Self-assembled InAsSb quantum dots grown on GaAs substrates by molecular-beam epitaxy

To achieve long-wavelength emissions from quantum structures grown on GaAs substrates, InAsSb quantum dots were grown using two methods and compared. The first was conventional molecular-beam epitaxy in which arsenic and antimony were irradiated at the same time. In the second, antimony flux was irradiated after the InAs quantum dots were grown to prevent the flux from working as a surfactant. Clear and sharp emissions around 1.3 μm were observed at 77 K from InAsSb quantum dots grown with the second method. However, the photoluminescence spectrum from conventional InAsSb alloy split into two peaks. This was probably due to size fluctuations in the InAsSb quantum dots. This indicates that antimony irradiation after InAs quantum dots are grown is a suitable technique to grow long-wavelength InAsSb dots while maintaining dot uniformity.