Effects of forming gas annealing on the memory characteristics of Ge nanocrystals embedded in LaAlO 3 high- k dielectrics for flash memory device application

Abstract

Forming gas (FG) annealing effects of a nonvolatile flash memory structure using Ge nanocrystals (NCs) floating gate embedded in LaAlO 3 high- k tunneling/control oxide were studied. Atomic force microscopy and high-resolution transmission electron microscopy measurements revealed that the pulsed-laser deposited Ge NCs were well self-organized and the average diameter of the sphere-like NCs was around 6 nm. By using a double sweep capacitance–voltage measurement, memory windows of 1.4 and 1.0 V were obtained for the as-deposited and FG annealed samples, respectively. The charge loss rate of the FG annealed sample was lower than that of the as-deposited sample, and this could be explained by the decrease of defects in the dielectrics and Ge NCs as well as their interfacial states that may have acted as charge leak channels.