV/K at the lowest If = 10 pA. The sensors show best performance at If = 0.1 nA with lowest root mean square error, temperature error and highest coefficient of determination as 5.341 mV, 1.620 K and 99.96%, respectively, with |S| = 3.295 mV/K. Moreover, for If ≤ 20 pA, sensors reach their maximum operating temperature point, i.e., 448 K. The highest value of self-heating in the sensors have been calculated as 1.623 nK. Moreover, asymmetry has been observed between experimental and the theoretical values of |S| which are explained using variation in the barrier height patches (probably caused by defects at the interface) parameter like their effective area, radius, number, barrier height at the saddle point, with the temperature.