Strong coupling between bi-dimensional electron gas and nitrogen localized states in heavily doped GaAs1−xNx structures

We report a low-temperature photoluminescence spectra (LTPL) of GaAs1−xNx layers and two-dimension electron gas (2DEG) GaAs1−xNx/AlGaAs modulation doped heterostructure grown on GaAs substrates by molecular beam epitaxy (MBE) with low nitrogen content [N] = 2 × 1018 cm−3. At low temperature, PL spectra of GaAs1−xNx layers are governed by several features associate to the excitons bound to nitrogen complexes, these features disappear in (2DEG) GaAs1−xNx/AlGaAs modulation doped heterostructure and the PL peak energy decrease with the laser power excitation. This effect is explained by the strongly coupling of the (2DEG) fundamental state with the nitrogen localized states. An activated energy of about 55 meV is deduced by photoluminescence measurements in the 10-300 K range for a laser power excitation P = 6 W/cm2.