Properties of nonpolar a-plane InGaN∕GaN multiple quantum wells grown on lateral epitaxially overgrown a-plane GaN

The properties of nonpolar $a$ -plane InGaN∕GaN multiple-quantum wells (MQWs), grown simultaneously on lateral epitaxially overgrown (LEO) $a$ -plane GaN and planar $a$ -plane GaN, were studied. High-resolution x-ray diffraction analysis revealed that the In mol fraction in the MQWs grown on LEO-GaN was significantly lower than that on planar $a$ -plane GaN. The lower In incorporation was confirmed by microphotoluminescence (μ-PL) and wide-area photoluminescence measurements, which showed a redshift of the MQW emission from 413 nm for the nearly defect-free laterally overgrown regions to 453 nm for the defective “window” regions of the LEO $a$ -plane GaN, to 478 nm for the high-defect density planar $a$ -plane GaN. μ-PL measurements also demonstrated that the emission from the nearly defect-free wings of the LEO $a$ -plane GaN was more than ten times stronger than the emission from the defective windows.