Growth habits of bismuth selenide (bi₂se₃) layers and nanowires over stranski-krastanov indium arsenide quantum dots

Bismuth selenide layers and nanowires have been grown by molecular beam epitaxy on self-Assembled Stranski-Krastanov InAs quantum dots of different sizes and densities on GaAs substrates. The size and density of the InAs quantum dots were modified by changes in the growth rate and composition. The structure and growth habits of the Bi₂Se₃ layers were studied by high-resolution X-ray diffraction, scanning probe microscopy, energy-dispersive X-ray spectroscopy, and high-resolution electron microscopy. The epitaxial growth of continuous layers of (0001) Bi₂Se₃ was observed over flat InAs surfaces. In contrast, the presence of InAs quantum dots induced the growth of 100 nm long and 20 nm wide Bi₂Se₃ nanowires primarily oriented along the [01-1] and [0-1-1] directions. The nanowires coalesced into full layers when the growth proceeded further. A better understanding and control of the Bi₂Se₃ growth habits over these surfaces should lead to novel nanostructures with enhanced physical properties.