EFFECTS OF SOME PHYSICAL PARAMETERS ON THE ELECTRICAL-CURRENT OSCILLATIONS IN VAPOR ADSORBED FERROCENE

This work deals with the observation of low-frequency electrical curre nt oscillations in a ferrocene sample in the presence of adsorbed etha nol vapor in a sandwich-type cell configuration. The effects of some p hysical parameters such as (i) vapor pressure, (ii) temperature when a dsorption of vapors is completed, (iii) cell temperature during curren t measurement and (iv) bias voltages on the oscillatory behavior of cu rrent have been studied. The current measurements were performed with different bias voltages (27-300 V) at some fixed temperatures in the r ange 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 o f current oscillations increases exponentially with the increase of va por pressure, when other experimental conditions remained the same. Th e 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 wi th 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 curre nt oscillations in this organometallic semiconductor. The results have been discussed.