Molecular Beam Epitaxy Growth of Topological Insulator Quantum Dots for Applications in Quantum Technologies

Topological insulator (TI) quantum dots are highly promising for long wavelength quantum technological applications due to their topologically protected surface states in addition to the effect of quantum confinement. [1] We report the strained layer heteroepitaxial growth of the TI (Pb,Sn)Te quantum dots by molecular beam epitaxy on a CdTe buffer layer. Morphological characterization by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy confirms the formation of quantum dots with an average diameter of 30 nm while elemental mapping by energy dispersive X-ray spectroscopy shows the successful incorporation of Sn into PbTe quantum dots. The successful synthesis of Sn incorporated quantum dots even at this size would allow us to achieve an inter-level separation close to 100 meV in the mid-infrared. This offers a pathway to a promising quantum material with tunable electronic and optical properties relevant for long-wave to mid-infrared quantum sensors.

[1] M. Governale and F. Taddei, Topological-Insulator Nanocylinders, SciPost Phys. Core 6, 032 (2023).