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

The molecular beam epitaxy of cubic GaN on Si(001) substrates, which were c overed by a 4 nm thick beta-SiC layer, is reported. The structural and opti cal properties of the cubic GaN epilayers were studied by transmission elec tron microscopy, high-resolution x-ray diffraction, and low-temperature pho toluminescence measurements. We find clear evidence for the growth of cubic GaN layers almost free of hexagonal inclusions. The density of extended de fects and the near band edge photoluminescence of the cubic GaN layers grow n at substrate temperatures of 835 degrees C is comparable to that of high quality cubic GaN epilayers grown by molecular beam epitaxy on GaAs (001) s ubstrates. (C) 2000 American Institute of Physics. [S0003-6951(00)03413-6].