Graphene thickness-graded transistors with reduced electronic noise

Abstract

We demonstrate graphene thickness-graded transistors with high electron mobility and low 1/f noise (f is a frequency). The device channel is implemented with few-layer graphene with the thickness varied from a single layer in the middle to few-layers at the source and drain contacts. It was found that such devices have electron mobility comparable to the reference single-layer graphene devices while producing lower noise levels. The metal doping of graphene and difference in the electron density of states between the single-layer and few-layer graphene cause the observed noise reduction. The results shed light on the noise origin in graphene.

Reduction of 1/f noise in graphene after electron-beam irradiation

“…The noise spectral density, S I /I 2 , follows 1/f law but reveals the gate-bias dependence different from that in semiconductor field-effect transistors [9][10][11][12][13][14][15]. The noise level was reported to be smaller in bilayer [9] or graded-thickness [14] few-layer graphene than in single-layer graphene. In many cases, the interpretations of measured results were different.…”

“…The envisioned applications require a low level of 1/f noise, which contributes to the phase-noise of communication systems [2] and limits the sensor sensitivity [7]. Despite significant research efforts [9][10][11][12][13][14][15] there is still no conventionally accepted model for physical mechanisms behind 1/f noise in graphene. Correspondingly, no comprehensive methods for 1/f noise suppression in graphene devices have been developed.…”

“…For this study we selected the electron energy of 20 keV in order to exclude the severe knock-on damage to the graphene crystal lattice, which starts at ~50 keV [23]. The back-gated graphene devices were fabricated using mechanical exfoliation [5] and standard lithographic fabrication techniques [10,14]. The number of atomic planes and absence of defects in pristine graphene have been checked with Raman spectroscopy.…”

“…A number of research groups have studied low-frequency noise in graphene devices [9][10][11][12][13][14][15]. The noise spectral density, S I /I 2 , follows 1/f law but reveals the gate-bias dependence different from that in semiconductor field-effect transistors [9][10][11][12][13][14][15].…”

Limits on the bolometric response of graphene due to flicker noise

“…Flicker noise in graphene arises from the fluctuation in the number of charge carriers and their mobility. Techniques to reduce it such as electron irradiation [28][29][30][31][32] can be explored in this context. In addition, the high NEP in graphene is also due to the low sensitivity arising in part because of the weak dependence of the graphene resistance with temperature.…”