Effect of Interatomic Distance of Constituent Nitrogen Atoms on its Localized Electronic State in Dilute GaAsN Thin Films Investigated by a Photoreflectance Spectroscopy

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