Fabrication and electrical properties of field effect transistor based on ferroelectric insulator and pentacene film

A field effect transistor (FET) based on the ferroelectric tri-glycine sulfate (TGS) single crystal and pentacene film has been fabricated and the electrical properties have been investigated. It was found that the drain current decreases drastically with the increase of the gate electric field at around 100 V/cm, and shows a minimum at 400 V/cm which corresponds to the coercive electric field of TGS. This decrease of the drain current is caused by the appearance of the depletion layer in the pentacene film. This result indicates that the FET based on the TGS single crystal and pentacene film operates at low gate electric field owing to the rapid generation of the surface charge accompanied by the appearance of the spontaneous polarization in the ferroelectric TGS insulator. It was also found that the drain current does not return to the initial value (before the gate electric field of 450 V/cm is applied) for one week even if the gate electric field is turned from 450 to 0 V/cm. This result indicates that the surface charge of pentacene remains for one week. From these results, it is suggested that the FET based on the TGS single crystal and pentacene film shows the memory effect.