Carrier transport mechanisms of the writing and the erasing processes for Al/ZnO nanoparticles embedded in a polymethyl methacrylate layer/C60/p-Si diodes.

Transmission electron microscopy images showed that ZnO nanoparticles were randomly distributed inside the polymethyl methacrylate (PMMA) layer. Capacitance-voltage (C-V) measurements on the Al/ZnO nanoparticles embedded in a PMMA layer/C60/p-Si diode at 300 K showed a clockwise hysteresis with a flatband voltage shift due to existence of the ZnO nanoparticles and a C60 buffer layer. The insertion of the C60 layer enlarged the memory window of the device containing the ZnO nanoparticle, as estimated by the flatband voltage shift in the C-V hysteresis. Capacitance-time measurements showed that the devices exhibited excellent memory retention ability at ambient conditions. Operating mechanisms of the charge injection, capture, and emission in the active layer and the charging and the discharging processes in the devices are described on the basis of the C-V results.