Aluminum phthalocyanine chloride (AlClPc) thin films were evaporated and the properties of the AlClPc thin films treated with ethanol vapor were investigated using attenuated total reflection (ATR) and emission light measurements due to surface plasmon (SP) excitations. The optical absorption spectra and surface morphology remarkably changed due to the ethanol-vapor treatment. From the ATR measurement, it was found that the thickness evaluated from the theoretical calculations increases with the treatment of ethanol vapor. The emission lights due to SP were also observed for the samples. The emission light intensity increase with the surface roughness for the incident light with wavelength of 488.0 nm. The current vs. voltage characteristics of the AlClPc thin films before and after the ethanol-vapor treatment were also investigated and it was found that the conduction current was increased by the ethanol-vapor treatment. (c) 2005 Elsevier B.V. All rights reserved.