Quasi-vertical diamond temperature sensor by using Schottky–pn junction structure diode

A Schottky–pn junction structure diode (SPND) has been fabricated on HPHT Ib (001) diamond substrate for temperature sensor application. The forward current-voltage characteristics show an obvious temperature dependency with the turn-on voltages decrease with the increasing temperature. It demonstrates that three types of current transport mechanisms are found at different forward bias voltages. Furthermore, based on the good linear relationship between the turn-on voltages and temperatures, the sensing ability is evaluated at the sub-threshold region. At low current densities (<10−2 A/cm2) high thermal sensitivities are reached (>4.75 mV/K, with a maximum value of 5.31 mV/K at 10−3 A/cm2 of current density) which is remarkably above the sensitivity obtained by other semiconducting material devices. Furthermore, the deviation of sensitivity from the theoretic model is attributed to the relatively higher ideality factor value.