Comparison of the ion induced charge collection in Si epilayer and SOI devices Toshio Hirao a, * , Hidenobu Mori b , Jamie Stuart Laird a , Shinobu Onoda b , Hisayoshi Itoh a a Department of Materials Development, Radiation Engineering Division, Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan b Graduate Engineering, Applied Science, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292, Japan Abstract It is known that the single-event phenomena (SEP) are the malfunction of micro electronics devices caused by the impact of an energetic heavy ion. Improving the tolerance of devices to the SEP requires a better understanding of basic charge collection mechanisms on the timescales of the order of picoseconds. In order to better elucidate these mech- anisms, we measure the fast transient current resulting from heavy ion strikes with a fast sampling data collection system and a heavy ion microbeam line at JAERI. In this paper we report on differences in both the transient current and charge collection from 15 MeV carbon ions on silicon-on-insulator, Si epilayer and bulk p þ n junction diodes and charge transportation under MeV ion injection is discussed. Ó 2003 Elsevier B.V. All rights reserved. Keywords: Single-event phenomena; Heavy-ion microbeam; Collected charge; Funneling effect 1. Introduction Single-event upset (SEU) is triggered when electric charges induced by energetic ion incidence upon an integrated memory circuit are collected at its electrode and the amount of collected charges exceeds a value known as a critical charge of the circuit within a very short time period. There- fore, for the improvement of SEU tolerance, un- derstanding of the charge collection mechanism is necessary which includes charge generation, re- combination and transport along ion tracks in semiconductor [1,2]. Measurements of SEU current transients and accurate evaluation of the amount of collected charges are strongly required. Because SEU cur- rent transients vary in a picosecond time scale depending on the location of ion impingement on a device, such sophisticated experimental tech- niques are required as accurate positioning of in- cident ion at a desired area of the circuit and precise waveform measurement of the high speed transient currents. Several attempts have been made for the direct measurements of extremely fast strikes on the diodes. Charge collection mechanisms such as * Corresponding author. Tel.: +81-27-346-9324; fax: +81-27- 346-9687. E-mail address: hirao@taka.jaeri.go.jp (T. Hirao). 0168-583X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0168-583X(03)01011-5 Nuclear Instruments and Methods in Physics Research B 210 (2003) 221–226 www.elsevier.com/locate/nimb