Titanium dioxide thin films were deposited on thermally oxidized silicon wafers by metal organic CVD (MOCVD). Then the resulting TiO2/SiO2/Si test structures were annealed in dry oxygen for 60 min at temperatures 700, 800, 900, and 1000 degreesC, respectively. Refractive index and relative permittivity of the as-deposited and annealed titanium dioxide layers were investigated by spectral ellipsometry and high frequency capacitance-voltage (HF-CV) measurements. The pH-sensing properties of the titanium dioxide layers were investigated by capacitance-voltage measurements on electrolyte/insulator/silicon (EIS) structures. In addition, light-induced drift of the test structures was investigated by illumination using 12 V light bulb for 60 min in a measurement chamber. The titanium dioxide layers revealed refractive index of 2.38-2.58 (lambda = 550 nm) and relative permittivity of 31.28-36.27. Integral pH-sensitivities (pH ranging from 3 to 11) of the titanium dioxide layers were 57.4-62.3 mV/pH (T = 32 degreesC). All the titanium dioxide layers showed no light-induced drift. After long-term measurement, the titanium dioxide layer annealed at 900 degreesC revealed a better stability of the pH-sensing properties than other titanium dioxide layers investigated in this study. (C) 2003 Elsevier Science B.V. All rights reserved.