Investigation of Morphology of InSb/InAs Quantum Nano-Stripe Grown by Molecular Beam Epitaxy

InSb/InAs quantum nanostructures show many promising properties towards mid-infrared optical applications due to their type-II energy band alignment with a broken gap. Dimension and morphology of the quantum nanostructures are keys to extending an emission wavelength to a longer wavelength range due to the quantum effect. The effect of the number of InSb monolayers on dimension and morphology of InSb/InAs quantum nanostructures grown by using molecular beam epitaxy is then investigated in this work. The InSb/InAs quantum nano-stripes with elongation along [110] direction are grown on an InAs substrate by using low growth temperature and slow growth rate. Samples with different numbers of InSb monolayers when growing InSb/InAs quantum nano-stripes, i.e. 2, 3, 4 and 5 monolayers, are prepared. The dimension and morphology of InSb/InAs quantum nano-stripes are characterized by using atomic force microscopy. With increasing number of InSb monolayers, the formation of the InSb/InAs quantum nanostructures is dominated by the lateral growth. The quantum nano-stripes start to merge with each other as the number of InSb monolayers increases, resulting in the limitation in the dimension of the InSb/InAs quantum nano-stripes in the sample with 5 monolayers. We postulate that this is due to the usage of low growth temperature.