Microstructure of the nitrogen-induced localized state in GaAsN thin films grown by chemical beam epitaxy

To investigate the microstructure of nitrogen-induced localized state (E_N) that perturbs the conduction band of GaAs host material, we adopted the photoreflectance measurements to chemical-beam-epitaxy grown GaAsN thin films. We measured both two split subbands to estimate correct values of E_N. It was clearly seen that estimated E_N decreased with increasing nitrogen content and temperature. By considering a change of a mean distance between neighboring nitrogen atoms, we concluded that the microscopic structure of E_N is not only an isolated nitrogen atom but also nitrogen-related complex, accompanied by low-order pairs of nitrogen atoms and/or nitrogen clusters.