Anomalous charge transport in reduced graphene oxide films on a uniaxially strained elastic substrate

Abstract

We investigate temperature-dependent charge transport in reduced graphene oxide (rGO) films coated on flexible polydimethylsiloxane (PDMS) substrates which are subject to uniaxial strain. Variable strain, up to 10%, results in an anisotropic morphology comprising of quasi-periodic linear array of deformations which are oriented perpendicular to the direction of strain. The anisotropy is reflected in the charge transport measurements, when conduction in the direction parallel and perpendicular to the applied strain are compared. Temperature dependence of resistance is measured for different values of strain in the temperature interval 80-300 K. While the resistance increases significantly upon application of strain, the temperature-dependent response shows anomalous decrease in resistance ratio R /R upon application of strain. This observation of favorable conduction processes under strain is further corroborated by reduced activation energy analysis of the temperature-dependent transport data. These anomalous transport features can be reconciled based on mutually competing effects of two processes: (i) thinning of graphene at the sites of periodic deformations, which tends to enhance the overall resistance by a purely geometrical effect, and (ii) locally enhanced inter-flake coupling in these same regions which contributes to improved temperature-dependent conduction.

Multiscale Charge Transport in van der Waals Thin Films: Reduced Graphene Oxide as a Case Study

“…Although a robust quantitative analysis of the experimental data is not possible due to the low signal-to-noise ratio of the ρ­( T ) data, the positive W trend clearly indicates that semiconductive RGO films tend to become quasi-conductive as we increase the film thickness. A similar behavior was already observed by Shaina et al . in thick RGO films (thickness >500 nm) with larger variations of ρ and W values, showing how such regime becomes predominant when films are subjected to uniaxial strain.…”

“…Observed by Govor et al . in self-organized carbon networks and ascribed to the transfer of the charge carriers excited at the mobility edge, such a transition could be described as a MIT induced by temperature, modeling the behavior of resistivity in thick RGO films subjected to uniaxial strain …”

Intercalated water mediated electromechanical response of graphene oxide films on flexible substrates

“…The primary effect of strain is not to stretch the C-C bonds in each flake but rather the relative sliding of electrostatically-bonded layers constituting the film, subsequently leading to the formation of new surfaces in the form of cracks. This is evidenced from the strain-dependent Raman spectra where the G-mode shifts are very small (see supplementary information S7) and this observation is consistent with literature [42]. A comprehensive description of crack propagation in uniaxially strained rGO films process has been previously shown [8].…”

Superlubric-pinned transition of a two-dimensional solid dusty plasma under a periodic triangular substrate

“…Assemblies of interacting collective particles modified by substrates have been widely studied over the past decades in various two-dimensional (2D) systems, including vortices in type-II superconductors [1], colloidal monolayers [2], pattern-forming systems [3,4], electron crystals on a liquid helium surface [5], and dusty plasmas [6]. For these physical systems modified by substrates, a variety of new physical phenomena are discovered, such as directional locking [7], superlubricity or the Aubry transition [8], Shapiro steps [9], anomalous transport [10], and pinning/depinning dynamics [11]. In these studies, the external substrates have various forms, including one-dimensional (1D) periodic substrates [12], 2D periodic substrates [13], quasicrystalline substrates [14], quasiperiodic substrates [15], and even random substrates [16].…”