Nanographene is a potential charge trapping material that benefits from high density of states, work function, high temperature stability and low dimensionality. By combing bottom-up and top-down approaches, Meng et al. demonstrate that the density of nanographene sheets can be achieved as high as 3.6×1012 cm-2.

Nanographene sheets

The obtained nanographene sheets allow the researchers to incorporate them into a capacitor structure of Si (p++)/SiO2 (4nm)/nanographene/Al2O3 (15nm)/Ti-Au. A memory window of ~9 V at a sweep voltage of ±8 V is observed, and this broad window is the main advantage of a monolayer graphene-based CTM. In addition, the researchers characterise a program/erase speed of ~10 ms and a robust endurance of >1000 cycles.

Prototype

The good performance of high-density nanographene-based CTM provides a prototype for future miniaturised memory devices. According to the International Technology Roadmap for Semiconductors (ITRS), only 10 nanocrystals will exist in a single memory cell in 2020, therefore, high-density nanographene CTM opens a new perspective for future scaling. However, the precise control of the nanographene density and size still needs further exploration to meet the technical standard required.

More information about this research can be found in the journal Nanotechnology 26 455704.

Further reading

Transistor memory devices with large memory windows (Dec 2014)
Ultrathin oxide induced non-volatile nanowire memory performs when bent (Aug 2013)
Understanding nonvolatile memory phenomena in graphene-polymer devices (Aug 2014)