Effects of Film Thickness and Annealing Temperature on the Specific Contact Resistivity and the Transmittance of the IZO Layers Grown on p-GaN by Roll-to-Roll Sputtering

We report on the characteristics of indium-oxide-doped ZnO (IZO) ohmic contact to p-GaN. The IZO ohmic contact layer was deposited on p-GaN by a Roll-to-Roll (RTR) sputter method. IZO contact film with a thickness of 360, 230 and 100 nm yielded an ohmic contact resistance of 4.70x10(-4), 5.95x10(-2), 4.85x10(-1) Omega cm(2) on p-GaN when annealed at 600 degrees C for 1 min under a nitrogen ambient, respectively. While the transmittance of IZO film with a thickness of 360 nm slightly increased in the wavelength range of 380-800 nm after annealing, the transmittance rapidly increased up to 80% after annealing at 600 degrees C in the wavelength range of 380 similar to 430 nm because the crystallization of IZO film and created Ga vacancies near the p-GaN surface region were affected by the annealing. These results indicate that ohmic contact resistance and transmittance of the IZO films improved.