Investigation of Quantum Effects, in Carbonaceous Materials, Near the Metal-Insulator Transition, by Means of THz Photoconductivity

V.A. Dorosinets a, V.K. Ksenevich a, D. Seliuta b, Z. Martūnas b and G. Valušis b a Belarussian State University, Nezaliezhnasti av.4, 220030 Minsk, Belarus b Semiconductor Physics Institute, A. Goštauto 11, LT- 01108 Vilnius, Lithuania

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Received: 26 08 2007;

A series of carbonaceous fibers with conductivity tuned to the metal-insulator transition were prepared by heat treatment of chemically modified polymer precursors. Peculiar behaviour of the resistivity versus temperature dependence R(T) at low temperatures suggests quantum corrections to the Drude conductivity due to weak localization and electron-electron interaction dominating in the conductivity. The THz conductivity method is employed to study the modification of the density of states and provides evidence for a strong change in density of states at the Fermi level caused by the quantum effects.

DOI: 10.12693/APhysPolA.113.875 PACS numbers: 71.30.+h, 72.15.Rn