Optical band gap dependence on composition and thickness of InxGa1-xN (0 <x < 0.25) grown on GaN

Band gap measurements have been carried out in strained and relaxed InxGa1- xN epilayers with x < 0.25. Values of x were determined from x-ray diffract ion of relaxed films. The lowest energy absorption threshold, measured by t ransmittance, was found to occur at the same energy as the peak of the phot oluminescence spectrum. Bowing parameters for both strained and relaxed fil ms were determined to be 3.42 and 4.11 eV, respectively. The dependence of the band gap shift, Delta E-g, on strain is presented. (C) 1999 American In stitute of Physics. [S0003-6951(99)04844-5].