Phys. Rev. B 95, 045308 (2017)
M. Zoraghi, J. Barzola-Quiquia, M. Stiller, A. Setzer, P. Esquinazi, G.H. Klöß, T. Münster. T. Lühmann, and I. Estrela-Lopis
Abstract
The electrical, in-plane resistance as a function of temperature R(T) of bulk and mesoscopic thin graphite flakes obtained from the same batch was investigated. Samples thicker than ∼30 nm show metalliclike contribution in a temperature range that increases with the sample thickness, whereas a semiconductinglike behavior was observed for thinner samples. The temperature dependence of the in-plane resistance of all measured samples and several others from literature can be very well explained between 2 and 1100 K assuming three contributions in parallel: a metalliclike conducting path at the interfaces between crystalline regions, composed of two semiconducting phases, i.e., Bernal and rhombohedral stacking. From the fits of R(T) we obtain a semiconducting energy gap of 110 ± 20 meV for the rhombohedral and 38 ± 8 meV for the Bernal phase. The presence of these crystalline phases was confirmed by x-ray diffraction measurements.We review similar experimental data from literature of the last 33 years and two more theoretical models used to fit R(T).