MOBILITIES OF CHARGE-CARRIERS IN C-60 ORTHORHOMBIC SINGLE-CRYSTAL

Time-of-flight technique has been used to measure mobilities of electr ons and holes in C60 orthorhombic single crystals at room temperature. Single crystals of C60 grown from the CS2 solution have been characte rized as having about 10(14) cm-3 deep trapping sites for electrons an d holes. The mobility for holes (mu(h)) at room temperature is 1.1 +/- 0.1 cm2 Vs and that for electrons is found within the same limits. Te mperature dependence of mu(h) is revealed to be almost constant from 3 25 to 250 K. Mu(h) starts increasing and below 250 K may be approximat ed by the law mu(h) approximately exp (DELTAE/kT) with DELTAE = 0.053 eV. Coincidence of the point of the increase of hole mobility with the phase transition temperature is worthy to be noted.