Epitaxial two-dimensional nitrogen atomic sheet in GaAs

Abstract

We have grown an epitaxial two-dimensional nitrogen (N) atomic sheet in GaAs by using the site-controlled N δ-doping technique. We observed a change of the electronic states in N δ-doped GaAs from the isolated impurity centers to the delocalized impurity band at 1.49 eV with increasing N-doping density. According to the excitation-power- and temperature-dependent photoluminescence (PL) spectra, the emission related to localized levels below the impurity band edge was dominant at low excitation power and temperature, whereas the effects of the localized levels can be neglected by increasing the excitation power and temperature. Furthermore, a clear Landau shift of the PL-peak energy was observed at several Tesla in the Faraday configuration, in contrast to the case in the impurity limit.