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.

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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