Nonequilibrium mesoscopic conductance fluctuations as the origin of 1/f noise in epitaxial graphene

Abstract

We investigate the 1/f noise properties of epitaxial graphene devices at low temperatures as a function of temperature, current, and magnetic flux density. At low currents, an exponential decay of the 1/f noise power spectral density with increasing temperature is observed that indicates mesoscopic conductance fluctuations as the origin of 1/f noise at temperatures below 50 K. At higher currents, deviations from the typical quadratic current dependence and the exponential temperature dependence occur as a result of nonequilibrium conditions due to current heating. By applying the Kubakaddi theory [S. S. Kubakaddi, Phys. Rev. B 79, 075417 (2009)], a model describing the 1/f noise power spectral density of nonequilibrium mesoscopic conductance fluctuations in epitaxial graphene is developed and used to determine the energy loss rate per carrier. In the regime of Shubnikov-de Haas oscillations, a strong increase of 1/f noise is observed, which we attribute to an additional conductance fluctuation mechanism due to localized states in quantizing magnetic fields. When the device enters the regime of quantized Hall resistance, the 1/f noise vanishes. It reappears if the current is increased and quantum Hall breakdown sets in.

Epitaxial graphene for quantum resistance metrology

“…Considering a measurement temperature of a typical closed-cycle table-top cryostat operating between 2.8 K and 4.2 K, QHR standards could be maintained at magnetic flux densities between 1 T and 4 T for graphene as indicated by the blue shaded area in figure 7(a). Reasons for why the energy splitting of the LLs must be at least 100 times larger than the thermal energy include electron heating at higher currents and inhomogeneities in the charge carrier density of the sample [49, 67]. Figure 7(b) shows the density of states between the two LLs n LL = 0 and n LL = 1 forming the i = 2 resistance plateau in graphene as a function of the Fermi energy E F [68].…”

Universal Conductance Fluctuation Due to Development of Weak Localization in Monolayer Graphene

“…In addition, we would like to mention the temperature dependence result of 1/ f noise measurement. From 1/ f noise measurement, it was reported that the noise power spectral density strongly increases with decreasing T below 50 K (the temperature below which the conductance fluctuation starts to appear). The increasing 1/ f noise is considered to be originated in the quantum interference effect, thus our observation is consistent with this result.…”

“…UCF occurs due to the interference among different scattering paths when electron travels through a disordered conductor, whereas WL is a manifestation of the interference between two pair of closed time‐reversal paths. In graphene, many works were dedicated to these quantum interference phenomena . Interestingly, the topological properties of two valleys in the momentum space in graphene cause essential changes in the quantum interference effect.…”

1 / f noise in van der Waals materials and hybrids

“…Studying 1/f noise in graphene is important not only from an applied perspective but is also fundamentally intriguing, for graphene hosts unique Dirac charge carriers that can be electrostatically tuned between electrons and holes along with their number density. As a result, noise has been extensively studied in graphene devices for a large range of mobility values, varying device configurations, and substrate types [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][63][64][65][66][67][68][69][70][71][72][73]. Basic graphene devices consist of graphene exfoliated typically on a 300 nm of oxide grown on top of highly doped silicon, which acts as the back gate.…”

“…It has been reported recently that this anomalous behavior depends on the bias applied may occur due to the pinning of electron-hole puddle [97]. While oxide traps are responsible for noise in graphene in the high-temperature range (80-300 K), at lower temperatures (< 50 K) quantum interference of Dirac carriers determines the magnitude of low-frequency noise [98][99][100], and increased sensitivity on defect motion may lead to an increase in noise with decreasing temperature [72]. Apart from the oxide traps, water vapor has also been shown to affect the noise generated [55] but it is not clear what role do other impurities, like resist residues and adsorbates play in the generation of flicker noise.…”