Fabrication of Nonpolar a-Plane Nitride-Based Solar Cell on r-Plane Sapphire Substrate

We fabricated and characterized a nonpolar a-plane nitride-based solar cell on an r-plane sapphire substrate. The maximum external quantum efficiency of the solar cell reached 62% at a wavelength of approximately 400 nm. The open-circuit voltage, the short-circuit current density, and the fill factor of the solar cell were 0.9 V, 4.8 mA/cm2, and 57%, respectively. A conversion efficiency of 1.6% was obtained from the solar cell under a solar simulator of air mass 1.5 G and an irradiation intensity of 155 mW/cm2 at room temperature.