A Study of the Optimal Process Conditions of AZO:H 2 Thin Film for Maximization of the Transmittance of a Blue GaN Light-Emitting Diode with a Wavelength of 470 nm

This study has been carried out to determine the optimal process conditions of AZO:H2 thin films for the maximization of the transmittance of a blue GaN light-emitting diode (LED) with a wavelength of 470 nm. The Al-doped zinc oxide (AZO):H2 thin films were deposited on a sapphire substrate by radio-frequency magnetron sputtering system with varying substrate temperatures, working pressures and annealing temperatures temperature, working pressure and annealing imposed on a AZO (2wt% Al2O3) ceramic target. The effect of these variables was investigated in order to improve the light extraction efficiency of the LED. As a result, the (002)-oriented peak was found in all the AZO:H2 thin films. The lowest resistivity and the best transmittance at a wavelength of 470 nm was found to be 4.774 × 10(-4) Ωcm and 92% at a substrate temperature of 500˚C, working pressure of 7 mTorr and annealing temperature of 400˚C. The transmittance of the AZO:H2 thin film for the Blue GaN LED was improved by approximately 13% relative to that of a ITO thin film (T = 79%).