Electroluminescence, Bistable Switching, and Dielectric Breakdown of Nb2O5 Diodes

Nb–Nb 2 O 5 –metal diodes, after voltage breakdown, exhibit current-controlled negative resistance and switching between two stable conduction states. Before breakdown, Nb–Nb2O5–Au diodes are electroluminescent with hole injection occurring at the Nb2O5–Au interface. After breakdown, electroluminescence is closely related to switching. The energy of emitted radiation has maxima at 1.3 and 1.6 eV. Electroluminescence is both polarity- and voltage-dependent, indicating that hole injection, not heating, produces electroluminescence. Increased electroluminescence accompanies diode switching. Microscopic observation shows that bistable switching and dielectric breakdown of Nb–Nb2O5–Au diodes occur at small conducting regions in the oxide. Destructive dielectric breakdown in Nb–Nb2O5–Cu diodes differs from that in Nb–Nb2O5–Au diodes.