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 met alorganic molecular-beam epitaxy was studied. The GaNAs alloys were ch aracterized by high-resolution X-ray diffraction and Fourier transform absorption spectroscopy measurements. The absorption spectra were shi fted to the lower energy by increasing the N composition. When the N c omposition in GaNAs alloys is less than 1%, the measured band gap ener gy is very close to the theoretical band gap energy based on the diele ctric model. However, for the N composition larger than 1%, the band g ap energy is considerably deviated from the dielectric model and appro aches the theoretical band gap energy based on the first-principles su percell models. (C) 1998 Elsevier Science B.V. All rights reserved.