由于高载流子迁移率和饱和速度的结合,低固有电容,和出色的稳定性,碳纳米管(CNT)已被认为是构建具有超高频带的射频(RF)场效应晶体管(FET)和电路的理想半导体。然而,报告的CNTRFFET通常表现出较差的实际性能,如测量的最大振荡频率(fmax)所示,然后是放大器,最重要和最基本的射频电路,遭受低功率增益和低频带。在这项工作中,我们在溶液衍生的随机取向CNT薄膜上构建RF晶体管,具有改进的质量和均匀性。随机取向的CNT薄膜FET表现出记录的90GHz的最大fmax,展示了超过28GHz(至少90GHz的三分之一)5G毫米波(频率范围2)应用的潜力。受益于CNT薄膜的大规模均匀性,FET的设计和制造具有较大的沟道宽度,可为标准的50Ω阻抗匹配引导线提供较低的内部电阻,这对于构建RF放大器至关重要。此外,我们首先演示放大器的最大功率增益高达11dB,输出三阶截点(OIP3)为15dBm,都在K波段,这代表了CNT放大器的记录,甚至与基于III-VRF晶体管的商用放大器相当。
Owing to the combination of high carrier mobility and saturation velocity, low intrinsic capacitance, and excellent stability, the carbon nanotube (CNT) has been considered as a perfect semiconductor to construct radio frequency (RF) field-effect transistors (FETs) and circuits with an ultrahigh frequency band. However, the reported CNT RF FETs usually exhibited poor real performance indicated by the as-measured maximum oscillation frequency (fmax), and then the amplifiers, which are the most important and fundamental RF circuits, suffered from a low power gain and a low frequency band. In this work, we build RF transistors on solution-derived randomly orientated CNT films with improved quality and uniformity. The randomly orientated CNT film FETs exhibit the record as-measured maximum fmax of 90 GHz, demonstrating the potential for over 28 GHz (at least one-third of 90 GHz) 5G mmWave (frequency range 2) applications. Benefiting from the large-scale uniformity of CNT films, FETs are designed and fabricated with a large channel width to present low internal resistance for the standard 50 Ω impedance matching guide line, which is critical to construct an RF
amplifier. Furthermore, we first demonstrate amplifiers with a maximum power gain up to 11 dB and output third-order intercept point (OIP3) of 15 dBm, both at the K-band, which represents the record of a CNT
amplifier and is even comparable with a commercial
amplifier based on III-V RF transistors.