Bismuth-metal nanocrystals self-embedded in high-k Bi-based pyrochlore dielectrics grown at room temperature

Abstract

Bismuth-metal nanocrystals (NCs) are self-embedded within high-k Bi 2Mg 2/3Nb 4/3O 7 (BMNO) dielectrics grown at room temperature by rf magnetron sputtering were demonstrated for the low-voltage nonvolatile memory device. The BMNO pyrochlore films grown in Ar/O 2 ambient at room temperature showed the stable dielectric properties, together with high dielectric constant (∼45), small dielectric loss (0.2%), and improved leakage current. Bismuth nanocrystals (a mean size of 2-3 nm) and a high-k BMNO films (∼50 nm thickness) as a control oxide layer were continuously in situ formed at room temperature in Ar and Ar/O 2 ambient, respectively. A significant threshold voltage shift of 0.95 V is observed at a gate voltage of 5 V and the threshold voltage shift linearly increases with increasing gate voltage from 3 to 6 V. The self-embedded bismuth nanocrystals in high-k BMNO dielectrics at room temperature represent a viable candidate for low-voltage NFGM device applications. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.