p-NiO/n-GaN Heterostructure Diode for Temperature Sensor Application

p-NiO/n-GaN heterostructure diodes with different anode diameters were fabricated and comprehensively characterized for temperature sensor application. The circular diodes with NiO anode presented good stability in the temperature range from 25 to 200 °C. It is found that the temperature sensitivity is significantly influenced by the series resistance and ideality factor at the fully-turn-on state. A sensitivity of 2.58 mV/K was achieved for the device with a diameter of 100 μm (at 20 mA) and the sensitivity decreased with the increasing area. In the sub-threshold region, the forward voltage at a current density also varied linearly with temperature. The sensitivity-shows high dependence on the forward current density and a smaller current density is corresponding to a higher sensitivity.