The successful growth of self-organized quantum dots (QDs) of CdTe on ZnTe (100) surface by molecular beam epitaxy is reported. Atomic force microscope measurements on the uncapped samples revealed the formation of CdTe QDs with typical dot diameters of 20±2 nm and heights of 2.7±0.3 nm at 3.5-ML-thick CdTe deposited. The intensity of photoluminescence (PL) from the capped QDs was higher than CdTe/ZnTe single quantum wells (SQWs) by a few orders of magnitude at 4.2 K, and exhibited a thermal quenching with an activation energy of 110 meV, which is about twice as large as those in SQWs. In time-resolved PL measurements, the decay time was almost independent of temperature below 20 K. This is interpreted as due to the zero-dimensional excitonic properties in QDs.
Abstract.The correlation between Cr spatial distribution and magnetic properties have been investigated for Zn1-xCrxTe films with low and high average Cr contents of x ≅ 0.05 and 0.2, which were grown by MBE under different Zn/Te flux or with the co-doping of donor impurity iodine. The EDS analysis reveals that the Cr distribution is strongly inhomogeneous in films grown under the Zn-rich condition or co-doped with iodine, in contrast to relatively homogeneous distribution in undoped films grown in the Te-rich condition. In the magnetization measurements, the superparamagnetic features, such as the blocking phenomena in the temperature dependence of magnetization, become more pronounced with the enhancement of inhomogeneity of Cr distribution.
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