Cubic GaN epilayers grown by molecular beam epitaxy on thin β-SiC/Si (001) substrates

The molecular beam epitaxy of cubic GaN on Si(001) substrates, which were covered by a 4 nm thick β-SiC layer, is reported. The structural and optical properties of the cubic GaN epilayers were studied by transmission electron microscopy, high-resolution x-ray diffraction, and low-temperature photoluminescence measurements. We find clear evidence for the growth of cubic GaN layers almost free of hexagonal inclusions. The density of extended defects and the near band edge photoluminescence of the cubic GaN layers grown at substrate temperatures of 835 °C is comparable to that of high quality cubic GaN epilayers grown by molecular beam epitaxy on GaAs (001) substrates.