Graded-composition quantum dots grown using liquid-phase epitaxy techniques in the In(As,Sb,P) material system cover the mid-infrared spectrum (wavelengths of 3 to 5 μm), which is important for a wide range of applications, e.g. in gas sensing or energy
harvesting. The particular strength of the growth process from the liquid phase is that
composition gradients through a nanostructure can be intentionally achieved, facilitating the fine-tuning of the optoelectronic properties together with a significant improvement of the crystal quality. In collaboration with researchers from PDI and IKZ Berlin as well as Prof. Karen M. Gambaryan from Yerevan State University, Armenia, we have investigated
nucleation process and electronic properties of In(As,Sb,P) graded-composition quantum dots in a systematic study, published recently in ACS Applied Electronic Materials.

We have computed the electronic properties for different heights and diameters, as
observed in the ensemble and combined these results with the experimentally observed diameter distribution to simulate ensemble absorption spectra at room temperature. The simulated absorption peak wavelength (3.829 μm) is in excellent agreement with the
experimentally observed one (3.83 μm), facilitating the application of our simulation framework in theory-driven design of In(As,Sb,P) graded-composition quantum dots that fulfill the requirements of specific devices.

This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – The Berlin Mathematics Research Center MATH+ (Project AA2-5). Prof. Gambaryan’s visit to WIAS Berlin was funded by Deutscher Akademischer Austauschdienst (DAAD).

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