Surface modification studies of ITO using atomic force microscopy and X-ray photoelectron spectroscopy

Surface modification was carried out on indium-tin oxide(ITO) thin films by means of oxygen plasma(OP) treatment.The effects of OP treatment on the surface properties of ITO thin films were investigated by Xray photoelectron spectroscopy(XPS),atomic force microscopy(AFM),and four-point probe techniques.Experimental results show that the OP treatment removes the hydrocarbon contaminant from the ITO surfaces,decreases the surface roughness and sheet resistance,optimizes the surface stoichiometry and improves the surface morphology.Chemical composition of the OP-treated surfaces was then monitored as a function of time elapsed after treatment and quantified.It is observed that the improved chemical composition tended to decay with the increment of time.Furthermore,the organic electroluminescent devices(OELDs) were fabricated using the treated and untreated ITO samples as hole-injecting electrodes,and the influence of surface properties of ITO electrodes on the performance of OELDs was studied with respect to the turn-on voltage,driving voltage,electroluminescent luminance and efficiency.