Photoluminescence of RE‐doped thin metal oxide films

Abstract

PACS 78.55.Hx Photoluminescence (PL) of pure and Sm 3+ -doped TiO 2 , ZrO 2 and HfO 2 thin films was studied at temperatures of 6-300 K under interband excitation by using pulsed lasers and synchrotron radiation in the energy range of 4-20 eV. PL excitation spectra and decay kinetics were recorded. The thin films were prepared by using both the atomic layer deposition (ALD) and the sol-gel process. The ion implantation was applied to dope the ALD-grown films with Sm 3+ ions, whereas an in-situ doping was used in the sol-gel process.The main emission of undoped materials was attributed to the radiative decay of self-trapped excitons (STE). In doped materials, a broadband emission superposed by Sm 3+ emission lines was observed. The broadband emission was attributed to the decay of STE as well as various bound excitonic states. The differencies in the PL excitation spectra of studied films were assigned to the damage produced by ion implantation and uncontrolled impurities incorporated into the films in sol-gel process. [3][4][5] where dielectric materials with a relatively wide band gap and high refractive index (see [6] and the references therein) are needed. Due to low phonon frequencies [7,8] the matrices are expected to be suitable hosts for rare earth activators. Because of their high density and high Z-values, rare-earth-activated ZrO 2 and HfO 2 can be also attractive as scintillating materials [9].The ALD method enables the growth of epitaxial and high-density nanocrystalline films [10-13], whereas the films produced by using the sol-gel process are usually amorphous and of quite high porosity [14][15][16]. The advantage of the latter process is that it enables convenient in situ doping. The in situ doping of thin films in the ALD process is quite a complex task. For doping of ALD-grown films one can employ, however, the ion implantation method [17], which allows introducing optical centres in well-defined amounts and controlled spatial distribution into the substance.Various rare-earth (RE) ions have previously been incorporated into sol-gel-derived as well as ALDgrown metal oxide films and the optical properties of the materials has been studied [6,14,[18][19][20][21]. In this contribution we are investigating the PL characteristics of both ALD-grown and sol-gel-derived Sm

Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts

“…Photoluminescence can be quenched by defects and, in particular, quenching was observed in the case of defects created on purpose by co-doping [53]. Additionally, emission from the rare earth impurity increases with the annealing temperature and well resolved PL spectra are observed for Sm 3+ fitted into regular environment [54].…”

Spectroscopic and crystal-field analysis of energy levels of Eu3+ in SnO2 in comparison with ZrO2 and TiO2

“…Wide-gap (E g > 3 eV) semiconductors like SnO 2 (stannia), TiO 2 (titania) or ZrO 2 (zirconia) are technologically interesting since, due to an efficient energy transfer from host to rare-earth (RE) activators, these materials could be employed in the form of very thin phosphor layers and impose the potential of carrier-mediated excitation of RE ions yet providing transparency throughout the visible range and reduced thermal quenching of RE emission [1][2][3]. Moreover, such doped oxides are relatively easily prepared in various morphologies employing "soft" wet chemistry techniques.…”

Optical Investigation of Sm doped ZrO2

“…3a). This defect related emission is totally quenched at RT [ 12 ]. The PL decay curves of the three sites of Sm 3+ have different behaviours (Fig.…”