High-quality GaN/Si(111) epitaxial layers grown with various Al_(0.3)Ga_(0.7)N/GaN superlattices as intermediate layer by MOCVD

摘要

We have grown and characterized GaN/Si(111) epitaxial layers having different total thicknesses and periods of Al_(0.3)Ga_(0.7)N/GaN superlattices using metalorganic chemical vapor depositon. When the total thickness of Al_(0.3)Ga_(0.7)N/ GaN superlattice is 60 nm, GaN/Si(111) epitaxy shows the best surface and crystal quality. Under the same total thickness of Al_(0.3)Ga_(0.7)N/GaN superlattice of 60 nm, as the number of periods of Al_(0.3)Ga_(0.7)N/GaN superlattices increases, the quality of GaN/Si(111) epitaxy is also improved. GaN/Si(111) epitaxy grown with optimized Al_(0.3)Ga_(0.7)N/GaN superlattice of total thickness of 60 nm and 20 periods, shows crack distance of about 120 nm between cracks, FWHM of double crystal X-ray diffractometry rocking curve for GaN(0002) of 690 arcsec and FWHM of photoluminescence at RT of 34.49 MeV, which is compared with the best results reported for GaN/Si(111), so far. Therefore, we obtained a high-quality and nearly crack-free GaN/Si(111) epitaxy by optimizing Al_(0.3)Ga_(0.7)N/ GaN superlattice, possibly for the applications of LED or other photon devices, and, we found that the optimized total thickness and periods of Al_(0.3)Ga_(0.7)N/GaN superlattice play a very important role in the improvement of quality and reducing cracks in the growth of GaN/Si(111) epitaxy.