Realization of Stranski–Krastanow InAs quantum dots on nanowire-based InGaAs nanoshells

Abstract

We investigate the formation and optical properties of InAs quantum dots on an InGaAs nanosubstrate. We find that Stranski–Krastanow InAs quantum dots are hardly formed on Au-catalyzed InGaAs nanowires due to the phase separation as well as stacking faults. High-quality Stranski–Krastanow InAs quantum dots are realized on a pure zinc blende InGaAs shell radially grown on a GaAs nanowire core. The quantum dots have a large size and regular shape, residing on a wetting layer of several nanometers. For optical characterization, we fabricate a “dot-in-well” structure by capping the quantum dots with InGaAs/GaAs double layers. Photoluminescence from the quantum dots is observed at 77 K, with a peak wavelength of 954 nm, which is distinctly redshifted compared with that of InAs quantum dots directly grown on GaAs nanowires. This work shows the potential of growing Stranski–Krastanow QDs on more types of NWs and obtaining longer wavelengths for wider applications.