Impact of gate work-function on memory characteristics in Al2O3/HfOx/Al2O3/graphene charge-trap memory devices

Graphene-based non-volatile memory devices composed of a single-layer graphene channel and an Al2O3/HfOx/Al2O3 charge-storage layer exhibit memory functionality. The impact of the gate material's work-function (Phi) on the memory characteristics is investigated using different types of metals [Ti (Phi(Ti) = 4.3 eV) and Ni (Phi(Ni) = 5.2 eV)]. The ambipolar carrier conduction of graphene results in an enlargement of memory window (Delta V-M), which is similar to 4.5 V for the Ti-gate device and similar to 9.1 V for the Ni-gate device. The increase in Delta V-M is attributed to the change in the flat-band condition and the suppression of electron back-injection within the gate stack. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3675633]