title: Controlled synthesis of AlN/GaN multiple quantum well nanowire structures and their optical properties.
abstract: We report the controlled synthesis of AlN/GaN multi-quantum well (MQW) radial nanowire heterostructures by metal-organic chemical vapor deposition. The structure consists of a single-crystal GaN nanowire core and an epitaxially grown (AlN/GaN)(m) (m = 3, 13) MQW shell. Optical excitation of individual MQW nanowires yielded strong, blue-shifted photoluminescence in the range 340-360 nm, with respect to the GaN near band-edge emission at 368.8 nm. Cathodoluminescence analysis on the cross-sectional MQW nanowire samples showed that the blue-shifted ultraviolet luminescence originated from the GaN quantum wells, while the defect-associated yellow luminescence was emitted from the GaN core. Computational simulation provided a quantitative analysis of the mini-band energies in the AlN/GaN superlattices and suggested the observed blue-shifted emission corresponds to the interband transitions between the second subbands of GaN, as a result of quantum confinement and strain effect in these AlN/GaN MQW nanowire structures.
authors.affiliation: Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
authors.forename: Fang
authors.initials: F
authors.lastname: Qian
authors.forename: Megan
authors.initials: M
authors.lastname: Brewster
authors.forename: Sung K
authors.initials: SK
authors.lastname: Lim
authors.forename: Yichuan
authors.initials: Y
authors.lastname: Ling
authors.forename: Christopher
authors.initials: C
authors.lastname: Greene
authors.forename: Oleg
authors.initials: O
authors.lastname: Laboutin
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Johnson
authors.forename: Silvija
authors.initials: S
authors.lastname: Gradečak
authors.forename: Yu
authors.initials: Y
authors.lastname: Cao
authors.forename: Yat
authors.initials: Y
authors.lastname: Li
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004579:Electron Transport; D005708:Gallium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D012031:Refractometry; D013499:Surface Properties
chemical_list: D017607:Aluminum Compounds; D046911:Macromolecular Substances; C473348:gallium nitride; C052045:aluminum nitride; D005708:Gallium