A photoelectron spectroscopy study on the indium tin oxide treatment by acids and bases

We report on the chemical adsorption of acids and bases on indium tin oxide (ITO). Ultraviolet photoelectron spectroscopy was used to measure the work function of the treated ITO and atomic surface concentrations were determi ned by x-ray photoelectron spectroscopy. The acid treatments yield work-fun ction shifts as high as 0.7 eV compared to the nontreated ITO. Huge shifts in the work function are also obtained for the treatments with bases and ar e opposite to those obtained with the acids. These dramatic shifts are indi cative of a double ionic surface layer. The importance of an appropriate pl asma treatment prior to the chemical adsorption of acids or bases is discus sed in terms of surface acido-basicity. (C) 1999 American Institute of Phys ics. [S0003-6951(99)00506-9].