Micro-photoluminescence study on defects induced by ion microbeam in silica glass Masato Murai a , Hiroyuki Nishikawa a, * , Tomoharu Nakamura b , Hirohiko Aiba b , Yoshimichi Ohki b , Masakazu Oikawa c , Takahiro Sato c , Tomihiro Kamiya c a Department of Electrical Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan b Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan c TIARA, JAEA Takasaki, 1233 Watanuki-machi, Takasaki, Gunma 370-1292, Japan Abstract We have evaluated the irradiation effects by ion microbeam on silica glass for various ion species by means of a micro-photolumines- cence technique. Defect generation and refractive index change were observed for silica at the area of 10 lm · 50 lm scanned by ion microbeam of H + , He + ,N 4+ ,C 4+ ,O 4+ , and Si 5+ with energy from 1.7 to 18 MeV. The l-PL spectroscopy measurements were performed along the side surface perpendicular to the microbeam irradiated surface. Based on the comparison with a result of SRIM (stopping and range of ions in matter) simulation, the defect generation mechanism was discussed in terms of the energy deposition processes due to electronic and nuclear stopping powers. We conclude that the electronic stopping power is responsible for the defect generation at the track of ions. The effect of the nuclear stopping power is also not negligibly small at the end of range. Ó 2007 Elsevier B.V. All rights reserved. PACS: 79.20.Rf; 78.55.Hx; 78.55.Àm Keywords: Optical properties; Luminescence 1. Introduction Since a refractive index change is one of the irradiation effects by ion beam irradiation [1,2], local irradiation effects induced by scanning ion microbeam have been studied as a way to fabricate optical waveguides and gratings on silica glass [3–6]. In our previous studies, irradiation effects induced by ion microbeam have been studied using micro-Raman and photoluminescence (PL) spectroscopy and an atomic force microscopy [4,5]. In this paper, we studied distribution of irradiation effects such as defect generation induced by ion microbeam using a micro-photoluminescence (l-PL) measurement. Attention has been paid to the role of electronic and nuclear stopping powers in the defect generation and refractive index changes. 2. Experimental procedures Silica glasses (Nippon Silica Glass, ES, [OH]: 1300 ppm) were used as substrates for ion microbeam irradiation that was carried out at JAEA Takasaki Research Institute, Japan. Several ion species (1.7 MeV H + , 1.7 MeV He + , 13.6 MeV N 4+ , 15 MeV C 4+ , 15 MeV O 4+ , and 18 MeV Si 5+ ) were used for irradiation using beamlines installed at the 3 MV single-ended or tandem accelerators. The microbeam was focused to about 1 lm and scanned over a stripe area with dimensions of 10 lm · 50 lm. Irradiation was made over the right-angled edges of the sample so that the cross-sectional images can be easily observed from the side surface by a phase microscope (20 times objective lens) or l-PL spectroscopy (Nanofinder, 0022-3093/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2006.10.053 * Corresponding author. Tel.: +81 3 5859 8217; fax: +81 3 5859 8201. E-mail address: nishi@sic.shibaura-it.ac.jp (H. Nishikawa). www.elsevier.com/locate/jnoncrysol Journal of Non-Crystalline Solids 353 (2007) 537–541