Interrelation between Light Emitting and Structural Properties of Si Nanoclusters Embedded in SiO 2 and Al 2 O 3 Hosts
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Interrelation between Light Emitting and Structural Properties of Si Nanoclusters Embedded in SiO2 and Al2O3 Hosts L. Khomenkova1, O. Kolomys1, V. Strelchuk1, A. Kuchuk1, V. Kladko1, M. Baran1, J. Jedrzejewski3, I.Balberg3, P. Marie2, F. Gourbilleau2, N. Korsunska1 1
V. Lashkaryov Institute of Semiconductor Physics, 45 Pr. Nauky, Kyiv 03028, Ukraine CIMAP/ENSICAEN, 6 Blvd. Maréchal Juin, 14050 Caen cedex 4, France 3 Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel 2
ABSTRACT The present work deals with the comparative investigation of Si-ncs embedded in SiO2 and Al2O3 dielectrics grown by RF magnetron sputtering on fused quarts substrate. The effect of post-deposition processing on the evolution of microstructure of the films and their optic and luminescent properties was investigated. It was observed that photoluminescence (PL) spectra of Six(SiO2)1-x films showed one PL band, which peak position shifts from 860 nm to 700 nm when the x decreases from 0.7 to 0.3. It is due to exciton recombination in Si-ncs. For Six(Al2O3)1-x films, several PL bands peaked at about 570-600 nm and 700-750 nm and near-infrared tail or band peaked at about 800 nm were found. Two first PL bands were ascribed to different oxygendeficient defects of oxide host, whereas near-infrared PL component is due to exciton recombination in Si-ncs. The comparison of both types of the samples showed that the main radiative recombination channel in Six(SiO2)1-x films is exciton recombination in Si-ncs, while in Six(Al2O3)1-x films the recombination via defects prevails due to higher amount of interface defects in the Six(Al2O3)1-x caused by stresses. INTRODUCTION The realization of low-cost integrated optoelectronic devices fully based on well-developed Si-based CMOS technology (i.e. all-in-one Si chip) is important task. In this regard, silicon nanocrystallites (Si-ncs) attract considerable interest due to significant transformation of their optical and electrical properties caused by quantum-confinement effect [1,2]. Being embedded in dielectric hosts, Si-ncs offer potential applications in optoelectronic devices that were demonstrated during last decades for Si-ncs-SiO2 systems [3-6]. However, the downscaling of microelectronic devices requires the elaboration of novel materials to overcome bottleneck of silicon oxide as a gate material. In this regard, other dielectrics such as ZrO2, HfO2 and Al2O3 are considered as promising gate dielectrics [7]. It was also demonstrated that Si-ncs embedded in such high-k host offer a wider application for nonvolatile memories due to the higher performance of the corresponding devices [8,9]. Among different dielectrics, Al2O3 is not well addressed as photonic material. At that, it has relatively higher refractive index (1.73 at 1.95 eV) in comparison with that of SiO2 (1.46 at 1.95 eV) at similar band gap energies offering better light confinement, making compact device structures possible. It was shown an application of alumina-based waveguides fabricated by solgel techniques for optical
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