GaN Schottky barrier diodes (SBDs) with low turn-on voltage are developed for microwave rectification. The diodes with reactively-sputtered TiN electrodes have a lower turn-on voltage compared with the diodes with Ni electrode, while the on-resistance, the reverse leakage current, and the reverse breakdown characteristics are comparable to each other. Theoretically, the SBDs with TiN electrodes can enhance the efficiency of a rectenna circuit at 2.45 GHz from 84% to 89% when the turn-on voltage decreases from 1.0 to 0.5 V.

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 °C-200 °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-μm-diameter device at current of 20 mA, taking into account the series resistance. In the subthreshold region, the forward current (ID) 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 (Ir) versus temperature can be also used for sensor applications.