Abstract
The effects of pair number and pair thickness in the multiple-pair buffer layer on the quality of GaN epitaxial layers grown by a separate-flow reactor of metallorganic chemical vapor deposition (MOCVD) are presented. The optimized condition to obtain the best quality of GaN epitaxial layers is to grow to four-pair buffer layer with a pair thickness of 4 μm. Under this optimum condition, the FWHM of DC-XRD is decreased 150 arcsec, and the mobility and carrier concentration are greatly enhanced to 450 cm 2 /V s and 3×10 17 cm -3 , respectively. The GaN quality are much improved by growing more pair numbers and a thicker pair in the buffer layer.