Fully-transparent graphene charge-trap memory device with large memory window and long-term retention

Abstract

A fully-transparent graphene-based charge-trap memory device was realized by fabricating a graphene-channel field-effect transistor with high-k/low-k/high-k oxide stacks of Al2O3/AlOx/Al2O3 and indium-tin-oxide gate/source/drain electrodes on the polyethylene naphthalate substrate (i.e., ITO-gated AXA-gFET). The usage of low-k AlOx as a charge-trap layer allowed us to demonstrate a high-performance memory device, exhibiting a large memory window of ∼9.2 V and a tenacious retention of the memory window margin up to ∼57% after 10 years. Memory cells comprising the ITO-gated AXA-gFET arrays displayed a high transparency with the average optical transmittance of ∼83% in visible wavelength regions. These properties may move us a step closer to the practical application of graphene-based memories for future transparent electronics. In-depth analyses on the electrical characteristics and the mechanisms of the memory functions are presented.