High-Gain Graphene Transistors with a Thin AlOx Top-Gate Oxide

Abstract

The high-frequency performance of transistors is usually assessed by speed and gain figures of merit, such as the maximum oscillation frequency f max, cutoff frequency f T, ratio f max/f T, forward transmission coefficient S 21, and open-circuit voltage gain A v. All these figures of merit must be as large as possible for transistors to be useful in practical electronics applications. Here we demonstrate high-performance graphene field-effect transistors (GFETs) with a thin AlOx gate dielectric which outperform previous state-of-the-art GFETs: we obtained f max/f T > 3, A v > 30 dB, and S 21 = 12.5 dB (at 10 MHz and depending on the transistor geometry) from S-parameter measurements. A dc characterization of GFETs in ambient conditions reveals good current saturation and relatively large transconductance ~600 S/m. The realized GFETs offer the prospect of using graphene in a much wider range of electronic applications which require substantial gain.

Graphene Field-Effect Transistors With High Extrinsic <inline-formula> <tex-math notation="LaTeX">${f}_{T}$</tex-math> </inline-formula> and <inline-formula> <tex-math notation="LaTeX">${f}_{\mathrm{max}}$</tex-math> </inline-formula>

“…Also shown are the extrinsic f T and f max values obtained in our previous work and the best values published in the literature. It can be seen, that the GFETs in this work reveal higher f T and f max values than that of the best reported GFETs [3], [7], including the GFETs fabricated by our prior technology [4], and even Si MOSFETs [12] at similar gate lengths. The scaling behavior of the GFETs published in [5] and [7] is suppressed, as indicated by the polynomial fitting lines, whereas the GFETs in this work show a promising scaling trend.…”

“…However, even the best reported extrinsic values of f T and f max of GFETs are still below those of n-channel Si MOSFETs with comparable gate lengths [11]- [13]. Furthermore, the increase in f T and f max with scaling down of the gate length has been suppressed [5], [7].…”

Structural and nanochemical properties ofAlOxlayers inAl/AlOx/Al-layer systems

“…Thin AlOx-tunnel barriers with a thickness of ~2 nm are widely used in Al/AlOx/Al-based Josephson junctions (JJs) for superconducting electronic devices like superconducting quantum bits, single-electron transistors, single-photon detectors, radiation detectors and superconducting quantum interference devices in magnetometers [1][2][3][4][5][6][7]. Amorphous AlOx layers with a thickness of a few nanometers are used as gate dielectrics in high-gain graphene field-effect transistors [8,9], as gate oxide in III-V compound semiconductor-based field-effect transistors [10,11] or as layers in non-volatile resitive switching random access memories [12,13]. The structural and nanochemical properties of AlOx layers have a significant influence on the performance of these devices.…”

Theory of Thermionic Carrier Injection in Graphene/Organic Schottky Interface

“…hv F /g svrC . The transfer characteristic curve is calculated by considering a d G = 5 nm thin Al 2 O 3 of ε G = 6.4 as the gate dielectric, which is typically used in graphene field-effect devices (Kim et al, 2009;Pedrinazzi et al, 2017). A rapidly raising injection current density is clearly visible at gate voltages slightly larger than 0, which corresponds to the much enhanced field effect when the Fermi level crosses the Dirac point as discussed above in Figure 2.…”