β‑Ga₂O₃ Air-Channel Field-Emission Nanodiode with Ultrahigh Current Density and Low Turn-On Voltage

Field-emission nanodiodes with air-gap channels based on single β-Ga₂O₃ nanowires have been investigated in this work. With a gap of ∼50 nm and an asymmetric device structure, the proposed nanodiode achieves good diode characteristics through field emission in air at room temperature. Measurement results show that the nanodiode exhibits an ultrahigh emission current density, a high enhancement factor of >2300, and a low turn-on voltage of 0.46 V. More impressively, the emission current almost keeps constant over a wide range (8 orders of magnitude) of air pressures below 1 atm. Meanwhile, the fluctuation in field-emission current is below 8.7% during long-time monitoring, which is better than the best reported field-emission device based on β-Ga₂O₃ nanostructures. All of these results indicate that β-Ga₂O₃ air-gapped nanodiodes are promising candidates for vacuum electronics that can also operate in air.