Growth-related photoluminescence properties of InSb/GaAs self-assembled quantum dots grown on (001) Ge substrates

Highlights: • Self-assembled InSb/GaAs QDs on anti-phase-domain-decorated Ge substrate are grown by molecular beam epitaxy. • The QD size, shape, density and positioning are controlled by the various growth conditions. • The effect of QD morphologies on the photoluminescence emission is revealed by various PL spectroscopies. • The type-II band alignment and shape anisotropy are revealed by PL spectroscopies. Various photoluminescence (PL) spectroscopies are applied to reveal the growth-related properties of self-assembled InSb/GaAs quantum dots (QDs) grown on (001) Ge substrate. Obtained QDs have rectangular-based shape and mainly locate near GaAs antiphase domain boundaries (APBs), which are formed during the growth of GaAs on (001) Ge substrate. The morphology and structural properties of InSb QDs can be varied by the change of controlled growth conditions. Optical phonons scatterings of the embedded InSb QDs are revealed by Raman spectroscopy. The low-temperature PL emission energy of InSb/GaAs QDs is in the range of 1.18–1.29 eV. The power-dependent PL spectroscopy confirms the type-II band alignment in this system. The thermal activation energies (22.7 meV and 146.5 meV) are extracted from the temperature-dependent PL spectroscopy (10–140 K). The polarization-dependent PL spectroscopy is performed and exhibits the polarization degree of ~ 18%, which is attributed to the shape anisotropy of buried InSb QDs.