Temperature-dependence of exciton radiative recombination in (Al,Ga)N/GaN quantum wells grown on a-plane GaN substrates

This article presents the dynamics of excitons in a-plane (Al,Ga)N/GaN single quantum wells of various thicknesses grown on bulk GaN substrates. For all quantum well samples, recombination is observed to be predominantly radiative in the low-temperature range. At higher temperatures, the escape of charge carriers from the quantum well to the (Al,Ga)N barriers is accompanied by a reduction in internal quantum efficiency. Based on the temperature-dependence of time-resolved photoluminescence experiments, we also show how the local disorder affects the exciton radiative lifetime at low temperature and the exciton non-radiative lifetime at high temperature.We acknowledge financial support from the Swiss National Science Foundation through Project No. 129715 and from the Polish National Science Center (Project DEC-2011/ 03/B/ST3/02647). The work was partially supported by the European Union within European Regional Development Fund through Innovative Economy Grant No. POIG.01.01.02-00-008/08. P.C. also acknowledges financing from the European Union Seventh Framework Program under grant agreement No. 265073

GROWTH AND CHARACTERIZATION OF GAALAS GAAS AND GAINAS INP STRUCTURES - THE EFFECT OF A PULSE METALORGANIC FLOW

GaAlAs/GaAs and GaInAs/InP thick layers, single and multiple quantum wells were grown by atmospheric pressure metalorganic vapor phase epitaxy. Auger electron spectroscopy, wedge transmission electron microscopy, x-ray diffraction, low-temperature photoluminescence, and scanning electron microscopy were used to analyze the crystal quality. These analysis techniques show that layers grown using high vapor pressure metalorganic sources present fluctuations in the ternary alloy composition. We propose that these fluctuations are due to the pulse character of the high vapor pressure metalorganic flow. Bubbling experiments were performed to show the relationship between ternary layer composition fluctuation and the pulse character of the metalorganic flow. High vapor pressure metalorganic source like trimethylgallium presents tens of Angstroms growth rate per pulse or bubble whereas a low vapor pressure source like triethylgallium presents few Angstroms growth rate per bubble.71117918

ZnSe growth on lattice-matched InxGa1-xAs substrates

The properties of ZnSe epilayers fabricated by molecular beam epitaxy on lattice-matched InxGa1-xAs buffers grown on GaAs(001) substrates have been investigated by means of photoluminescence spectroscopy and transmission electron microscopy. For suitable values of x and ternary-layer thickness, the partial character of the strain relaxation within the III-V layer can be compensated for, minimizing the residual strain in the ZnSe overlayer. Large reductions in the dislocation density and Y-line emission as compared to conventional ZnSe/GaAs heterostructures can be reproducibly obtained