Growth of GaN layer by metal-organic chemical vapor deposition system with a novel three-flow reactor

For the first time, this paper reports a novel kind of three-flow reactor which can be developed for metal-organic chemical vapor deposition (MOCVD) system to grow GaN-based structures. Two parallel carrier gas-flow for Group-III sources and NH₃ separated by a quartz plate which are also parallel to the substrate are used. The N₂, which is used as a sub-flow, flows through a quartz filter perpendicular to the substrate where it meets the two parallel group III and group V source flows. This new flow arrangement enhances the mixture of group III-V sources at the contacting substrate, compared with the previous three parallel laminar gas MOCVD systems due to the perpendicular direction of the N₂ sub-flow. Based on this MOCVD system with this special configuration, a mirror-like epitaxial GaN layer on sapphire substrate is obtained with an excellent uniformity. Also, the quality of the GaN layers are characterized by room temperature photoluminescence (PL) and X-ray diffraction (XRD) measurements, where the full-width at half-maximum (FWHM) of 41.12 meV for PL spectra and FWHM of about 220 arcsec for XRD rocking curve were measured, respectively. In addition, the carrier concentration and Hall mobility are found to be 2.6×10¹⁷/cm³ and 300 cm²/V s, respectively.