Enhanced High-Frequency Performance of Top-Gated Graphene FETs Due to Substrate- Induced Improvements in Charge Carrier Saturation Velocity

The high-frequency performance of top-gated graphene field-effect transistors (GFETs) depends to a large extent on the saturation velocity charge carriers, limited by inelastic scattering surface optical phonons from dielectrics surrounding channel. In this work, we show that, simply changing channel dielectric with material having higher phonon energy, one could improve transit frequency and maximum oscillation GFETs. We fabricated GFETs conventional SiO 2 /Si substrates adding thin Al O xmlns:xlink="http://www.w3.org/1999/xlink">3 interfacial buffer layer top substrates, about 30% energy than that , compared without layer. From S-parameter measurements, 43 46 GHz, respectively, were obtained for 0.5- $\mu \text{m}$ gate length. These values are approximately those state-of-the-art same length . For relating improvement GFET improvements in carrier velocity, used standard methods extract time. A comparison between two sets showed had increased notation="LaTeX">$1.5\cdot 10^{{7}}$ notation="LaTeX">$2\cdot cm/s.