Switching Time in Ferroelectric Organic Field‐Effect Transistors

Ferroelectric organic field‐effect transistors (Fe‐OFETs) are considered a promising technology to develop flexible and low‐cost nonvolatile memories. Although their switching time between program‐state and erase‐state forms an important aspect of their functionality, it is still unclear as to what parameters dominate the switching time. Two possible parameters that influence the switching time are the channel formation of the semiconductor layer and the ferroelectric polarization in the ferroelectric layer. In this study, the origin of the switching time of the Fe‐OFETs is experimentally clarified. The switching times of Fe‐OFETs and ferroelectric capacitors are independently measured. Programming time of the Fe‐OFETs is limited by the above two times as expected; however, the ferroelectric polarization is not negligible and limited the time in most of cases. Additionally, it is found that switching time from depolarized erase‐state to polarized program‐state in the Fe‐OFETs is comparable to the ferroelectric polarization time in the ferroelectric capacitor. On the other hand, erasing time of the Fe‐OFETs is much slower than their programing time due to the depletion layer in the semiconductor layer. The erasing time can be predicted by taking a series capacitance made by depleted semiconductor layer into consideration. Programming/erasing times of ferroelectric organic field‐effect transistors (Fe‐OFETs) are studied. The asymmetry switching times between depolarized erase‐state and polarized program‐state areobserved. Programming time in the Fe‐OFET is comparable to ferroelectric polarization time in ferroelectric capacitor. On the other hand, erasing time is much slower than the programing time due to the depleted semiconductor layer.