High quality self-nucleated Al<i>x</i>Ga1−<i>x</i> N layers on (00.1) sapphire by low-pressure metalorganic chemical vapor deposition

Abstract

High quality AlxGa1−xN alloy films with x&amp;lt;0.4 have been prepared on self-nucleated (00.1) sapphire substrates by low-pressure metalorganic chemical vapor deposition. It has been shown that the lattice constant of the films varies linearly with alloy composition x (Vegard’s law is obeyed) and that homogeneous and inhomogeneous strain and alloy clustering are minimized in these self-nucleated AlxGa1−xN films. Consistent with their reduced strain and chemical uniformity, the derived optical band gaps of these AlxGa1−xN films also show a linear dependence on alloy composition x, yielding a bowing parameter b≊0 eV.