STRAIN EFFECTS IN EPITAXIAL GAN GROWN ON ALN-BUFFERED SI(111)

Growth of GaN thin films on AlN-buffered Si(111) by ultrahigh-vacuum rf glow discharge reactive magnetron sputtering is reported. Epitaxy of GaN is established by x-ray and electron diffraction. Raman scattering from the epitaxial films consistent with that of wurtzitic GaN is observed. The ion energies involved in the growth process are quantified by measuring the plasma potentials of the Ar/N2 glow discharge by an emissive Langmuir probe technique. As a function of increasing input power, a systematic increase in ion energies and a systematic straining of the GaN lattice are observed. Measured GaN phonon energy scales with lattice strain. © 1994 American Institute of Physics.