Electrical Conduction through SiO Films

Abstract

The voltage—current characteristics for evaporated SiO films sandwiched between Al electrodes is suggestive of the Schottky emission mechanism for film thickness between 1000 and 10 000 Å. The temperature dependence of the voltage—current characteristics and the photoresponse as a function of photon energy were measured to investigate the mechanism of current flow. The results show that the current density through the SiO film can be described by the following empirical equation: J=αa exp(βV12−γ/kT)[1−exp(−β2V)],where α and γ are constants and a is the SiO film thickness. The most important conclusion is that even though the functional form is similar to that which is obtained for the Schottky emission mechanism, the pre-exponential factor is not the Richardson constant times T2 and γ is not a barrier height corresponding to the threshold for photoresponse. The transient behavior of these films is suggestive of trapping and the resultant voltage—current characteristic may be due to space-charge buildup in the film as described by O'Dwyer.