Size control and midinfrared emission of epitaxial PbTe/CdTe quantum dot precipitates grown by molecular beam epitaxy

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 25 nm, and areal densities as high as 3x10(11) cm(-2) can be achieved. The size control allows the tuning of the quantum dot luminescence over a wide spectral range between 2.2 and 3.7 mu m. 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. (C) 2007 American Institute of Physics.