Optical properties of single InGaN quantum dots and their devices

Abstract

AbstractNitride‐based quantum dots have many attractive optical properties for the realization of quantum dot (QD) based devices which will be presented in this contribution. We will analyze the basic characteristics of single InGaN QDs and their electroluminescence (EL) as well as the optical properties of QD stacks and their gain spectra. The single QDs are characterized by the high temperature stability of their emission up to 150 K in PL and EL and even up to room temperature for stacked QD samples. Furthermore, the polarization of individual QD emission lines was analyzed giving an insight into their geometrical shape. Time‐resolved microphotoluminescence (µ‐PL) measurements on the excitonic and biexcitonic transition of a single QD as well as on the influence of piezoelectric fields on them and on their binding energy were performed. Further, we present an analysis of electrically driven luminescence from single InGaN QDs embedded into a light emitting diode structure showing single sharp emission lines in the green spectral region with a high temperature stability up to 150 K. Furthermore, for the possible integration within optical devices in the future the threshold power density as well as the modal gain were investigated for samples with stacked InGaN QD layers. They show a modal gain per QD being comparable to that of II–VI and III‐As compounds. These results give a good insight into the basic optical properties of InGaN QD based devices and showing their high potential for electrically driven single photon emitters as well as for bright, low‐threshold InGaN QD based light emitting devices in the near future.