Strain engineering of self-organized InAs quantum dots

The effects of a thin gallium-rich ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ cap layer on the electronic properties of self-organized InAs quantum dots (QD’s) are investigated both experimentally and theoretically. Increasing the indium concentration of the cap layer allows tuning the ground state transition to lower energies maintaining strong quantization of the electronic states. Strain-driven partial decomposition of the ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ cap layer increases the effective QD size during growth and the altered barrier composition leads to a partial strain relaxation within the capped InAs QD’s. Strain engineering the structural properties of the QD’s as well as the actual confining potential offers a pathway to control the electronic properties, e.g., to shift the emission wavelength of lasers based on self-organized InAs QD’s to the infrared.