Ge microcrystals embedded in SiOZ glassy matrices were formed by a radio-frequency magnetron cosputtering technique and then annealed at 800 "C for 30 min. The average radius of the Ge microcrystals in SiOZ was determined to be about 3 nm by means of Raman spectroscopy and high resolution electron microscope. The annealed sample showed a strong room temperature luminescence with a peak at 2.18 eV. This is consistent with quantum confinement of electrons and holes.

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Strain relaxation in stripe-shaped GaAs layers on Si(100) substrates by post-growth patterning has been investigated by photoluminescence (PL) measurements. PL spectrum for the GaAs stripes along [001] showed peaks positioned at shorter wavelength than those for stripes along [011] and [01̄1]. The stripe-orientation dependence was regarded as the crystallographic anisotropy of strain relaxation in the stripe-shaped GaAs layers. The PL results, therefore, showed that the stripes along [001] were superior to those along [011] and [01̄1] for reducing residual strain in the GaAs layers.