AlxGa1−xN GROWTH BY Si/N TREATMENT OF SAPPHIRE SUBSTRATE: COMPARISON WITH OTHERS GROWTH TECHNIQUES

Abstract

AlxGa[Formula: see text]N films were grown on Si/N-treated sapphire substrate by atmospheric pressure metalorganic vapor phase epitaxy (AP-MOVPE) in a home-made vertical reactor. This process can be considered as randomly in situ epitaxial lateral overgrowth (ELO) technology. The growth firstly begins by three-dimensional (3D) mode and is completed in two-dimensional (2D) growth mode as shown by real time in situ laser [Formula: see text][Formula: see text]nm[Formula: see text] reflectometry measurements and confirmed by scanning electron microscopy (SEM) images. Secondary ion mass spectroscopy (SIMS) measurements evidence Al composition pulling effect in the AlxGa[Formula: see text]N layer. The Si/N treatment technique is compared to conventional AlxGa[Formula: see text]N growth techniques. The results of high-resolution X-ray diffraction (HRXRD), photoluminescence (PL) measurements and SEM images agree well on the fact that the Si/N treatment produces AlxGa[Formula: see text]N layers with comparable qualities of AlxGa[Formula: see text]N layers grown on high temperature GaN template but with much higher qualities than AlxGa[Formula: see text]N layers grown on low temperature AlN nucleation layer. Moreover, the Si/N treatment technique permits the growth of high quality AlxGa[Formula: see text]N layers with appreciable thicknesses with respect to the others techniques.