The organic/inorganic semiconductor heterojunction has been fabricated by thin film formed on n-Si semiconductor substrate using spin coating technique from the solution of polyaniline (PANI) titanium dioxide (TiO2) composite chemically synthesized in the presence of the cationic surfactant, tetradecyltrimethylammonium bromide (TTAB). The thickness of the polymeric film coated on the n-Si substrate has been found to be 110 nm by using the profilometer. The current-voltage (I-V) characteristics of the PANI TiO2 TTAB/n-Si heterojunction have been measured in the temperature of 178-238K. The I-V characteristics of the PANI TiO2 ITAB/n-Si heterojunction have shown the rectifying behavior. The forward I-Vcharacteristics of the device have been analyzed on the basis of the standard thermionic emission (TE) theory. An abnormal increase in the barrier height and decrease in the ideality factor with increasing temperatures has been shown. This behavior has been interpreted assuming inhomogeneity of barrier formed at the interface. The temperature-dependent I-V characteristics of the PANI TiO2 TTAB/n-Si heterojuncdon have revealed a double Gaussian distribution giving mean barrier heights of 0.916 eV and 1.164 eV and standard deviations of 0.114 eV and 0.131 eV, respectively. Furthermore, the PANI TiO2 TTAB has been characterized by using Fourier Transform Infrared (FTIR), Ultraviolet-visible (UV-vis) spectra and X-ray diffraction analysis (XRD). (C) 2011 Elsevier B.V. All rights reserved.