Effects of some physical parameters on the electrical current oscillations in vapor adsorbed ferrocene

This work deals with the observation of low-frequency electrical current oscillations in a ferrocene sample in the presence of adsorbed ethanol vapor in a sandwich-type cell configuration. The effects of some physical parameters such as (i) vapor pressure, (ii) temperature when adsorption of vapors is completed, (iii) cell temperature during current measurement and (iv) bias voltages on the oscillatory behavior of current have been studied. The current measurements were performed with different bias voltages (27–300 V) at some fixed temperatures in the range from 272 to 300 K for adsorption of vapors at 20, 25, 30, 35 and 40 Torr vapor pressure. This experiment has shown that the frequency of current oscillations increases exponentially with the increase of vapor pressure, when other experimental conditions remained the same. The frequency of oscillations and the current peak height depend on the cell temperature during adsorption as well as measurement of current. With increasing bias, a decrease in frequency of oscillations along with an increase in peak height has been observed for an experiment with a fixed vapor pressure. Existing theories of current oscillations in semiconductors have failed to explain the observed low-frequency current oscillations in this organometallic semiconductor. The results have been discussed.