Growth of GaN on on-axis 6H-SiC (0001) Si substrates with an AlN buffer layer was performed by molecular-beam epitaxy. The effects of SiC surface reconstruction on the lattice relaxation of AlN buffer layers and the crystalline quality of GaN layers were studied. High-temperature HCl-gas etching followed by HF chemical treatment resulted in an atomically flat SiC surface with a 1ϫ1 structure. The AlN layer grown on the surface showed slow lattice relaxation. GaN grown on the AlN buffer layer exhibited the narrowest ͑0002͒ x-ray rocking curve of 70 arcsec and 10 7 cm Ϫ2 screw-type dislocation density, which was two orders of magnitude smaller than that of GaN grown on as-received substrates.
The effects of growth temperature and V/III flux ratio on the GaAsSb crystalline quality were studied. Phase separation was suppressed within a narrow window of growth temperature. 1-μm-thick GaAsSb layers which exhibited single peaks in X-ray diffraction (XRD) measurement were successfully obtained grown at the optimum temperature. XRD and photoluminescence (PL) measurements revealed that V/III flux ratio also has an optimum value. It was found that the type-II InGaAs/GaAsSb superlattice with GaAsSb grown at the optimized growth condition seems to have an excellent optical property, because the PL peak energy exhibited peculiar dependence on temperature suggesting transition between the conduction band of InGaAs and the valance band of GaAsSb.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.