Atomic ordering and structural determination of AlGaN/AlN/Si(111) thin films using anomalous X-ray scattering.

The atomic structure and atomic ordering of AlGaN/AlN/Si(111) thin films were studied using regular X-ray diffraction (XRD) and anomalous X-ray scattering (AXS). From regular XRD, both the Al composition and strain status of the AlGaN films are determined. AXS spectra were obtained near Ga K absorption edge at both the fundamental (0002) Bragg peak and non-vanishing forbidden (0001) peak. From this (0001) Bragg peak, long range atomic ordering with 2 bilayer periodicity is confirmed and the order parameter, S is determined from the integrated intensity ratio that is maximized upto 0.08 near x approximate to 0.5. The AXS near forbidden peak can be an effective method to reveal the atomic ordering of thin films.