Correlation of Optical, Structural and Compositional Properties with V-Pit Distribution in InGaN/GaN Multi-Quantum Wells.

InGaN/GaN double heterostructures and multi-quantum wells have been successfully developed since more than 20 years for LED lightning applications. Recent developments show that state-of-the-art LEDs benefit from artificially generated V-pit defects. However, the control of structural and chemical properties plays a tremendous role. In this paper we report on the lateral distribution of V-pit defects and photoluminescence of InGaN/GaN multi quantum wells grown on thick GaN on patterned sapphire substrates. The synchrotron based scanning x-ray diffraction microscopy technique K-Map was employed to locally correlate these properties with the local tilt, strain and composition of the InGaN/GaN multi-quantum well. Compositional fluctuation is the main factor for the variation of photoluminescence intensity and broadening. In turn V-pit defects, align along small-angle grain boundaries, and their strain fields are identified as reason for promoting the InGaN segregation process on a microscale.