Ion beam crystallization of InAs/GaAs(001) nanostructures

A technique for ion beam crystallization of InAs/GaAs(001) nanostructures with quantum dots is proposed. The GaAs and InAs sputtering yields in the energy range $E_{\mathrm{Ar}+}$ = 200–300 eV and argon beam incidence angle $\theta$ = 30$^\circ$ are refined. It is demonstrated that growth rates of up to 0.1 ML/s for InAs and 0.05 ML/s for GaAs can be attained. According to atomic force and electron microscopy, photoluminescence, and Raman scattering data, enhancement of beam current density from 5 to 15 $\mu$A/cm$^2$ at energy $E_{\mathrm{Ar}+}$ = 200 eV and substrate temperature $T$ = 480$^\circ$C leads to an increase in the quantum dot lateral size from 15 to 25 nm and in surface anisotropy from 2 $\cdot$ 10$^{10}$ to 9 $\cdot$ 10$^{10}$ cm$^{-2}$. Current density growth to 20 $\mu$A/cm$^2$ at the same ion energy is accompanied by a sharp increase in the mean lateral size of quantum dots to 70 nm and a decrease in the density to 3 $\cdot$ 10$^{10}$ cm$^{-2}$.