Ovonic threshold switching selectors are indispensable for suppressing sneak currents in dense cross-point memories, but most established selector materials still rely on multicomponent chalcogenides with persistent trade-offs in leakage current, reliability, and compositional stability. Recent progress in elemental switching materials is beginning to change this picture. A new study identifies amorphous selenium as a highly effective selector, combining an ultralow leakage current of 4 × 10^–12 A, an on/off ratio above 10⁸, a drive current density of 21.2 MA cm^–2, nanosecond-scale switching, and endurance up to 2 × 10⁹ cycles. More importantly, spectroscopy and theory connect these metrics to a charge-triggered mechanism rooted in dense trap pairs in the amorphous network. These states strongly pin the Fermi level in the off-state, while field-induced carrier release near threshold drives abrupt conduction. Beyond introducing a new selector material, this work suggests that monatomic chalcogens may provide a cleaner platform for understanding and engineering threshold switching, with fewer complications from phase segregation, cation migration, and chemical overdesign.

Highlights:
1 Amorphous elemental selenium delivers ultralow leakage, high selectivity, fast switching, and long endurance as an ovonic threshold switching selector.
2 Dense trap pairs in amorphous selenium pin the Fermi level in the off-state, whereas field-driven carrier release and avalanche multiplication trigger abrupt turn-on.
3 Recent progress in pure Te and pure Se suggests that monatomic switching materials may provide a scalable alternative to compositionally complex selectors.