title: Optical Properties of Strained Wurtzite Gallium Phosphide Nanowires.
abstract: Wurtzite gallium phosphide (WZ GaP) has been predicted to exhibit a direct bandgap in the green spectral range. Optical transitions, however, are only weakly allowed by the symmetry of the bands. While efficient luminescence has been experimentally shown, the nature of the transitions is not yet clear. Here we apply tensile strain up to 6% and investigate the evolution of the photoluminescence (PL) spectrum of WZ GaP nanowires (NWs). The pressure and polarization dependence of the emission together with a theoretical analysis of strain effects is employed to establish the nature and symmetry of the transitions. We identify the emission lines to be related to localized states with significant admixture of Γ7c symmetry and not exclusively related to the Γ8c conduction band minimum (CBM). The results emphasize the importance of strongly bound state-related emission in the pseudodirect semiconductor WZ GaP and contribute significantly to the understanding of the optoelectronic properties of this novel material.
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB, Eindhoven, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Greil
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB, Eindhoven, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Assali
authors.affiliation: Department of Mechanical Engineering, Kobe University , Kobe 657-8501, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Isono
authors.affiliation: Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität , Max-Wien-Platz 1, 07743 Jena, Germany.|King Abdullah University of Science & Technology , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Belabbes
authors.affiliation: Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität , Max-Wien-Platz 1, 07743 Jena, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Bechstedt
authors.affiliation: TNO Technical Sciences , De Rondom 1, 5612 AP, Eindhoven, The Netherlands.
authors.forename: F O
authors.initials: FO
authors.lastname: Valega Mackenzie
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB, Eindhoven, The Netherlands.
authors.forename: A Yu
authors.initials: AY
authors.lastname: Silov
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB, Eindhoven, The Netherlands.|Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA, Delft, The Netherlands.
authors.forename: E P A M
authors.initials: EP
authors.lastname: Bakkers
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , 5600 MB, Eindhoven, The Netherlands.
authors.forename: J E M
authors.initials: JE
authors.lastname: Haverkort
keywords: Wurtzite semiconductor; band structure; localized state; photoluminescence; strain; symmetry