We report the formation of self-assembling CdSe quantum dots during molecular beam epitaxial growth on ZnSe and ZnMnSe. Atomic force microscopy measurements on specimens with uncapped dots show relatively narrow dot size distributions, with typical dot diameters of 40±5 nm, and with a diameter-to-height ratio consistently very close to 4:1. Uncapped CdSe dots are unstable with time: their density was observed to drop by an order of magnitude in 10 days, with clear evidence of ripening observed for some dots. Photoluminescence from capped dots indicates exciton localization much stronger than in ZnCdSe/ZnSe quantum wells, due to the additional lateral confinement.

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p-type doping of molecular beam epitaxy grown GaSb by Ge and Sn has been demonstrated. Both impurities are well behaved with demonstrated free acceptor concentrations as high as 2×1019 cm−3 for Ge and 5×1018 cm−3 for Sn. In addition reflection high-energy electron diffraction measurements during growth indicate that Sn segregation which is common in GaAs does not occur in GaSb. The absence of Sn segregation as well as the p-type nature of Ge and Sn dopants is attributed to the large covalent bond radius of Sb. These dopants are important since they provide an excellent alternative to Be for p-type doping of Sb based materials.

It is shown that the unique properties of strained-layer quantum well lasers can be identified by measuring the relaxation oscillation frequency as a function of optical gain. These measurements are insensitive to effects due to nonradiative recombinations and leakage currents, which can mask the beneficial effects in terms of a lower threshold current due to a reduced hole mass in strained quantum wells. The conclusion, both theoretically and experimentally, is that strained-layer quantum well lasers have a higher differential gain but saturate at a lower gain level as compared to regular quantum well lasers. As a consequence, for a strained single quantum well, slightly higher relaxation oscillation frequency results, but only for certain limited ranges of device parameters. A multiple strained-layer quantum well can in theory take better advantage of the higher differential gain.