Abstract
We have investigated the hydride vapor-phase epitaxy growth of -oriented GaN thick films on patterned sapphire substrates (PSSs) . From characterization by atomic force microscopy, scanning electron microscopy, double-crystal X-ray diffraction, and photoluminescence (PL), it is determined that the crystalline and optical qualities of GaN epilayers grown on the cylindrical PSS are better than those on the flat sapphire. However, two main crystalline orientations and dominate the GaN epilayers grown on the pyramidal PSS, demonstrating poor quality. After etching in the mixed acids, these GaN films are dotted with oblique pyramids, concurrently lining along the direction, indicative of a typical N-polarity characteristic. Defect-related optical transitions of the GaN epilayers are identified and detailedly discussed in virtue of the temperature-dependent PL. In particular, an anomalous blueshift–redshift transition appears with an increase in temperature for the broad blue luminescence due to the thermal activation of the shallow level.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
