Dynamics of Excitons in Bare and Organic/Metal coated InP Nanowires

ORAL

Abstract

We investigate the exciton dynamics in bare and organic/metal coated wurzite/zincblende (WZ/ZB) InP nanowires (NW) by temperature-dependent time-integrated (TI) and time-resolved (TR) photoluminescence (PL). Aluminum quinoline (Alq$_{\mathrm{3}})$ as well as Alq$_{\mathrm{3}}$/Mg:Ag covered NW heterostructures are fabricated by organic molecular beam deposition. PL measurements on bare InP nanowires at 15 K reveal two emission bands at 1.45, and 1.48 eV originating from indirect WZ/ZB and point-defect (PD) trapped excitons, respectively. TR PL traces show an approximately single exponential decay for PD trapped excitons with a lifetime of 2 ns and biexponential decay for indirect WZ/ZB excitons with lifetimes of 3.3 ns and 14 ns. In Alq$_{\mathrm{3}}$ covered NWs we observe a stronger emission from both exciton transitions and longer decay times for indirect excitons indicating surface state passivation at the Alq$_{\mathrm{3}}$/NW interface. In Alq$_{\mathrm{3}}$/Mg:Ag NWs the PD trapped exciton emission is notably reduced which is attributed to a fast energy-transfer from free excitons in the WZ segments to plasmon oscillations in the metal film. The emission from indirect excitons is still comparable to the PL yield of bare NWs.

*The support of URC at UC and of the Australian Research Council is kindly acknowledged.

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Authors

  • Masoud Kaveh

    • University of Cincinnati
    • Department of Physics, University of Cincinnati

  • Qiang Gao

    • Australian National University, Canberra, Australia
    • Department of Electronic Materials Engineering, Australian National University, Canberra, Australia
    • Australian National University
    • Department of Electronic and Materials Engineering, Australian National University, Canberra, ACT, 0200, Australia

  • Chennupati Jagadish

    • Australian National University, Canberra, Australia
    • Department of Electronic Materials Engineering, Australian National University, Canberra, Australia

  • Gerd Duscher

    • University of Tennessee, Knoxville
    • Department of Materials Science and Engineering, University of Tennessee, Knoxville

  • Hans-Peter Wagner

    • Department of Physics, University of Cincinnati
    • University of Cincinnati