High quality GaN epilayers grown on carbon nanotube patterned sapphire substrate by metal–organic vapor phase epitaxy

Abstract

Aligned carbon nanotube films were utilized to pattern a c-plane sapphire substrate. High quality GaN was obtained by epitaxy growth on carbon nanotube patterned sapphire substrates (CPSS) by a metal–organic vapor phase epitaxy system. Results of X-ray diffraction and transmission electron microscopy (TEM) confirmed the improvement of crystalline quality of GaN by introduction of the carbon nanotube film. A large number of voids with sizes of tens to hundreds of nanometers were observed on carbon nanotubes by scanning electron microscopy (SEM) and TEM. The dislocation annihilation around voids was believed to be helpful for the reduction of dislocation density. Performance of light-emitting diodes manufactured on CPSS was also clearly improved, as 15% enhancement of luminous intensity at 20 mA, and 50% delay of saturation current from 80 mA to 120 mA.