Luminescence redshift of thick InGaN/GaN heterostructures induced by the migration of surface adsorbed atoms

Abstract Nitride heterostructures with an extremely high number of InGaN/GaN multiple quantum wells (MQWs) were grown and studied by multiple techniques. Large redshift (282 meV) in photoluminescence (PL) spectra was observed with an increasing number of quantum wells (QWs) in the structure from 10 to 60. From the comparison of structures grown on sapphire and GaN substrates, the phenomenon of giant redshift is explained. A theory based on the surface migration of the adsorbed atoms from the semi-polar V-pit facets to the c-plane facets is suggested and proven by several experimental techniques including scanning transmission electron microscopy (STEM), secondary ion-mass spectroscopy (SIMS), secondary electron microscopy (SEM), white light interferometry (WLI), and spectrally and spatially resolved cathodoluminescence (SSRCL). Finally, a change in the surface morphology caused by the growing size of the V-pits and the transformation of the c-plane surface areas is discussed.