Structural and vibrational properties of molecular beam epitaxy grown cubic (Al, Ga)N/GaN heterostructures

The radio-frequency plasma-assisted molecular beam epitaxy of cubic AlyGa1- yN/GaN heterostructures on GaAs(001) substrates is reported. Rutherford bac kscattering spectroscopy, high resolution x-ray diffraction, and first-orde r micro-Raman spectroscopy measurements were used to characterize the struc tural and vibrational properties of the alloy epilayers. The Al content of the alloy is in the range from 0.07 <x <0.20. X-ray diffraction reciprocal space maps demonstrate the good crystal quality of the cubic (Al, Ga)N/GaN films. The measured Raman shift of the TO phonon mode of the AlyGa1-yN allo y is in good agreement with theoretical calculations. (C) 2001 American Ins titute of Physics.