Correlation Between Anode Area and Sensitivity for the TiN/GaN Schottky Barrier Diode Temperature Sensor

TiN/GaN Schottky barrier diodes with different anode diameters are fabricated to investigate the temperature sensing mechanism. All the circular diodes present good stability over a temperature range of 25 degrees C-200 degrees C. In the fully turn-on region, the sensitivity increases with the increasing diameter. Furthermore, the highest sensitivity of 1.22 mV/K is obtained for a 300-mu m-diameter device at current of 20 mA, taking into account the series resistance. In the subthreshold region, the forward current (I-D) density determines the sensor sensitivity, in which a larger current density corresponds to a lower sensitivity. In addition, the strong dependence of the leakage current on the temperature indicates that the linearity of ln (I-r) versus temperature can be also used for sensor applications.