Growth of vertically self-organized InGaAs quantum dots with narrow inhomogeneous broadening

Abstract

We have fabricated vertically self-organized multiple sets of ${\mathrm{In}}_{\mathrm{0.6}}{\mathrm{Ga}}_{\mathrm{0.4}}\mathrm{As}$ quantum dots (QDs) on GaAs (001) that combines the concepts of variable amount deposition and shape stabilization and size equalization of QDs. The inhomogeneous broadening of optical emission from these dots reached a record low value of 18.4 meV at a wavelength of $\text{∼1185\hspace{0.5em}}\mathrm{nm}\text{\hspace{0.5em}(4\hspace{0.5em}}\mathrm{K}\mathrm{).}$ The seed layer and the second dot layer have essentially the same dot density of $\text{∼250\hspace{0.5em}μ}{\mathrm{m}}^{\text{−2}}$ due to the high degree of dot vertical alignment. The deposition amount for the second dot layer was selected to be 9 monolayers, which resulted in dots with convergent lateral size $\text{(∼62\hspace{0.5em}}\mathrm{nm})$ and stabilized facets, close to $\text{{011}.}$ The third layer, with the same amount of InGaAs as the second layer, had a dot density of $\text{∼350\hspace{0.5em}μ}{\mathrm{m}}^{\text{−2}},$ an average lateral dot size of $\text{∼71\hspace{0.5em}}\mathrm{nm},$ an average dot height of $\text{∼11\hspace{0.5em}}\mathrm{nm},$ and shallower side facets close to $\text{{023}.}$