3 research outputs found
Recent advances in exciton based quantum information processing in quantum dot nanostructures
Recent experimental developments in the field of semiconductor quantum dot
spectroscopy will be discussed. First we report about single quantum dot
exciton two-level systems and their coherent properties in terms of single
qubit manipulations. In the second part we report on coherent quantum coupling
in a prototype "two-qubit" system consisting of a vertically stacked pair of
quantum dots. The interaction can be tuned in such quantum dot molecule devices
using an applied voltage as external parameter.Comment: 37 pages, 15 figures, submitted to New Journal of Physics, focus
issue on Solid State Quantum Information, added reference
Towards quantification of the crucial Impact of auger recombination for the Efficiency droop in (AlInGa)N Quantum well structures
Recent experimental investigations on the reduction of internal quantum efficiency with increasing current density in (AlInGa)N quantum well structures show that Auger recombination is a significant contributor to the so-called "droop" phenomenon. Using photoluminescence (PL) test structures, we find Auger processes are responsible for at least 15 % of the measured efficiency droop. Furthermore, we confirm that electron-electron-hole (nnp) is stronger than electron-hole-hole (npp) Auger recombination in standard LEDs. The ratio of respective Auger coefficients is determined to be in the range 1 < C-nnp = C-npp <= 12. This asymmetry is shown to limit the detection efficiency of Auger processes in our PL-based approach. (C) 2016 Optical Society of Americ