Silicon oxide (SiO(x)) thin film was deposited onto fluorine-doped tin oxide (FTO) and silicon wafer substrate by the reduction of an aqueous solution containing ammonium hexafluorosilicate, dimethylamine borane and cetyltrimethylammonium bromide (CTAB). Characterization of the films by X-ray photoelectron spectroscopic depth profile and infrared spectroscopy proved that the addition of CTAB into the film enhanced the aggregation of silica particles and the growth rate. The SiO(x) films (resistivity: 3.2x10(8) Q cm) remarkably improved the rectification properties of FTO/SiO(x)/poly(3,4-ethylenedioxythiophene) derivative diodes. A rectification mechanism based on conduction of electron and ions was investigated. (C) 2008 Elsevier B.V. All rights reserved.