Carrier capture processes in strain-induced InxGa1-xAs/GaAs quantum dot structures

We investigate carrier capture processes in strain-induced quantum dot structures. The quantum dots consist of a near-surface InGaAs/GaAs quantum well in which a lateral confining potential is generated by the strain from InP stressor islands grown on the sample surface. Using photoluminescence spectroscopy, we show that the rate of carrier capture into the quantum dots increases dramatically when the energetic depth of the confinement potential is reduced by enlarging the quantum well/surface separation D. While carriers in the quantum well region between the quantum dots are found to experience D-dependent nonradiative surface recombination, this process seems to be negligible for carriers in the quantum dots, presumably due to the protecting InP islands.Peer reviewe

Magnetic moment measurements in the semi-magic nuclei 94^{94}Ru and 95^{95}Rh after recoil implantation into iron and nickel

The magnetic moments of the 12$^+$ and 11$^-$ yrast states in $^{94}$Ru and of the 25/2$^-$, 29/2$^+$, and 35/2$^+$ levels in $^{95}$Rh have been measured via the IMPAD technique. The nuclei were produced in the reaction $^{58}$Ni + $^{40}$Ca and recoil-implanted into polarized Ni and Fe hosts. The g-factors were deduced from the measured time-integral Larmor precessions. The comparison between the experimental results and large-scale shell model calculations suggests that the 12$^+$ and $11^-$ states in $^{94}$Ru and the 25/2$^-$ level in $^{95}$Rh are pure proton states whereas the 29/2$^+$ and 35/2$^+$ states in $^{95}$Rh contain a neutron excitation across the N=50 shell gap. This interpretation supports the conclusion drawn from recent lifetime measurements