Dynamics of surface-excitonic emission in ZnO nanowires

Wischmeier, L.; Voss, T.; Rückmann, I.; Gutowski, J.; Mofor, A. Che; Bakin, A.; Waag, A.

doi:10.1103/physrevb.74.195333

Cited by 104 publications

(91 citation statements)

References 26 publications

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“…It has been showed, also, that surface effects can modify excitonic states at low temperatures [21], e.g. via the build-up of surface-excitons [22]. The existence of the latter was also demonstrated in GaN NWs [23], simultaneously with dramatic ageing effects (radical changes in micro-PL spectra, after long exposure to ambient air) resulting from surface alteration.…”

Section: Introductionmentioning

confidence: 97%

Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

Lefèbvre

Albert²,

Ristić³

et al. 2012

Superlattices and Microstructures

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GaN and InGaN nanocolumns of various compositions are studied by room-temperature photoluminescence (PL) under different ambient conditions. GaN nanocolumns exhibit a reversible quenching upon exposure to air under constant UV excitation, following a t 1/2 time dependence and resulting in a total reduction of intensity by 85-90%, as compared to PL measured in vacuum, with no spectral change. This effect is not observed when exposing the samples to pure nitrogen. We attribute this effect to photoabsorption and photodesorption of oxygen that modifies the surface potential bending. InGaN nanocolumns, under the same experimental conditions do not show the same quenching features: The high-energy part of the broad PL line is not modified by exposure to air, whereas a lower-energy part, which does quench by 80-90%, can now be distinguished. We discuss the different behaviors in terms of carrier localization and possible composition or strain gradients in the InGaN nanocolumns.

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Section: Introductionmentioning

confidence: 97%

Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

Lefèbvre

Albert²,

Ristić³

et al. 2012

Superlattices and Microstructures

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“…[1][2][3] In general, the nanowires can be characterized as ZnO single crystals with a large aspect ratio, i.e., their length in c-axis direction is significantly exceeding all other lateral dimensions, with the latter ones being in the 10 to some hundred nanometer range. This implies that nanowires have a significantly increased surfaceto-volume ratio when compared to standard bulk crystals, resulting in considerably strong surface effects 4 in nanowirebased optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Localized versus delocalized states: Photoluminescence from electrochemically synthesized ZnO nanowires

Voss

Bekeny

Gutowski

et al. 2009

Journal of Applied Physics

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We analyze the near-band-edge photoluminescence of electrochemically deposited ZnO nanowires and directly correlate the photoluminescence properties with the carrier concentration in the nanowires as determined from electrochemical impedance spectroscopy. We find a donor density of 8 ϫ 10 19 cm −3 in the as-deposited nanowires and show that the near-band-edge emission results from band-to-band recombination processes ͑delocalized states͒. A photoluminescence band centered at 3.328 eV scales with the diameter of the nanowires and is assigned to recombination processes involving surface states. We show that annealing at 500°C in air reduces the donor density in the nanowires by more than one order of magnitude, leading to sharp excitonic transitions in the electrochemically deposited nanowires.

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“…Reparaz et al 10 reported that the intensity of this line increases with a decrease in the size of nanorods and also assigned it to a D o X. Alternatively, Richters et al 37 and Wischmeier et al 38 observed the same line at 5 K in catalyst-assisted physical vapor deposited nanorods and assigned it to surface bound excitons (SX). Dumcenco et al 2 also assigned a line at 3.367 eV (at 9 K) in micro-rods grown by catalyst-assisted thermal evaporation, to surface bound excitons.…”

Section: Figurementioning

confidence: 90%

Low temperature near band edge recombination dynamics in ZnO nanorods

Urgessa

Botha

Eriksson

et al. 2014

Journal of Applied Physics

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Articles you may be interested inThe surface-plasmon-resonance and band bending effects on the photoluminescence enhancement of Agdecorated ZnO nanorods J. Appl. Phys. 116, 063108 (2014) The recombination dynamics of neutral donor bound excitons (D o X: I 4 , I 6/6a ) and near band edge defect-related emission in solution grown ZnO nanorods are investigated using steady state and time-resolved photoluminescence (PL) measurements. The effects of annealing are also studied. Low temperature steady state PL shows a systematic removal of the I 4 line after annealing at 450 C and the subsequent domination of I 6a in these PL spectra. Additionally, the time decay of the I 4 , I 6/6a, free exciton (FX), and basal plane stacking fault-related (BSF) PL transitions are studied as a function of annealing temperature. For the various annealing temperatures studied, the PL decay is described by a bi-exponential profile with a fast component (contribution from the surface) and slow component (related to bulk recombination). The fast component dominates in the case of as-grown and low temperature annealed samples (anneal temperatures up to 300 C), suggesting the presence of surface adsorbed impurities. For samples annealed above 400 C, the effects of the surface are reduced. The sample annealed at 850 C produced an overall enhancement of the crystal quality. The underlying mechanisms for the observed PL characteristics are discussed based on near surface band bending caused by surface impurities. V C 2014 AIP Publishing LLC.

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Dynamics of surface-excitonic emission in ZnO nanowires

Cited by 104 publications

References 26 publications

Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

Localized versus delocalized states: Photoluminescence from electrochemically synthesized ZnO nanowires

Low temperature near band edge recombination dynamics in ZnO nanorods

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