Low-Frequency Current Fluctuations in Graphene-like Exfoliated Thin-Films of Topological Insulators

We report on the low-frequency current fluctuations and electronic noise in thin-films made of bismuth selenide topological insulators. The films were prepared via the graphene-like mechanical exfoliation and used as the current conducting channels in the four- and two-contact devices. Analysis of the resistance dependence on the film thickness indicates that the surface contribution to conductance is dominant in our samples. It was established that the current fluctuations have the noise spectrum close to the pure 1/f in the frequency range from 1 to 10 kHz (f is the frequency). The relative noise amplitude S/I^2 for the examined films was increasing from ~5x10^-8 to 5x10^-6 (1/Hz) as the resistance of the channels varied from ~10^3 to 10^5 Ohms. The obtained noise data is important for understanding electron transport through the surface and volume of topological insulators, and proposed applications of this class of materials.