Compositional pulling effect in high Al-content AlGaN films grown on (0001) sapphire substrates

In this presentation, we report strain induced compositional pulling phenomenon in high Al content AlGaN films grown on AlN-coated sapphire substrates. It was found that Al constituent in a high Al content AlGaN film was expelled out of the film in the initial stage of the growth followed by the growth of a AlGaN film having higher Al content. The AlGaN films were characterized by X-ray diffractometry (XRD) for composition evaluation. Absorption spectroscopy was employed for the measurements of absorption spectra of the AlGaN films.