Strong Light-Extraction Enhancement of GaN-Based Light-Emitting Diodes with Top and Sidewall GaOOH Nanorod Arrays

We reported the gallium nitride-based blue light-emitting diodes (LEDs) with top and sidewall gallium oxide hydroxide (GaOOH) nanorod arrays (NRAs). Highly-oriented GaOOH NRAs were formed on the surfaces of LEDs by the electrochemical deposition method using a sputtered tin oxide seed layer. The as-synthesized GaOOH NRAs exhibited a high light-scattering property while maintaining high transparency of >90% in the visible wavelength range. For LEDs with top and sidewall GaOOH NRAs, the light output power was significantly enhanced by similar to 36% and the far-field radiation pattern also became wider compared to the conventional LED. This improvement in light extraction is attributed to the relatively graded refractive index profile and the formation of roughened top and sidewall surfaces by the GaOOH NRAs. (C) 2012 The Japan Society of Applied Physics