Various misfit dislocations in green and yellow GaInN/GaN light emitting diodes

Abstract

Abstract We report the growth and structural characteristics of green and yellow (529–576 nm) GaInN/GaN light emitting diodes (LEDs) grown on two types of c ‐plane substrates – bulk GaN and sapphire. In this longer wavelength range, depending on the substrate, we find different strain relaxation mechanisms within the GaInN/GaN quantum well (QW) region. In optimized epitaxy, structures on sapphire that contain a low density of threading dislocations (TDs) within the n ‐GaN show virtually no generation of additional misfit dislocations (MDs) (<10 8 cm −2 ) or V ‐defects within the QW region for emission wavelengths up to 571 nm. On bulk GaN substrate, however, where much fewer TDs reach the QWs, strain relaxation is observed by inclined dislocation pairs in green emitters and a high density of edge‐type MDs in yellow emitters. The electroluminescence line width, as well as the efficiency droop, was found to increase with dislocation density in the QWs.