The current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of Al/aniline green(AG)/n-Si/AuSb structure were investigated at room temperature. A modified Norde's function combined with conventional forward I-V method was used to extract the parameters including barrier height (BH) and the series resistance. The barrier height and series resistance obtained from Norde's function was compared with those from Cheung functions, and it was seen that there was a good agreement between the BH values and series resistances from both methods. The C-V characteristics were performed at 10 and 500 kHz frequencies, and C-f characteristics were performed 0.0, +0.4 and -0.4V. (C) 2008 Elsevier Ltd. All rights reserved.