Selector devices that can be suitable for memory device applications can have low leakage currents at low voltages to reduce sneak current paths for non selected devices, and high leakage currents at high voltages to minimize voltage drops during device switching. The selector device can include a first electrode, a tri-layer dielectric layer, and a second electrode. The tri-layer dielectric layer can include a low band gap dielectric layer disposed between two higher band gap dielectric layers. The high band gap dielectric layers can be doped with doping materials to form traps at energy levels higher than the operating voltage of the memory device.