Characteristics of Thermally Oxidized-Ti as a High-k Gate Dielectric on SiC Metal-Oxide-Semiconductor Devices

Abstract

We have investigated the structural and electrical properties of thermally oxidized-Ti gate dielectric stacks on 4H-SiC films. In addition, SiO2 films were used as an interfacial layer between TiO2 films and 4H-SiC substrate. The TiO2 films were grown by oxidising evaporated Ti films at the temperature range of 700-1000 ºC for 1 hour. The films remain amorphous up to oxidation temperature of 900 ºC while oxidation at 1000 ºC transforms the film to be polycrystalline. X-ray photoelectron spectroscopy confirms the formation of stoichiometric TiO2 films. Capacitance-voltage characteristics exhibit the shift of flatband voltage attributing the presence of oxide charges. The TiO2/SiO2 4H-SiC capacitors in which Ti was oxidized at 800 ºC give the less fixed oxide charge density with moderate value of interface state density and less leakage current density.