Composition dependence of the band-gap energy of GaAsN alloys

The composition dependence of the band-gap energy of GaAs1-xNx layers on GaAs substrates is studied by using photocurrent measurements and high-resolution X-ray diffraction. The GaAs1-xNx alloys were grown using metalorganic chemical vapor deposition. The photocurrent spectra show clear near-band-edge peaks at 77 and 297 K, and the peak energies drastically decrease with increasing nitrogen composition due to band-gap bowing in the GaAs1-xNx alloy. This result indicates that the bowing parameter reaches 25.39 eV for very low nitrogen incorporation (x = 0.31 %), and decreases with increasing nitrogen composition. An empirical double exponential composition dependence of the bowing parameter is presented.