Advantage of the structure and the electrical properties of epitaxial ultra-thin zirconia gate dielectrics

For this study, the authors fabricated non-doped 0 0 1 epitaxial ZrO2 gate dielectrics with small density of extrinsic defects and charges in the size effect. Wide-angle X-ray reciprocal space mapping and high-resolution transmission electron microscope (HRTEM) analyses showed many 90° and 180° domains. The 0 0 1 planes nearly align in the out-of-plane direction for 17-nm ZrO2 thin films. On the other hand, the nanoscale monoclinic phase precipitated coherently in a tetragonal matrix for 3-nm ZrO2 thin films. Capacitance–voltage (C–V) measurements suggest that the C–V curve of ZrO2 thin film has a charge-injection type hysteresis. The width is 26 mV for the 17-nm ZrO2 thin film and less than 2 mV for the 3-nm ZrO2 ultra-thin film.