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Semiconductor Physics, Quantum Electronics & Optoelectronics. 2006. V. 9, N 4. P. 017-020.
Conductivity and photoconductivity peculiarities observed in C60 layers
Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences
72, “Tzarigradsko chaussee” blvd, 01784 Sofia, Bulgaria
Phone: +3592778448, fax: +35928754016
Abstract. Thin layers of various thickness prepared from C60 with traces of C70 were
studied. They were deposited by thermal evaporation on quartz, glass, p-Si or n-Si
substrates. An apparatus fixing current values every 3 ms was used to measure and
register the kinetics of layer conductivity and photoconductivity. Series of peculiarities
were observed in the kinetics of the current when an electrical field was applied to
illuminated or darkened samples. For example, when voltage is applied to the sample the
current immediately rises to a certain value and then falls to a different quasi-stationary
value. These peculiarities depend on the particular state of the samples. After analyzing
the phenomena, a scheme explaining these peculiarities was proposed which relates
mainly to intrinsic polarization. The influence, which these processes might exert on the
photoconductivity and data accuracy, was discussed. A substantial influence of ambient
humidity was determined. Our study of the observed changes showed that humidity did
not substantially affect the generation-recombination processes in the bulk material, but
predominantly the carrier transport mechanism.
Keywords: photoconductivity, C60, electrical properties and measurements.
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