Metal-nitride dual-anode AlGaN/GaN heterostructure Schottky barrier diodes with tunable turn-on voltage and reverse leakage current

Abstract

AlGaN/GaN heterostructure lateral Schottky barrier diodes (SBDs) with TiN and NiN dual anode (DA) on sapphire substrates are investigated in this letter. The NiN anode with its high work-function leads to low leakage current and high breakdown voltage, while TiN anode with its low work-function determines the low turn-on voltage of the DA SBDs. Tunable turn-on voltage and leakage current are obtained in the DA SBDs by varying the radius of the TiN anode. As the radius of the TiN anode decreases from 80 to 8 μm, the turn-on voltage increases from 0.64 to 0.94 V, while the reverse leakage current decreases from 1 × 10−2 to 1 × 10−4 mA mm−1 at a reverse bias of −10 V and cathode–anode distance of 20 μm. The differential specific on-resistance at 100 mA mm−1 is 4.5 mΩ cm2 and barely changes with various radius of the TiN anode. A high breakdown voltage of 1.49 kV is achieved in the AlGaN/GaN DA SBDs with the radius of 80 μm of the TiN anode, obtaining a power Baliga’s figure of merit of 0.48 GW cm−2 at the cathode–anode distance of 20 μm. Besides, dynamic on-resistance increases less than 15% under pulse voltage bias at −60 V which may account on the good interface between metal nitrides and AlGaN, which is beneficial to the high frequency and high power application.