Growth and Structural Properties of InAlGaN Quaternary Alloys on Sapphire Substrates by RF-MBE

InAlGaN quaternary alloys were grown on nitrided sapphire, AlN nuclear layer and GaN layer by radio-frequency plasma-excited molecular beam epitaxy (RF-MBE). Reflection high-energy electron diffraction (RHEED), Rutherford back-scatter spectrometry (RBS), atomic-force microscopy (AFM) and high resolution X-ray diffraction (HRXRD) were used to characterize the InAlGaN alloys. Different buffer layers strongly affect the growth mode, indium content and depth distribution, surface morphology and crystal quality of InAlGaN quaternary alloys. The experimental results show that the InAlGaN film grown on GaN layer can acquire layer-by-layer growth mode, uniform indium deep distribution, flat surface with RMS of InAlGaN to be 2.2nm and smallest full-width at half-maximum (FWHM) of InAlGaN (0002) peak to be 4.8 arcmin