Photoluminescence dynamics in strontium titanate

Rubano, Andrea; Ciccullo, Francesca; Paparo, D.; Granozio, F. Miletto; Uccio, U. Scotti di; Marrucci, Lorenzo

doi:10.1016/j.jlumin.2009.02.037

Cited by 14 publications

(27 citation statements)

References 19 publications

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“…There are many studies reporting on the photo-carrier recombination dynamics of amorphous, undoped and doped STO thin films [31,18,28,43,44]. However, the PL emission data for un- In our work we did not observe low energy PL emission bands however we observed low dielectric constants compare to high temperature grown STO films.…”

Section: Accepted Manuscriptcontrasting

confidence: 60%

Effect of O2/Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO3 thin films deposited by RF sputtering at room temperature

et al. 2015

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Effect of O 2 /Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO 3 thin films deposited by RF sputtering at room temperature, Thin Solid Films (2015), SrTiO 3 (STO) thin films have been prepared by reactive rf magnetron sputtering on Si (100) and UV fused silica substrates at room temperature. The effect of oxygen flow on film characteristics was investigated at a total gas flow of 30 sccm, for various O 2 /O 2 +Ar flow rate ratios. As-deposited films were annealed at 700 °C in oxygen atmosphere for 1 h. Postdeposition annealing improved both film crystallinity and spectral transmittance. Film microstructure, along with optical and electrical properties were evaluated for both asdeposited and annealed films. Abroad photoluminescence emission was observed with in the spectral range of 2.75-3.50 eV for all STO thin films irrespective of their deposition parameters. Upon annealing, the optical band gap of the film deposited with 0% O 2 concentration slightly blue-shifted, while the other samples grown at higher oxygen partial pressure did not show any shift. Refractive indices (n) (at 550 nm) were in the range of 2.05 to 2.09, and 2.10 to 2.12 for as-deposited and annealed films, respectively. Dielectric constant values (at 100 kHz) within the range of 30-66 were obtained for film thicknesses less than 300 nm, which decreased to~30-38 after post-deposition annealing.

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Section: Accepted Manuscriptcontrasting

confidence: 60%

Effect of O2/Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO3 thin films deposited by RF sputtering at room temperature

et al. 2015

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“…The most used technique is photoluminescence (PL), which has been crucial in the study of self-trapped carriers and excitons. As to light excitation, continuous UV lasers [10], as well as pulsed laser of ns [22,23] and ps [24,25,28,30] duration having energies slightly above the STO band gap, have been used and have provided a substantial amount of information. The power excitation densities in the ps experiments are quite high (0.01-10 mJ/cm 2 ), which has relevant consequences on the results.…”

Section: Luminescence Experimentsmentioning

confidence: 99%

“…More relevant for our review are the studies based on the monitoring of oxygen vacancy defects and Ti 3+ states at the surfaces and its impact on the luminescence behavior [20,21]. However, it is important to mention that the luminescence spectra and behavior observed under different excitation sources from UV light [10,17,[22][23][24][25][26][27][28][29][30] to X-rays [16], electrons [31], and ion beams [5,32], having very different penetration depths, show a similar pattern apparently associated to a bulk response. In spite of these considerations, we believe that surface luminescence is beyond the scope of our review and deserves independent attention.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances on Carrier and Exciton Self-Trapping in Strontium Titanate: Understanding the Luminescence Emissions

