Time-resolved photoluminescence lifetime measurements of the Γ5 and Γ6 free excitons in ZnO

Reynolds, D. C.; Look, David C.; Jogai, B.; Hoelscher, J. E.; Sherriff, R. E.; Harris, M. T.; Callahan, Michael J.

doi:10.1063/1.1305546

Cited by 147 publications

(58 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The lifetime over 12 ns is much longer than the bulk free-exciton lifetime of 322 ps at 2 K. 23 The same kind of slow luminescence has been observed in CdSe and CdS NCs and they are attributed to dark excitons. 6,7,10 In the systems with dark exciton in the ground state, the radiative recombination occurs only when the excitons are thermally excited from the dark state to the bright state.…”

Section: Resultsmentioning

confidence: 56%

Observation of dark exciton luminescence from ZnO nanocrystals in the quantum confinement regime

Yamamoto

Mishina

2011

Phys. Rev. B

View full text Add to dashboard Cite

Time-resolved luminescence measurements are performed on high-quality ZnO nanocrystals in a quantum confinement regime prepared by fast cooling and succeeding surface passivation. A very long luminescence lifetime of ∼0.1 μs, which is indicative of the existence of a dark exciton state, is observed. The temperature dependence of the lifetime and the luminescence peak energy is successfully accounted for by a thermal equilibrium model of excitonic dark and bright states.

show abstract

Section: Resultsmentioning

confidence: 56%

Observation of dark exciton luminescence from ZnO nanocrystals in the quantum confinement regime

Yamamoto

Mishina

2011

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…As far as the green luminescence is concerned, despite a vast number of investigations, its nature is yet to be understood. The following luminescence centers were assumed to be responsible for the green luminescence: impurity Cu2+ ions [11,12], zinc vacancies VZn [13,14], oxygen vacancies VO [14][15][16][17], interstitial zinc ions Zni [18], oxygen antisites ZnO [19], and transitions Zni → VZn [20]. As a result, the authors of review [20] came to the conclusion that various centers may be involved in the green luminescence simultaneously.…”

Section: Luminescence Characteristics Of Zinc Oxidementioning

confidence: 99%

Optical and luminescence properties of zinc oxide (Review)

Родный¹,

Khodyuk²

2011

Opt. Spectrosc.

375

190

View full text Add to dashboard Cite

Abstract-We generalize and systematize basic experimental data on optical and luminescence properties of ZnO single crystals, thin films, powders, ceramics, and nanocrystals. We consider and study mechanisms by which two main emission bands occur, a short-wavelength band near the fundamental absorption edge and a broad long-wavelength band, the maximum of which usually lies in the green spectral range. We determine a relationship between the two luminescence bands and study in detail the possibility of controlling the characteristics of ZnO by varying the maximum position of the short-wavelength band. We show that the optical and luminescence characteristics of ZnO largely depend on the choice of the corresponding impurity and the parameters of the synthesis and subsequent treatment of the sample. Prospects for using zinc oxide as a scintillator material are discussed. Additionally, we consider experimental results that are of principal interest for practice.

show abstract

“…Lifetime values vary depending on the carrier concentration in the semiconductor, the temperature, the surface, the interface, etc., but as a general rule, the better the crystal quality is, the longer the lifetime becomes. The carrier lifetime in ZnO is typically in the range between a few hundred picoseconds to a few nanoseconds [34,35,36]. Chichibu et al [37] report about the improvement of ZnO epilayer films by the elimination of point defects by variation of different growth parameters including substrate choice, growth temperature, annealing time and pressure.…”

Section: Carrier Lifetime In Znomentioning

confidence: 99%

Deep level related photoluminescence in ZnMgO

Trunk

Venkatachalapathy

Galeckas

et al. 2010

Applied Physics Letters

View full text Add to dashboard Cite

Zinc oxide (ZnO) has been used in a wide range of products for many years, including, among others, varistors, surface acoustic wave devices and cosmetics. Besides these established applications, ZnO and its ternary alloys are now also being considered as potential materials for optoelectronic applications, such as light emitting diodes, photovoltaics, sensors, displays, etc. Unlike other materials, which could be used alternatively, ZnO has the advantage of being inexpensive, chemically stable and relatively plentiful. In spite of the long research history, fabrication of defect free ternary alloys and stable p-type ZnO is still challenging. The aim of this work was therefore to provide a better understanding of ZnO ternary alloys, so that -based on the gained knowledge -their optical properties can be further improved and, in a second step, optoelectronic applications based on these materials can soon be commercialized. The work carried out in this thesis was two-fold: the first part aimed at identifying the origin of defect related luminescence phenomena in ZnMgO, and the second part was dedicated to the exploration of a novel ZnCdO-based heterostructure photovoltaic applications.In the case of ZnMgO, luminescence properties of deep level defects were studied by photoluminescence (PL) spectroscopy and a model was proposed to explain the changes in the deep band emission with increasing Mg content. In this model, the observed trends can be understood by considering interaction of native zinc and oxygen defects of the ZnO sublattice with Mg interstitials (Mg i ). In summary, the deep level bands at 3.0 and 2.8 eV, which show a blueshift with increasing Mg content, were assigned to free-to-bound type transitions between zinc interstitials (Zn i ) with the valence band edge and between the conduction band edge with zinc vacancies (V Zn ), respectively. A red band at 2.0 eV, which does not show an apparent shift of the peak energy for increasing Mg content, is associated with the oxygen vacancies (V O ). Two luminescence bands at 2.3 and 2.5 eV, which are redshifted for higher Mg concentrations, were assigned to transitions between zinc and oxygen interstitials and between zinc interstitials and zinc vacancies, respectively. The redshift is interpreted in terms of a competing supply of electrons from slightly deeper Mg i donor states. The ZnMgO band gap diagram, which the model is based on, has contributed to gain valuable information about the nature of the deep defects both in ZnO and ZnMgO and is therefore of fundamental interest.In the second part of this work, focused on ZnCdO, a stacked heterostructure was designed for iii iv Abstract application in a photoelectrochemical cell, which is used for hydrogen production by photoelectrolysis using the semiconductor as an absorber. Optical and photoelectrochemical measurements led to the conclusion that the optical emission band for the ZnCdO heterostructures is broadened compared to a ZnO single layer. The broadened emission could be explained by combined ...

show abstract

Time-resolved photoluminescence lifetime measurements of the Γ5 and Γ6 free excitons in ZnO

Cited by 147 publications

References 7 publications

Observation of dark exciton luminescence from ZnO nanocrystals in the quantum confinement regime

Observation of dark exciton luminescence from ZnO nanocrystals in the quantum confinement regime

Optical and luminescence properties of zinc oxide (Review)

Deep level related photoluminescence in ZnMgO

Contact Info

Product

Resources

About