title: Semipolar (202̅1̅) GaN and InGaN Light-Emitting Diodes Grown on Sapphire.
abstract: We have demonstrated growing uniform and purely nitrogen polar semipolar (202̅1̅) GaN epilayers on 2 in. patterned sapphire substrates. The as-grown surface of (202̅1̅) GaN is composed of two stable facets: (101̅0) and (101̅1̅). A chemical mechanical polishing process was further used to planarize the surface with a final surface root-mean-square roughness of less than 1.5 nm over an area of 10 × 10 μm2. InGaN light-emitting diodes were grown on a polished (202̅1̅) GaN/sapphire template with an electroluminescence emission at around 490 nm. Our work exhibits the potential to produce high-quality nitrogen-polar semipolar GaN templates and optoelectronic devices on large-area sapphire substrates with economical feasibility.
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06520, United States.|Saphlux Inc. , Branford, Connecticut 06405, United States.
authors.forename: Jie
authors.identifier: http://orcid.org/0000-0001-6245-2879
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06520, United States.
authors.forename: Joowon
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06520, United States.
authors.forename: Kanglin
authors.initials: K
authors.lastname: Xiong
authors.affiliation: Department of Mechanical Engineering & Materials Science, Yale University , New Haven, Connecticut 06520, United States.|Energy Sciences Institute, Yale University , Yale West Campus, West Haven, Connecticut 06516, United States.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Mechanical Engineering & Materials Science, Yale University , New Haven, Connecticut 06520, United States.|Energy Sciences Institute, Yale University , Yale West Campus, West Haven, Connecticut 06516, United States.
authors.forename: Judy J
authors.identifier: http://orcid.org/0000-0002-6346-2814
authors.initials: JJ
authors.lastname: Cha
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06520, United States.
authors.forename: Jung
authors.initials: J
authors.lastname: Han
keywords: MOCVD; N-polar; light-emitting diodes; patterned sapphire substrate; selective area growth; semipolar GaN