Optical and electrical properties of titanium dioxide films with a high magnitude dielectric constant grown on <i>p</i>-Si by metalorganic chemical vapor deposition at low temperature

Abstract

Metalorganic chemical vapor deposition of titanium dioxide (TiO2) on p-Si(100) using titanium isopropoxide and nitrous oxide via pyrolysis at relatively low (∼500 °C) temperature was performed to produce high quality TiO2/p-Si interfaces and to fabricate TiO2 insulator gates with a dielectric constant of high magnitude. Scanning electron microscopy shows that the surfaces of the TiO2 films have very smooth morphologies. From the x-ray diffraction analysis, the grown layer was found to be a polycrystalline film. Raman spectroscopy showed the optical phonon modes of a TiO2 thin film. The stoichiometry of the TiO2 film was investigated by Auger electron spectroscopy. Room-temperature current-voltage and capacitance-voltage measurements clearly revealed metal-insulator-semiconductor behavior for the samples of the Ag/TiO2/p-Si. The interface state density at the TiO2/p-Si interface was approximately high 1011 eV−1 cm−2 at the middle of the Si energy gap, and the dielectric constant determined from the capacitance-voltage measurements was as large as 73. These results indicate the TiO2 layers grown at relatively low temperature can be used for high density dynamic memory.