  We realized an organic electrical memory device with a simple structure based
on single layer pentacene film embedded between Al and ITO electrodes. The
optimization of the thickness and deposition rate of pentacene resulted in a
reliable device with an ON/OFF current ratio as high as nearly 1000000 which
was two orders of magnitude higher than previous results, and the storage time
was more than 576 hrs. The current transition process is attributed to the
formation and damage of the interface dipole at different electric fields, in
which the current conduction showed a transition from Ohmic conductive current
to Fowler?Nordheim tunnelling current. After the transition from ON state to
OFF state, the device tended to remain in OFF state even when the applied
voltage was removed, which indicated that the device was very promising for
write-once read-many-times (WORM) memory.
