title: Vertically aligned InGaN nanowires with engineered axial In composition for highly efficient visible light emission.
abstract: We report on the fabrication of novel InGaN nanowires (NWs) with improved crystalline quality and high radiative efficiency for applications as nanoscale visible light emitters. Pristine InGaN NWs grown under a uniform In/Ga molar flow ratio (UIF) exhibited multi-peak white-like emission and a high density of dislocation-like defects. A phase separation and broad emission with non-uniform luminescent clusters were also observed for a single UIF NW investigated by spatially resolved cathodoluminescence. Hence, we proposed a simple approach based on engineering the axial In content by increasing the In/Ga molar flow ratio at the end of NW growth. This new approach yielded samples with a high luminescence intensity, a narrow emission spectrum, and enhanced crystalline quality. Using time-resolved photoluminescence spectroscopy, the UIF NWs exhibited a long radiative recombination time (τr) and low internal quantum efficiency (IQE) due to strong exciton localization and carrier trapping in defect states. In contrast, NWs with engineered In content demonstrated three times higher IQE and a much shorter τr due to mitigated In fluctuation and improved crystal quality.
authors.affiliation: Department of Physics, Chonnam National University, Gwangju 500-757, Republic of Korea.|Department of Physics, Faculty of Science, Beni-Suef University, Beni-Suef 62511, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ebaid
authors.affiliation: Department of Physics, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors.forename: Yang-Seok
authors.initials: YS
authors.lastname: Yoo
authors.affiliation: Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors.forename: Seung-Hyuk
authors.initials: SH
authors.lastname: Lim
authors.affiliation: Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors.forename: Yong-Hoon
authors.initials: YH
authors.lastname: Cho
authors.affiliation: Department of Physics, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Sang-Wan
authors.initials: SW
authors.lastname: Ryu