IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598, United States.
Nano Lett. 2011 Sep 14;11(9):3690-3. doi: 10.1021/nl2016637. Epub 2011 Aug 5.
While graphene transistors have proven capable of delivering gigahertz-range cutoff frequencies, applying the devices to RF circuits has been largely hindered by the lack of current saturation in the zero band gap graphene. Herein, the first high-frequency voltage amplifier is demonstrated using large-area chemical vapor deposition grown graphene. The graphene field-effect transistor (GFET) has a 6-finger gate design with gate length of 500 nm. The graphene common-source amplifier exhibits ∼5 dB low frequency gain with the 3 dB bandwidth greater than 6 GHz. This first AC voltage gain demonstration of a GFET is attributed to the clear current saturation in the device, which is enabled by an ultrathin gate dielectric (4 nm HfO(2)) of the embedded gate structures. The device also shows extrinsic transconductance of 1.2 mS/μm at 1 V drain bias, the highest for graphene FETs using large-scale graphene reported to date.
虽然石墨烯晶体管已经证明能够实现千兆赫兹范围内的截止频率，但由于零带隙石墨烯中缺乏电流饱和，将这些器件应用于射频电路在很大程度上受到了阻碍。在此，首次使用大面积化学气相沉积生长的石墨烯演示了高频电压放大器。该石墨烯场效应晶体管 (GFET) 采用 6 指栅设计，栅长为 500nm。石墨烯共源放大器具有约 5dB 的低频增益，3dB 带宽大于 6GHz。这是首次对 GFET 的交流电压增益进行演示，这归因于器件中明显的电流饱和，这是通过嵌入式栅极结构的超薄栅介质（4nmHfO2）实现的。该器件在 1V 漏极偏置下还表现出 1.2mS/μm 的外跨导，这是迄今为止报道的使用大规模石墨烯的石墨烯 FET 中的最高值。
