Electrophoretic Light Scattering for Surface Zeta Potential Measurement of ALD Metal Oxide Films

The zeta potential and the isoelectrical points of ALD grown Al2O3, TiO2, and ZrO2 thin metal oxide films were measured by electrophoretic light scattering technique over a wide range of pH values. The magnitude of the zeta potential of the three ALD films decreases as the concentration of the KCl electrolyte increases, while the ZPC is almost the same for various electrolyte concentrations. The ALD Al2O3 film surface was found to have the highest magnitude in zeta potential in the important pH value range of 5.5 to 7. The zero point charge of alumina (Al2O3) has been measured to occur at pH values exceeding 8. In contrast, the zero point charge of titania (TiO2) occurred at a pH value of about 6.