Low temperature photo-induced carrier dynamics in the GaAs$_{\mathrm{0.985}}$N$_{\mathrm{0.015}}$ alloy*

We report the exploration of photo-induced carrier dynamics in the GaAs$_{\mathrm{0.985}}$N$_{\mathrm{0.015}}$ Alloy. The time-resolved and high magnetic field-dependent photoluminescence experiments were carried out to identify the radiative transitions, and the localized and delocalized states at various excitation power and temperature. A nonmonotonic dependence of the PL energy on temperature at low laser power, and the observation of two different decay times at the temperature below 100 K indicate the free electrons undergo a delocalization to localization transition with decreasing temperature. In the low temperature region, the localization is further enhanced by an applied high magnetic field, and an unexpected high field blocking of the diamagnetic shift was observed.