Demonstration of nonpolar a -plane InGaN/GaN light emitting diode on r -plane sapphire substrate

High crystalline a-plane (112̄0) GaN epitaxial layers with smooth surface morphology were grown on r -plane (11ō0) sapphire substrate by metalorganic chemical vapor deposition. The full width at half maximum of x-ray rocking curve was measured as 407 arc sec along c -axis direction, and the root mean square roughness was 1.23 nm. Nonpolar a -plane InGaN/GaN light emitting diodes were subsequently grown on a -plane GaN template, and the optical output power of 0.72 mW was obtained at drive current of 20 mA (3.36 V) and 2.84 mW at 100 mA (4.62 V) with the peak emission wavelength of 477 nm.