Field effect of photoluminescence from excitons bound to nitrogen atom pairs in GaAs

Field effect of photoluminescence due to excitons bound to nitrogen atom pairs in GaAs has been investigated for uniformly doped and atomic-layer-doped samples grown on (001) GaAs substrates. The intensities of excitonic photoluminescence lines due to distant nitrogen atom pairs decrease much more rapidly than those from closer pairs when the electric field is increased. In addition, photoluminescence due to the nearest neighbor pairs in atomic-layer-doped samples exhibits much more stable characteristics than that of uniformly doped samples against an applied electric field. This stability is observed only when the electric field is applied in either the [110] or [1̄10] direction. This anomalous field effect can be explained by considering the electron trapping process to the isoelectric N traps modulated by the electric field.