Early manifestation of localization effects in diluted Ga(AsN)

The electron effective mass, $m_e,$ and extent of exciton wave function, $r_{\mathrm{exc}},$ were derived in ${\mathrm{GaAs}}_{\text{1−y}}{\mathrm{N}}_y$ $\text{(y=0.043\%–0.5\%)}$ from magnetophotoluminescence measurements. With an increase in nitrogen concentration, we find that $m_e$ and $r_{\mathrm{exc}}$ undergo a rapid increase and squeezing, respectively, even for $\text{y≈0.1\%.}$ This quite early manifestation of nitrogen-induced localization effects imposes important constraints on existing theoretical models.