AlGaN films grown by chloride-hydride chemical vapour deposition (CH CVD)

Epitaxial Al_xGa_1-xN films over all compositional range (0≤x≤1) have been grown by CH CVD in Al-Ga-HCl-NH₃ reaction system. Alloy composition was reproducibly controlled by the variation of chloride concentration ratio (A1C1₃ to GaCl) in gas phase. The precision measurements of lattice parameters were performed. Both parameters a and c tend to be higher than the values predicted by Vegard’s law. The epitaxial orientation relationships for films grown on sapphire with different orientations are determined. From analysis of absorption spectra the alloy compositional dependence of band gap was determined as following: E_g(eV)=3.491 + 2.779x - 0.35x(1 - x).