Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation.

Filippo Giubileo,Antonio Di Bartolomeo,Francesco Romeo,Laura Iemmo,Maurizio Passacantando,Nadia Martucciello,Paola Romano

doi:10.3390/nano6110206

Filippo Giubileo, Antonio Di Bartolomeo + Show 5 more

Open Access

https://doi.org/10.3390/nano6110206

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Abstract

We studied the effects of low-energy electron beam irradiation up to 10 keV on graphene-based field effect transistors. We fabricated metallic bilayer electrodes to contact mono- and bi-layer graphene flakes on SiO2, obtaining specific contact resistivity and carrier mobility as high as 4000 cm2·V−1·s−1. By using a highly doped p-Si/SiO2 substrate as the back gate, we analyzed the transport properties of the device and the dependence on the pressure and on the electron bombardment. We demonstrate herein that low energy irradiation is detrimental to the transistor current capability, resulting in an increase in contact resistance and a reduction in carrier mobility, even at electron doses as low as 30 e−/nm2. We also show that irradiated devices recover their pristine state after few repeated electrical measurements.

Highlights

Graphene is a promising candidate for future nanoelectronics and has been attracting an enormous amount of attention from the scientific community since 2004, when graphene flakes were exfoliated from graphite for the first time in Manchester [1]
Graphene has reignited the idea of carbon-based electronics, offering unmatched properties such as a linear dispersion relation, with electrons behaving as massless Dirac fermions [3], a very high carrier mobility [4], and a superior current density capability [5]
The use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron beam lithography (EBL), and focus ion beam (FIB) processing in an ultra-high vacuum represents a necessary step for the fabrication and characterization of graphene-based devices

Summary

Introduction

Graphene is a promising candidate for future nanoelectronics and has been attracting an enormous amount of attention from the scientific community since 2004, when graphene flakes were exfoliated from graphite for the first time in Manchester [1]. Several experiments have shown that the irradiation of energetic particles, such as electrons [12,13,14,15,16] and ions [17,18], can induce defects and damages in graphene and cause a severe modifications of its properties. Raman spectroscopy has been largely used to study electron-beam induced structural modifications [19,20,21], or formation of nanocrystalline and amorphous carbon [18,22], and to correlate the reduction in 1/f noise in graphene devices with an increasing concentration of defects [23]. Raman spectroscopy is unable to reveal all the effects of e-beam irradiation, and electrical measurements are needed to check for possible modifications of transport properties. For low energy electron irradiation, the conditions of pristine devices are almost restored by successive gate voltage sweeps

Materials and Methods

Results and Discussion

Effect of Electron Beam Irradiation