InAs self-assembled quantum dots grown on an InP (311)B substrate by molecular beam epitaxy

Self-assembled InAs quantum dots (QDs) have been grown by solid-source molecular beam epitaxy on a $\text{(311)B}$ InP substrate. Transmission electron microscopy clearly shows that a high density of smaller InAs islands can be obtained by using such a high index substrate. After introducing a lattice-matched underlying ${\mathrm{In}}_{\mathrm{0.52}}{\mathrm{Al}}_{\mathrm{0.24}}{\mathrm{Ga}}_{\mathrm{0.24}}\mathrm{As}$ layer, the InAs QDs are much more uniform in size and form two-dimensional well ordered arrays. The photoluminescence (PL) spectra also confirm that the InAs QDs grown on underlying ${\mathrm{In}}_{\mathrm{0.52}}{\mathrm{Al}}_{\mathrm{0.24}}{\mathrm{Ga}}_{\mathrm{0.24}}\mathrm{As}$ have a better quality than those grown in the ${\mathrm{In}}_{\mathrm{0.52}}{\mathrm{Al}}_{\mathrm{0.48}}\mathrm{As}$ matrix. A simple calculation indicates that the redshift of the PL peak energy mainly results from InAs QDs on underlying ${\mathrm{In}}_{\mathrm{0.52}}{\mathrm{Al}}_{\mathrm{0.24}}{\mathrm{Ga}}_{\mathrm{0.24}}\mathrm{As}$ of large size.