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0942-W08-36

On the Structural and Optical Properties of ZnO Nanoparticles Formed in Silica by Ion Implantation Maria Antonella Tagliente1, Marcello Massaro1, Giovanni Mattei2, Paolo Mazzoldi2, Giovanni Pellegrini2, Valentina Bello2, and Daniela Carbone1 1 UTS MAT, ENEA, Centro Ricerche Brindisi, SS. Appia km 714, Brindisi, Italy, 72100, Italy 2 Dipartimento di Fisica, INFM, Università di Padova, via Marzolo 8, Padova, Italy, 50124, Italy

ABSTRACT Zinc-oxide nanoparticles embedded in silica glass were fabricated by ion implantation of Zn ions of 130 keV and up to a dose of 2×1017 ions/cm2, followed by thermal annealing in O2 atmosphere at 800°C and for 1h. Glancing-incidence x-ray diffraction and transmission electron microscopy results show zinc crystalline nanoclusters with an average diameter of 13nm and placed around a Rp=70nm, in the as-implanted sample. The thermal oxidation promotes the diffusion of the Zn atoms preferentially towards the surface of the silica where ZnO particles of 65nm in diameter where found and a small diffusion toward the bulk where ZnO clusters of 5nm in diameter were observed. A relatively strong exciton emission peak from the ZnO particles was observed in the photo-luminescence spectrum at 380nm. +

INTRODUCTION Zinc Oxide (ZnO) is a II-VI semiconductor material with a wide direct band gap of 3.37 eV at room temperature (RT) [1]. In the past decades, the material has been used for a variety of applications such as gas sensors, surface acoustic wave devices, or transparent contacts. Recently, ZnO has gained a new substantial interest primarily because to its potentialities for optoelectronic and spintronic applications [2]. The renewed interest has been fueled by the availability of high-quality bulk substrates [3], reports of p-type conduction [4] and theoretical predictions of its ferromagnetic behavior at room temperature when doped with transitions metals [5]. In the domain of optoelectronics, its main applications include devices emitting in the blue and UV regions by exploiting its wide band-gap such as light-emitting and laser diodes. With respect to several wide band-gap semiconductor materials, ZnO has the advantage of a larger exciton binding energy (about 60 meV) [6] which paves the way for an intense near-bandedge excitonic emission at room and higher temperatures. On the other hand, a band gap engineering can be also achieved by the incorporation of Cadmium and Magnesium atoms into the ZnO lattice [2]. Many techniques have been used to prepare ZnO in various forms, such as single crystals, powders and films. In the past few years, the great attention toward materials with nanometric size have motivated a number of studies on the synthesis of ZnO nanocrystals [7]. Ion implantation is one of the most effective and versatile techniques to obtain nanoparticles [8]. ZnO particles embedded in silica matrix have been successfully prepared by ion implantation followed by thermal oxidation [9-10]. However, before this system can be exploited for optoelectronic devices, a careful s