Efficient and Dense Electron Emission from a SiO₂ Tunneling Diode with Low Poisoning Sensitivity

We report a tunneling diode enabling efficient and dense electron emission from SiO₂ with low poisoning sensitivity. Benefiting from the shallow SiO₂ channel exposed to vacuum and the low electron affinity of SiO₂ (0.9 eV), hot electrons tunneling into the SiO₂ channel from the cathode of the diode are efficiently emitted into vacuum with much less restriction in both space and energy than those in previous tunneling electron sources. Monte Carlo simulations on the device performance show an emission efficiency as high as 87.0% and an emission density up to 3.0 × 10⁵ A/cm². By construction of a tunneling diode based on Si conducting filaments in electroformed SiO₂, an emission efficiency up to 83.7% and an emission density up to 4.4 × 10⁵ A/cm² are experimentally realized. Electron emission from the devices is demonstrated to be independent of vacuum pressure from 10^-4 to 10^-1 Pa without poisoning.