Effects of neutron irradiation of ultra-thin HfO2 films

Neutron irradiation at low fluence decreases the Pb-type and E' defect levels in ultra-thin hafnium dioxide films because electrons can fill existing states. These electrons come from electron-hole pairs generated by neutron interactions with silicon and oxygen. Thus, a low fluence of neutrons "anneals" the sample. However, when neutron fluence increases, more neutrons collide with oxygen atoms and cause them to leave the lattice or to transmute into different atoms. This causes the E' states to increase. As defect-state concentrations increase, leakage currents increase, but since the E' is much lower than the Pb concentration, this is not a dominant factor. (C) 2014 AIP Publishing LLC.