Ferroelectric Na0.5K0.5NbO3/SiO2/Si thin film structures for nonvolatile memory

Highly c-axis oriented Na0.5K0.5NbO3 (NKN) films have been prepared on thermally, grown thin SiO2 template layer onto Si(001) wafer by pulsed laser deposition technique. Xray diffraction theta -2 theta -scan data show multiple-cell structuring along the polar axis in NKN films grown onto SiO2 with thickness up to 45 nm. On the other hand, the film deposited onto amorphous ceramic (Coming) glass is a mixture of slightly c-axis oriented NKN and pyrochlore phases, while the film onto Pt(111)/Ti/SiO2/Si(001) shows perfect [111] orientation. This implies small amount of SiO2 crystallites distributed in amorphous silica matrix inherits Si(001) orientation and serves as a key factor in highly oriented growth of NKN films. Au upper electrodes have been defined on the top of NKN(270nm)/SiO2/Si structures to investigate Metal-Ferroelectric-Insulator-Silicon (MFIS) diode characteristics for Field Effect Transistor (MFIS-FET) nonvolatile memory applications. C-V measurements yield memory window of 4.14 V at 10 V of gate voltage.