Emission dynamics of hybrid plasmonic gold/organic GaN nanorods

Abstract

We studied the emission of bare and aluminum quinoline (Alq)/gold coated wurtzite GaN nanorods by temperature- and intensity-dependent time-integrated and time-resolved photoluminescence (PL). The GaN nanorods of ∼1.5 μm length and ∼250 nm diameter were grown by plasma-assisted molecular beam epitaxy. Gold/Alq coated GaN nanorods were synthesized by organic molecular beam deposition. The near band-edge and donor-acceptor pair luminescence was investigated in bare GaN nanorods and compared with multilevel model calculations providing the dynamical parameters for electron-hole pairs, excitons, impurity bound excitons, donors and acceptors. Subsequently, the influence of a 10 nm gold coating without and with an Alq spacer layer was studied and the experimental results were analyzed with the multilevel model. Without a spacer layer, a significant PL quenching and lifetime reduction of the near band-edge emission is found. The behavior is attributed to surface band-bending and Förster energy transfer from excitons to surface plasmons in the gold layer. Inserting a 5 nm Alq spacer layer reduces the PL quenching and lifetime reduction which is consistent with a reduced band-bending and Förster energy transfer. Increasing the spacer layer to 30 nm results in lifetimes which are similar to uncoated structures, showing a significantly decreased influence of the gold coating on the excitonic dynamics.

Effect of Au substrate and coating on the lasing characteristics of GaAs nanowires

“…The NWs were subsequently coated conformally with a 5 nm thick Al 2 O 3 film using atomic layer deposition (ALD) in order to reduce atmospheric oxidation and metal induced band-bending. 40 , 41 More details about the growth and the optical characterization of these NWs can be found in Ref. 14 and in the SI Sect.…”

“…In addition, high Zn doping increases the differential gain and reduces the transparency carrier density due to the high hole concentration already present 14 . A thin Al 2 O 3 spacer layer of ~ 5 nm in thickness was deposited around the NWs to suppress atmospheric oxidation and to reduce metal induced band bending 40 , 41 , at the Au/GaAs interface. As a new approach, we deposited a nominally 10 nm thick Au film around the NWs resulting in a coaxial hybrid Au/Al 2 O 3 /GaAs shell-core NW laser structure.…”

Lasing from InP Nanowire Photonic Crystals on InP Substrate

“…The InP NW array was subsequently conformally coated with a 10 nm‐thick Al 2 O 3 film using atomic layer deposition to suppress atmospheric oxidation of the InP NW surface, which causes nonradiative recombination, and to reduce band‐bending due to adsorbed atmospheric ions. [ 30–32 ]…”

Index matching in multilayered organic waveguides

“…Organic films can be easily deposited on a variety of substrates without lattice matching including low-cost and flexible substrates facilitating bendable [14][15][16][17][18] and wearable [19] electronic devices. Multilayered organic films also allow including metal layers or nanostructures [20,21] for plasmonic applications leading to enhanced OLED or solar cell performances [15,22]. Furthermore, organic multilayer structures provide unique opportunities to tailor organic waveguides with desired optical anisotropy and nonlinearity [23,24].…”