In this paper, AlN films grown by magnetron sputtering method have been proposed as the gate insulator layer of AlGaN/GaN high-electron-mobility-transistors (HEMTs) to decrease gate leakage current and suppress the interface trap. The effect of the temperature of substrate on the quality of AlN films have been investigated. By inserting the thin AlN film (35 nm) as a gate insulator layer, the on-state resistance of AlGaN/GaN HEMTs decrease from 11.1 Ω·mm to 10.3 Ω·mm @Vg = 0 V, the current collapse decreases from 16.6% to 3.2%, the gate leakage can be reduced from 1.2×10-1 A/mm to 4.4×10-6 A/mm @Vg = 2 V by five orders of magnitude, and the fast interface states disappear and the normal trap density decreases from 0.96-1.3×1013 cm-2eV-1 to 1.3-3.4×1012 cm-2eV-1, proving that magnetron-sputtered AlN is an effective way to improve the performance of GaN HEMTs.
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 at a reverse bias of -10 V and cathode-anode distance of 20 μm. The differential specific on-resistance at 100 mA/mm is 4.5 mΩ·cm2and 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 (BFOM) of 0.48 GW/cm2at 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.
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