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Interdiffusion in InGaAs/GaAs quantum wells has been studied using photoluminescence to follow the development of the diffusion with time in a single sample. Two distinct regimes are seen; a fast initial diffusion and a second steady-state diffusion. The steady-state diffusion was found to be dependent on the depth of the quantum well from the surface and to correlate with published data on the indiffusion of gallium vacancies into gallium arsenide.

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We have experimentally studied the photoluminescent ͑PL͒ properties of Si clusters in fused silica matrices. Si clusters in the SiO 2 matrices were fabricated by Si ϩ -ion implantation ͑200 keV, 2ϫ10 17 cm Ϫ2 ͒ into silica and then thermally annealed in forming gas. A broad PL peak is observed in the visible spectral region at room temperature. The temperature dependence of the luminescent spectrum and the PL decay dynamics are controlled by nonradiative recombination processes due to phonon-assisted tunneling between localized radiative and nonradiative centers. Resonantly excited PL spectra indicate that the strong coupling of excitons and stretching vibrations of the Si-O bonds cause fine structures in the luminescent spectra. It is concluded that the interaction between electronic and vibrational excitations control the luminescent emission and the observed dynamics.