Observation of impact ionization at sub-0.5V and resultant improvement in ideality in I-NPN selector device by Si epitaxy for RRAM applications

The improvement in ideality is demonstrated by impact ionization at sub-0.5V in silicon despite the higher 1eV band-gap. The NIPIN structure produces high internal field due to the built-in potential (~1eV) of the junctions in addition to Va (cf. a simple pn junction in IMOS) which provides electron sufficient (>bandgap) energy for II. In addition, the dopant profile engineering with i-region to increase scattering length is possibly responsible to effective Impact Ionization at low bias enabling record low bias II (Table 1 that is attractive for advanced memory and logic.