Band gap energy of GaNAs grown on GaAs(001) substrates by metalorganic molecular-beam epitaxy

Band gap energy of GaNAs alloys grown on GaAs(0 0 1) substrates by metalorganic molecular-beam epitaxy was studied. The GaNAs alloys were characterized by high-resolution X-ray diffraction and Fourier transform absorption spectroscopy measurements. The absorption spectra were shifted to the lower energy by increasing the N composition. When the N composition in GaNAs alloys is less than 1%, the measured band gap energy is very close to the theoretical band gap energy based on the dielectric model. However, for the N composition larger than 1%, the band gap energy is considerably deviated from the dielectric model and approaches the theoretical band gap energy based on the first-principles supercell models. (C) 1998 Elsevier Science B.V. All rights reserved.