Investigation of carrier dynamics in Zn1−xMgxO by time-resolved photoluminescence

Chernikov, A.; Horst, S.; Koch, Martin; Volz, Kerstin; Chatterjee, Sangam; Koch, S. W.; Wassner, Thomas A.; Laumer, Bernhard; Eickhoff, Martin

doi:10.1016/j.jlumin.2010.06.030

Cited by 16 publications

(12 citation statements)

References 25 publications

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“…The characteristic localization energy of each sample can be evaluated by the Stokes shift between SE and PL at room temperature or by the FWHM of PL at low temperature. The Stokes shift is found to be about twice the value of the FWHM at 5 K. For the sample with x ¼ 0.14 this value is 51 meV, in remarkable agreement with an earlier study, 39 where about 60 meV for x % 0:21 was evaluated as a characteristic localization energy.…”

Section: Comparison Of Emission and Absorption Energiessupporting

confidence: 91%

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Neumann

Cobet

Esser

et al. 2011

Journal of Applied Physics

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The characteristics of the excitonic absorption and emission around the fundamental bandgap of wurtzite Mg x Zn 1Àx O grown on c-plane sapphire substrates by plasma assisted molecular beam epitaxy with Mg contents between x ¼ 0 and x ¼ 0.23 are studied using spectroscopic ellipsometry and photoluminescence (PL) measurements. The ellipsometric data were analyzed using a multilayer model yielding the dielectric function (DF). The imaginary part of the DF for the alloys exhibits a pronounced feature which is attributed to exciton-phonon coupling (EPC) similar to the previously reported results for ZnO. Thus, in order to determine reliable transition energies, the spectral dependence is analyzed by a model which includes free excitonic lines, the exciton continuum, and the enhanced absorption due to EPC. A line shape analysis of the temperature-dependent PL spectra yielded in particular the emission-related free excitonic transition energies, which are compared to the results from the DF line-shape analysis. The PL linewidth is discussed within the framework of an alloy disorder model.

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Section: Comparison Of Emission and Absorption Energiessupporting

confidence: 91%

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Neumann

Cobet

Esser

et al. 2011

Journal of Applied Physics

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“…The rise of DX PL slightly lags behind the SX and reaches its maximum 45 ps after the SX. A kinetic analysis gives a rise time of ~30 ps which represents the population time of DX states after excitation, in good agreement with literature values for bulk ZnO [15].…”

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confidence: 88%

Nanoscale transport of surface excitons at the interface between ZnO and a molecular monolayer

et al. 2015

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Excitons play a key role for the optoelectronic properties of hybrid systems. We apply near-field scanning optical microscopy (NSOM) with a 100-nm spatial resolution to study the photoluminescence of surface excitons (SX) in a 20 nm thick ZnO film capped with a monolayer of stearic acid molecules. Emission from SX, donor-bound (DX), and -at sample temperatures T>20 K -free (FX) excitons is separated in steady-state and time-resolved photoluminescence spectra. The 4 meV broad smooth envelope of SX emission at T<10 K points to an inhomogeneous distribution of SX transition energies and spectral diffusion caused by diffusive SX transport on a 50 nm scale with a diffusion coefficient of D SX (T<10K)=0.30 cm²/s. PACS number(s): 68.37. Uv, 73.20.At, 78.66.Hf

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“…2,[28][29][30] For time resolved PL measurements, a standard streak-camera setup with a 100 fs Ti:sapphire laser as an excitation source was used. 31 …”

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confidence: 99%

Exciton confinement in homo- and heteroepitaxial ZnO/Zn1 − xMgxO quantum wells with x < 0.1

Laumer

Wassner

Schuster

et al. 2011

Journal of Applied Physics

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ZnO/Zn 1 À x Mg x O single quantum well (SQW) structures with well widths d W between 1.1 nm and 10.4 nm were grown by plasma-assisted molecular beam epitaxy both heteroepitaxially on c-plane sapphire and homoepitaxially on (000 1)-oriented bulk ZnO. A significantly reduced Mg incorporation in the top barrier related to the generation of stacking faults is observed for heteroepitaxial samples. Exciton localization is observed for both types of samples, while an enhancement of the exciton binding energy compared to bulk ZnO is only found for homoepitaxial SQWs for 2 nm d W 4 nm. Consistently, for homoepitaxial samples, the carrier dynamics are mainly governed by radiative recombination and carrier cooling processes at temperatures below 170 K, whereas thermally activated non-radiative recombination dominates in heteroepitaxial samples. The effects of polarization-induced electric fields are concealed for Mg concentrations x < 0.1 due to the reduction of the exciton binding energy, the screening by residual carriers as well as the asymmetric barrier structure in heteroepitaxial wells.

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Investigation of carrier dynamics in Zn1−xMgxO by time-resolved photoluminescence

Cited by 16 publications

References 25 publications

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Nanoscale transport of surface excitons at the interface between ZnO and a molecular monolayer

Exciton confinement in homo- and heteroepitaxial ZnO/Zn1 − xMgxO quantum wells with x < 0.1

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Investigation of carrier dynamics in Zn1−xMgxO by time-resolved photoluminescence

Cited by 16 publications

References 25 publications

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Nanoscale transport of surface excitons at the interface between ZnO and a molecular monolayer

Exciton confinement in homo- and heteroepitaxial ZnO/Zn1 − xMgxO quantum wells with x &lt; 0.1

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Exciton confinement in homo- and heteroepitaxial ZnO/Zn1 − xMgxO quantum wells with x < 0.1