Charge Carrier Transport and Localized States in Graphite-like Amorphous Carbon Films at Room Temperatures

The conductivity of direct and alternating current for graphite-like amorphous carbon films after annealing in vacuum at a temperature of 700 °C was studied. The I-V characteristics of such films are symmetrical. The I-V curve in logarithmic coordinates demonstrated the presence of two linear sections. A study of the frequency dependences of structures with a thin graphite-like amorphous carbon film showed a sharp increase in capacitance at low frequencies and a decrease in the high-frequency region. The increase in capacitance in the low-frequency region is explained by the Maxwell-Wagner polarization, which is observed in inhomogeneous dielectrics with conducting inclusions. The results of temperature measurements of resistance showed that at room temperatures, there is a mechanism of conduction of electrons with a variable jump length along localized states lying in a narrow energy band near the Fermi level. At the same time, with an increase in the injection current, an additional mechanism of hopping electrical transport with a variable jump length along localized states in the tail of the valence band arises, which leads to an increase in the conductivity of the films.