Nonvolatile memory devices based on ZnO/polyimide nanocomposite sandwiched between two C-60 layers

The memory effects of a three-layer nonvolatile memory device Al/C-60/ZnO nanoparticles embedded in a polyimide (PI) layer/C-60/p-Si were investigated by using capacitance-voltage (C-V) measurements. Transmission electron microscopy and selected area electron diffraction pattern measurements showed that ZnO nanocrystals were formed inside the PI layer. The insertion of C-60 layer improved the charge trap state density in the ZnO nanoparticle. The density was estimated by the flatband voltage shift in the C-V hysteresis, which increases with the max sweep voltage. Possible operating mechanisms corresponding to the charging and discharging process in the structure are proposed on the basis of the C-V results. (C) 2009 Elsevier B.V. All rights reserved