et al. 2019

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An up-to-date review on recent results for self-trapping of free electrons and holes, as well as excitons, in strontium titanate (STO), which gives rise to small polarons and self-trapped excitons (STEs) is presented. Special attention is paid to the role of carrier and exciton self-trapping on the luminescence emissions under a variety of excitation sources with special emphasis on experiments with laser pulses and energetic ion-beams. In spite of the extensive research effort, a definitive identification of such localized states, as well as a suitable understanding of their operative light emission mechanisms, has remained lacking or controversial. However, promising advances have been recently achieved and are the objective of the present review. In particular, significant theoretical advances in the understanding of electron and hole self-trapping are discussed. Also, relevant experimental advances in the kinetics of light emission associated with electron-hole recombination have been obtained through time-resolved experiments using picosecond (ps) laser pulses. The luminescence emission mechanisms and the light decay processes from the self-trapped excitons are also reviewed. Recent results suggest that the blue emission at 2.8 eV, often associated with oxygen vacancies, is related to a transition from unbound conduction levels to the ground singlet state of the STE. The stabilization of small electron polarons by oxygen vacancies and its connection with luminescence emission are discussed in detail. Through ion-beam irradiation experiments, it has recently been established that the electrons associated with the vacancy constitute electron polaron states (Ti3+) trapped in the close vicinity of the empty oxygen sites. These experimental results have allowed for the optical identification of the oxygen vacancy center through a red luminescence emission centered at 2.0 eV. Ab-initio calculations have provided strong support for those experimental findings. Finally, the use of Cr-doped STO has offered a way to monitor the interplay between the chromium centers and oxygen vacancies as trapping sites for the electron and hole partners resulting from the electronic excitation.

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“…Among various ATiO 3 materials, SrTiO 3 system is one of the most investigated material due to their peculiar quantum paraelectric nature, semiconducting behaviour, in addition with it has been widely used in the field of pyroelectric detectors, electro optical modulators, thin film capacitors and optical memories [4]. SrTiO 3 also been used as a substrate material for superconducting cuprates and CMR materials [5]. SrTiO 3 has wide band gap (3.2 eV) and further, the optical band gap can be tuned by doping suitable transition metal (TM) ions.…”

Section: Introductionmentioning

confidence: 99%

Carrier mediated ferromagnetism in Cr doped SrTiO3 compounds

Muralidharan

Anbarasu

Perumal

et al. 2015

J Mater Sci: Mater Electron

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The carrier doped ferromagnetism in SrTiO 3 compounds has been investigated for the importance in the field of multiferroics and spintronics. Polycrystalline pure and Cr doped SrTiO 3 compounds were synthesized by glycol assisted sol-gel method. Powder X-ray diffraction (XRD) studies reveal the simple cubic perovskite structure of all the prepared compounds. The grain size and lattice strain of the compounds were estimated from the powder XRD pattern which evidences the incorporation of Cr in SrTiO 3 system. The local order and disorder parameter of the compounds was investigated by laser Raman spectroscopy. The change in particles to rod like surface morphology while increasing Cr doping concentration was examined by scanning electron microscope and transmission electron microscopy. The enhancement of oxygen vacancy while increasing Cr doping concentration in SrTiO 3 system and reduction in Ti 4? to Ti 3? states was identified by X-ray photoelectron spectroscopy. The UVVis absorption spectra evidence the distinctive shift of absorption edge exclusively for Cr doped SrTiO 3 compounds. Photoluminescence (PL) spectra of the compounds reveal defective states and decrease in PL intensity due to the influence of Cr in SrTiO 3 . Electron paramagnetic resonance analysis of Cr doped compounds reveals the paramagnetic nature of the dopants. The magnetization studies of all the prepared compounds emphasis carrier mediated diamagnetic to ferromagnetic phase transition in due with the presence of carriers induced by Cr. It is also evident that the highest dopant concentration of Cr in SrTiO 3 system exhibits reversal ferromagnetism. The enhancement of magnetization and ferromagnetic ordering has been understood in terms of carrier-mediated Ruderman-KittelKasuya-Yosida interaction theory. The present work also demonstrates the influence of surface morphology on the occurrence of ferromagnetism in Cr doped SrTiO 3 compounds.

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Photoluminescence dynamics in strontium titanate

Cited by 14 publications

References 19 publications

Effect of O2/Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO3 thin films deposited by RF sputtering at room temperature

Effect of O2/Ar flow ratio and post-deposition annealing on the structural, optical and electrical characteristics of SrTiO3 thin films deposited by RF sputtering at room temperature

Recent Advances on Carrier and Exciton Self-Trapping in Strontium Titanate: Understanding the Luminescence Emissions

Carrier mediated ferromagnetism in Cr doped SrTiO3 compounds

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