Low Turn-On Voltage and Reverse Leakage Current β -Ga₂O₃ MIS Schottky Barrier Diodes With an AlN Interfacial Layer

We demonstrate for the first time a vertical metal/AlN/β-gallium oxide (β-Ga2O3) metal-insulator–semiconductor (MIS) Schottky barrier diode (SBD) with low turn-on voltage (Vₒₙ) and reverse leakage current. By employing an ultrathin AlN layer enabled by atomic layer deposition (ALD), the resulting AlN/β-Ga2O3 MIS SBD exhibits a remarkably low leakage current of0.1~μA/cm2, which is three orders of magnitude smaller than that of the conventionalβ-Ga2O3 SBD. Meanwhile, the AlN/β-Ga2O3 MIS SBD shows a significantly improved breakdown voltage from 208 V up to 890 V, while maintaining a relatively lowVₒₙof 0.92 V andon-resistance (Rₒₙ) of 11.8 mΩ ·cm2, respectively. I–V measurements conducted across a range of temperatures from 298 to 432 K indicate that thermionic field emission (TFE) and trap-assisted tunneling (TAT) are the predominant electron transport mechanisms under forward bias if inserting 2 nm AlN, while TFE becomes dominant mechanism when the AlN thickness increases up to 5 nm. X-ray photoelectron spectroscopy (XPS) characterizations reveal the type I alignment for AlN/β-Ga2O3 heterojunction with a large conduction band offset (Δ EC) of 1 eV, which could function as an electron transport barrier under reverse conditions, thereby greatly suppressing the leakage current. Our study for the first time suggests a great potential for ALD-derived AlN films to be an interfacial layer inβ-Ga2O3 SBDs and the AlN/β-Ga2O3 SBDs with state-of-art performances open up more opportunities in future power electronics.