Resonant tunneling characteristics in SiO2/Si double-barrier structures in a wide range of applied voltage

We have found that current–voltage characteristics of resonant tunneling diodes (RTDs) with a structure of Al/upper-SiO2/p−-Si-well/lower-SiO2/n+-Si substrate are distinctly categorized by the kinetic energy of electrons in the Si well injected from the n+-Si substrate. For RTDs with a lower-SiO2-layer thickness below 4 nm, negative differential conductance is observed in accordance with our previous work [Y. Ishikawa, T. Ishihara, M. Iwasaki, and M. Tabe, Electron. Lett. 37, 1200 (2001)], where electrons have relatively low kinetic energies below 2.7 eV in the Si well. On the other hand, RTDs with a lower-SiO2 layer thicker than 5 nm have specific characteristics of a large current peak and a large hysteresis at higher kinetic energies above 2.9 eV, indicating that hot electrons are readily stored in the Si well, probably due to enhanced impact ionization scattering.