Model based precise analysis of the injection currents in Al/ZrO2/Al2O3/ZrO2/SiO2/Si structures for use in charge trapping non-volatile memory devices

Metal/insulator/Silicon (MIS) capacitors containing multilayered ZrO2/Al2O3/ZrO2/SiO2 dielectric were investigated in order to evaluate the possibility of their application in charge trapping non-volatile memory devices. The ZrO2/Al2O3/ZrO2 stacks were deposited by reactive rf magnetron sputtering on 2.4 nm thick SiO2 thermally grown on p-type Si substrate. C–V characteristics at room temperature and I–V characteristics recorded at temperatures ranging from 297 K to 393 K were analyzed by a comprehensive model previously developed. It has been found that Poole-Frenkel conduction in ZrO2 layers occurs via traps energetically located at 0.86 eV and 1.39 eV below the bottom of the conduction band. These levels are identified as the first two oxygen vacancies related levels in ZrO2, closest to its conduction band edge, whose theoretical values reported in literature are: 0.80 eV, for fourfold, and 1.23 eV, for threefold coordinated oxygen vacancies.