The University of British Columbia

X-ray absorption and fluorescence spectra have been measured at the nitrogen K edge of dilute GaNxAs1-x alloys. The x-ray spectra are in good agreement with an sp(3)s(*) tight-binding model in which nitrogen is included in a supercell configuration and the disorder in the nitrogen distribution is neglected. A strong peak in the x-ray absorption spectrum is interpreted as a nitrogen resonant state in the conduction band rather than as an electron-hole exciton. The tight-binding calculation is also in good agreement with the observed nitrogen concentration dependence of the optical band gap.