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We report on optical properties of CdTe self-assembled quantum dots ͑SADs͒ grown by molecular beam epitaxy on ZnTe. Formation of SADs was achieved by deposition of 1.5-2.5 monolayers of CdTe at a substrate temperature of 420°C and by applying growth interrupts for few seconds in Cd flux. The resulting dots have a typical diameter of 2 nm and a sheet density of 10 12 cm Ϫ2 . At Tϭ2 K the photoluminescence ͑PL͒ spectra consist of two emission lines. The high-energy line originates from excitonic recombination in a wetting layer while the low-energy emission PL band is assigned to recombination in SADs. The increase in temperature up to 70 K does not affect the SADs-related emission intensity. It shifts, however, the PL peak energy towards low energies and causes a significant narrowing of the PL linewidth, from 80 meV at 1.9 K to 50 meV at 130 K. The activation energy of the thermal quenching of SADs-related PL emission was found to be equal to 47 meV. This value is three times greater than the one observed in CdTe/ZnTe quantum wells, that is, 12-17 meV.

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We present a comprehensive study of the reversal process of perpendicular magnetization in thin layers of the ferromagnetic semiconductor Ga 1-x Mn x As. For this investigation we have purposely chosen Ga 1-x Mn x As with a low Mn concentration (x ≈ 0.02), since in such specimens contributions of cubic and uniaxial anisotropy parameters are comparable, allowing us to identify the role of both types of anisotropy in the magnetic reversal process. As a first step we have systematically mapped out the angular dependence of ferromagnetic resonance in thin Ga 1-x Mn x As layers, which is a highly