INFLUENCE OF A PARALLEL ELECTRIC-FIELD ON THE CONDUCTIVITY OF A GROWING INDIUM OXIDE FILM

Thin films of amorphous InO were produced by thermal vapor deposition of InO powder in vacuum (P = 10(-5) Torr) at room temperature onto gla ss substrates. A potential difference in the range of 0-110 V DC was a pplied to the sample during deposition. The effect of the applied volt age on the him conductivity was monitored by the current through the h im. The him mass increase was linearly proportional to the deposition time (5-6 min). A non-linear increase of the current of several orders of magnitude was observed. The film resistance was measured in the ra nge 100-10(8) Omega. To explain the experimental data it was hypothesi zed that when the voltage across the sample is applied tunneling and p ercolation are responsible for the growing film conductivity. The vari ation of the characteristic parameters of tunneling and percolative co nductance with the applied voltage were derived by fitting the depende nce of the current on the voltage with analytical expressions correspo nding to tunneling conductance al the initial phase of the coating pro cess, followed by percolative conductance. It was found that the trans ition from tunneling conductance to percolative conductance takes plac e at earlier times as a function of the applied voltage, and that the critical percolation exponent increases with the applied voltage.