Synthesis of wide band gap nanocrystals by ion implantation E. Borsella a, * ,C.deJuli an Fern andez a , M.A. Garc  ıa a , G. Mattei a , C. Maurizio a , P. Mazzoldi a , S. Padovani a , C. Sada a , G. Battaglin b , E. Cattaruzza b , F. Gonella b , A. Quaranta c , F. D’Acapito d , M.A. Tagliente e , L. Tapfer e a INFM, Department of Physics, University of Padova, Via F. Marzolo 8, I-35131 Padova, Italy b INFM, Department of Physical Chemistry, University of Venice, Dorsoduro 2137, I-30123 Venezia, Italy c INFM, Department of Materials Engineering, University of Trento, Via Mesiano 77, Trento, Italy d INFM, GILDA CRG-ESRF, 6 Rue Jules Horowitz, B.P. 220, F-38043 Grenoble, France e Pa.s.t.i.s.-CNRSM, Strada Statale 7 Appia, I-72100 Brindisi, Italy Abstract Nanocrystals of wide band gap materials (GaN and In 2 O 3 ) were synthesized by sequential ion implantation in di- electric substrates, followed by thermal annealing of the samples. Transmission electron microscopy, extended X-ray absorption fine structure spectroscopy and grazing incidence X-ray diffraction analyses confirmed the formation of GaN and In 2 O 3 crystalline nanoparticles. Blue shift of the near-edge photoluminescence (PL) band (quantum con- finementeffect)wasobservedforGaNnanocrystals.AstrongPLbandpeakedat3.35eVwasdetecteduponexcitation of In 2 O 3 nanocrystals at 5.20 eV. Ó 2002 Elsevier Science B.V. All rights reserved. Keywords: Gallium nitride; Indium oxide; Ion implantation; Nanocomposites 1. Introduction Thereisagreatdealofinterestonthesynthesis and characterization of wide band gap materials, since they have many possible applications in op- tical and/or electronic devices [1]. However, little information is available on the controlled prepa- ration of nanoaggregates of these materials that should exhibit novel, attracting properties. Here wereportresultsobtainedonthesynthesisbyion- implantation of nanoaggregates of two popular wide band gap materials, namely GaN and In 2 O 3 . They have remarkably close energy band gaps (E g ofGaNis3.45eVand E g ofIn 2 O 3 isabout3.6eV). Cluster growth after sequential ion implantation into dielectric substrates was promoted by an- nealing treatments in either reducing or oxidizing atmosphere. 2. Experimental Different dielectric substrates were sequentially implanted with Ga and N, or In and N ions as Nuclear Instruments and Methods in Physics Research B 191 (2002) 447–451 www.elsevier.com/locate/nimb * Corresponding author. Tel.: +39-049-827-7044; fax: +39- 049-827-7003. E-mail address: borsella@padova.infm.it (E. Borsella). 0168-583X/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S0168-583X(02)00590-6