Optical and structural behaviour of Mn implanted sapphire C. Marques a,b , N. Franco a,b , A. Kozanecki c , R.C. da Silva a,b , E. Alves a,b, * a LFI, Dep. Fı ´sica, Instituto Tecnolo ´ gico e Nuclear, Estrada Nacional 10, 2686-953 Sacave ´m, Portugal b Centro de Fı ´sica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa, Portugal c Institute of Physics Polish Academy of Sciences, 32/46 Lotniko ´ w Al., 02-668 Warszawa, Poland Available online 11 July 2006 Abstract Sapphire single crystals were implanted at room temperature with 180 keV manganese ions to fluences up to 1.8 · 10 17 cm 2 . The samples were annealed at 1000 °C in oxidizing or reducing atmosphere. Surface damage was observed after implantation of low fluences, the amorphous phase being observed after implantation of 5 · 10 16 cm 2 , as seen by Rutherford backscattering spectroscopy under channelling conditions. Thermal treatments in air annealed most of the implantation related defects and promoted the redistribution of the manganese ions, in a mixed oxide phase. X-ray diffraction studies revealed the presence of MnAl 2 O 4 . On the contrary, similar heat treatments in vacuum led to enhanced out diffusion of Mn while the matrix remained highly damaged. The analysis of laser induced luminescence performed after implantation showed the presence of an intense red emission. Ó 2006 Elsevier B.V. All rights reserved. PACS: 61.46.+w; 61.72.Ww; 81.07.Bc; 82.80.Yc Keywords: Ion implantation; Transition metals; Photoluminescence; RBS-C; Sapphire 1. Introduction The physical changes induced by the presence of immisci- ble species in solids have been extensively studied, for exam- ple through chemical doping or following ion implantation. In the latter case, the implanted systems are left in metasta- ble states and subsequent annealing is required to remove the implantation damage [1]. Oxides are important techno- logical materials, being one of the most widely used hosts. Among these, sapphire has unique optical transparency from the ultraviolet to near infrared region, making it an excellent substrate for optical studies, being also resistant to chemical and thermal extreme conditions. On sapphire, mechanical, electric or optical changes or improvements are usually sought as well as the study of the production and behaviour of irradiation damage [2]. The most recent studies are related to the response of embedded metallic nanostructures, since electrons confined in the metal nano- particulates show surface plasmon resonance and provide ultrafast nonlinear behaviour [3]. This can find application in optoelectronics on switching or wave guiding devices [4]. In this work we study the effect of Mn implantation and subsequent annealing on single crystal a-Al 2 O 3 . The implantation was carried out with 180 keV Mn + at room temperature (RT) and the resulting structural changes stud- ied using Rutherford backscattering spectroscopy under channelling conditions (RBS-C) and X-ray diffraction (XRD) while optical properties were measured through optical absorption (OA) and photoluminescence (PL) at RT. These analyses were performed after implantation and after annealing in oxidizing or reducing atmosphere at 1000 °C for 1 h. 2. Experimental details Sapphire single crystals, 400 lm thick, with h0001i (c-samples) orientation and optically polished surfaces, 0168-583X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2006.04.090 * Corresponding author. Address: LFI, Dep. Fı ´sica, Instituto Tecnolo ´g- ico e Nuclear, Estrada Nacional 10, 2686-953 Sacave ´m, Portugal. Tel.: +351 21 9946086; fax: +351 21 9941525. E-mail address: ealves@itn.pt (E. Alves). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 250 (2006) 90–94 NIM B Beam Interactions with Materials & Atoms