Epitaxial quantum dots with symmetric and highly facetted shapes are fabricated by thermal annealing of two-dimensional (2D) PbTe epilayers embedded in a CdTe matrix. By varying the thickness of the initial 2D layers, the dot size can be effectively controlled between 5 and 25nm, and areal densities as high as 3×1011cm−2 can be achieved. The size control allows the tuning of the quantum dot luminescence over a wide spectral range between 2.2 and 3.7μm. As a result, ultrabroadband emission from a multilayered quantum dot stack is demonstrated, which is a precondition for the development of superluminescent diodes operating in the near infrared and midinfrared.

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This paper describes a selective growth of PbTe/CdTe quantum wells (QWs) and quantum dots (QDs) in CdTe host matrix by molecular beam epitaxy. These two tellurides possess almost identical lattice constants, but differ fundamentally in their lattice structure. Owing to a strong phase separation by the lattice‐type mismatch, insertion of a PbTe thin layer in CdTe matrix at higher temperatures than 280 °C was resulted in a self‐organized growth of coherent and three‐dimensionally isotropic QDs. The same growth procedure at lower temperatures, on the other hand, yielded a conventional QW structure with sharp heterointerface. This QW structure, however, was found to precipitate well‐ordered QD‐array by a postgrowth annealing, indicating that the QD formation is induced by the minimization of interface energy between the inmiscible two tellurides. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)