Properties of TiO2-based transparent conducting oxide thin films on GaN(0001) surfaces

Anatase Nb-doped TiO2 transparent conducting oxide has been formed on GaN(0001) surfaces using a sputtering method. Amorphous films deposited at room temperature were annealed at a substrate temperature of 500 degrees C in vacuum to form single-phase anatase films. Films with a thickness of 170 nm exhibited a resistivity of 8 X 10(-4) Omega cm with absorptance less than 5% at a wavelength of 460 nm. Furthermore, the refractive index of the Nb-doped TiO2 was well matched to that of GaN. These findings indicate that Nb-doped TiO2 is a promising material for use as transparent electrodes in GaN-based light emitting diodes (LEDs), particularly since reflection at the electrode/GaN boundary can be suppressed, enhancing the external quantum efficiency of blue LEDs. (C) 2010 American Institute of Physics. [doi:10.1063/1.3326943]