Magnetic and electric field effects of photoluminescence of excitons bound to nitrogen atom pairs in GaAs

The Magnetic and electric field effects of photoluminescence of excitons bound to nitrogen atom pairs in GaAs have been investigated for nitrogen delta-doped samples grown on (001) GaAs substrates. The excitons bound to nitrogen atom pairs produce a number of photoluminescence lines. However, these lines are much fewer than those observed in uniformly nitrogen-doped samples because of the limited spacing between two-dimensionally distributed nitrogen atoms. Among these lines, those appearing at 1.488, 1.476, and 1.428 eV are the most dominant. In this study, the characteristics of these dominant lines are investigated by an applying external field. The observed phenomena are explained by assuming that there is a continuous flow of excitons from a lower to a higher binding energy state under continuous excitation. Each photoluminescence line is found to split into two or more lines without applying an external field. The lines show a further split under a magnetic field and are finally quenched when the magnetic field is increased. The photoluminescence intensity of each line is modulated by the localization of excitons by a magnetic field and by the delocalization by an electric field.