Graphene/lead-zirconate-titanate ferroelectric memory devices with tenacious retention characteristics

With the motivation of realizing the high performance graphene-based nonvolatile memory devices, we fabricate and characterize reliable and robust ferroelectric field-effect transistor (FFETs), which are composed of single-layer graphene (SLG) and lead-zirconate-titanate (PZT). After completing all of the fabrication steps, the samples are annealed in vacuum to improve the device characteristics. Through systematic analyses, we investigate an optimal vacuum-annealing condition for improving the memory characteristics of the device. At annealing temperatures at 250–300 °C, both the electrical conduction properties of the SLG channel and the capacitive-coupling abilities of the SLG/PZT/Pt stack are dramatically improved because of the elimination of chemical residues and/or molecular oxygens. Consequently, the vacuum-annealed SLG-PZT FFET displays a great improvement of data retention (∼72% after 10 year) and a large memory window (∼4.1 V). We believe the present study can provide alternative avenues for exploring unprecedented graphene-based memory structures.