Excitonic luminescence from self-organized quantum dots of CdTe grown by molecular beam epitaxy

Self-organized quantum dots (QDs) of CdTe were successfully grown on a ZnTe (100) surface by molecular beam epitaxy. Atomic force microscopy measurements of 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 when a 3.5 monolayer-thick CdTe was deposited. In the photoluminescence (PL) measurements of the capped QDs, an intensive excitonic luminescence was observed at 4.2 K, the intensity of which was higher than the CdTe/ZnTe single quantum wells (SQWs) by 2-4 orders of magnitude. The temperature dependence of the intensity showed thermal quenching with an activation energy of 110 meV, which was about twice as large as those of SQWs. The PL dt fay time in QDs exhibited a different temperature dependence from SQWs - a temperature-independent decay time below 20 K. These results are interpreted as features of zero-dimensional confinement of excitons in QDs.