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 ( E N ) 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 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 adjacent 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.