LOW-FREQUENCY ELECTRICAL-CURRENT OSCILLATIONS IN THE VAPOR-ADSORBED STATE OF SOME FERROCENE DERIVATIVES

Low-frequency oscillations in electrical (dark, i.e., unilluminated) c urrent as a function of time have been observed in a specific temperat ure range in samples of some ferrocene derivatives, namely ferroceneca rboxylic acid, ferrocenecarbaldehyde and acetylferrocene, with adsorbe d ethanol vapor at a pressure of 40 Torr in a sandwich-type cell. The dependence of the oscillatory behavior of current on the applied bias voltage across the electrodes has also been studied at a constant samp le cell temperature for each material in the ethanol-vapor-adsorbed st ate. With increasing bias, increases in both the time interval between two consecutive current peaks (i.e. decrease in frequency of current oscillations) and current peak hight were observed for all of the mate rials studied. The oscillatory behavior of the current and the tempera ture at which oscillations occurred depended on the nature of the ferr ocene derivative. Existing theories of current oscillations in semicon ductors have failed to explain the observed low-frequency current osci llations in these organometallic semiconductors. Such current oscillat ions are possibly associated with some kind of time-dependent phase ch anges in the ferrocene derivative-ethanol system at the sample surface layer.