Low operational voltage and high performance organic field effect memory transistor with solution processed graphene oxide charge storage media

Abstract

Low voltage organic field effect memory transistors are demonstrated by adapting a hybrid gate dielectric and a solution processed graphene oxide charge trap layer. The hybrid gate dielectric is composed of aluminum oxide (AlOx) and [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) plays an important role of both preventing leakage current from gate electrode and providing an appropriate surface energy to allow for uniform spin-casting of graphene oxide (GO). The hybrid gate dielectric has a breakdown voltage greater than 6V and capacitance of 0.47μF/cm2. Graphene oxide charge trap layer is spin-cast on top of the hybrid dielectric and has a resulting thickness of approximately 9nm. The final device structure is Au/Pentacene/PMMA/GO/PhO-19-PA/AlOx/Al. The memory transistors clearly showed a large hysteresis with a memory window of around 2V under an applied gate bias from 4V to −5V. The stored charge within the graphene oxide charge trap layer was measured to be 2.9×1012cm−2. The low voltage memory transistor operated well under constant applied gate voltage and time with varying programming times (pulse duration) and voltage pulses (pulse amplitude). In addition, the drain current (Ids) after programming and erasing remained in their pristine state after 104s and are expected to be retained for more than one year.