AlGaN/GaN Schottky Barrier Diode on Si Substrate Employing NiO_x/Ni/Au Contact

Abstract

We proposed and fabricated an AlGaN/GaN lateral Schottky barrier diode (SBD) employing nickel oxide (NiO x )-based double metal contacts, which showed a highly stable reverse blocking capability, by improving the reliability in the high-temperature reverse bias condition. The leakage current of the proposed device was decreased by three orders of magnitude. The measured leakage current of the diode, fabricated using a NiO x (oxidized at 500 °C)–Ni/Au contact as an anode was 236 pA at room temperature while that of the conventional diode was 2.6 µA. The barrier height of the proposed device measured at 200 °C was 0.84 eV while that of conventional one was 0.69 eV. We have also obtained a high breakdown voltage of 1200 V without any additional structure to mitigate the field concentrated at the anode. The highly rectifying contact of the proposed device was attributed to the increment in the barrier height owing to a stoichiometric change at the surface of the device.

High-Voltage AlGaN/GaN High-Electron-Mobility Transistors Using Thermal Oxidation for NiOxPassivation

“…In an effort to address these surface problems, various passivation methods [6][7][8][9] and surface treatments [9][10][11][12] have been studied. Si 3 N 4 passivation [6,7] has widely used to suppress the RF dispersion in microwave applications.…”

“…SiO 2 passivation [8,9] reportedly improves the blocking characteristics of high-voltage switches. Post-annealing [10] or oxidation [11] methods have also been proposed to improve the breakdown voltage and gate leakage current. NiO x has been studied as a p-type ohmic contact in GaN light-emitting diodes [12].…”

“…It has also been reported that NiO x can be used in the gate of normally-off AlGaN/GaN high-electron-mobility transistors (HEMTs) [13] and MOS-HEMTs [14]. The authors successfully suppressed the leakage current of GaN Schottky barrier diodes via oxidation during the fabrication process [11].…”