The Cavity-Effect in Site-Controlled GaN Nanocolumns with InGaN Insertions

Abstract

We have studied optical properties of site-controlled GaN nanocolumns (NCs) with an insertion of InGaN QW grown on the micro-cone patterned substrate. Time-resolved photoluminescence spectroscopy reveals two bands emission. Comparison of these spectra with the emission of a separate nanocolumn, recorded by μ-CL with high spatial resolution, allows us to ascribe the higher energy band to emission from the InGaN QW situated on the top of NCs, while the lower-energy band originates from the QW in the rest area. By the modeling of the decay times and amplitudes of PL decay curves, we have exhibited a significant enhancement of signal from the QW inside the NCs. Investigation of the NCs as a Fabry-Perot cavity at eigenfrequencies around the optical transitions has revealed that the cavity modes can provide significant enhancement of the emission from the inserted QW owing to the Purcell factor.