Journal of Luminescence 102–103 (2003) 156–161 Preferential suppression of Auger energy backflow by separation of Er ions from carriers with a thin oxide interlayer in Er-doped porous silicon T. Kimura a, *, H. Isshiki a , T. Ishida a,b , T. Shimizu a,c , S. Ide a,b , R. Saito a , S. Yugo a a Department of Electronic Engineering, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu-shi, Tokyo 182-8585, Japan b Hitachi Ltd., Kandasurugadai 4-6, Chiyoda, Tokyo, Japan c Sony Corporation, Kitashinagawa 6-7-35, Shinagawa, Tokyo, Japan Abstract Strong enhancement of the Er-related 1:54 mm emission was obtained at room temperature from Er-doped porous silicon (PSi), when host PSi was slightly preoxidized at 9001C before Er incorporation. It was speculated that the formation of the oxide interlayer played an important role. Separate measurements of the energy transfer and the Auger deexcitation between carriers in Si crystallites and Er ions were carried out using a two-beam (cw and pulse) excitation method for various preoxidation time which was supposed to change the oxide interlayer thicknesses from about 1 to 10 nm: It was found that a very thin SiO 2 interlayer between Si crystallites and Er ions suppressed preferentially the Auger deexcitation to the carrier-mediated Er excitation. A thin SiO 2 interlayer was also effective to suppress the phonon-assisted energy backtransfer at high temperatures (so-called temperature quenching). This preferential suppression of the energy backflow (both Auger deexcitation and temperature quenching) by a thin oxide interlayer led to a strong room temperature Er-related emission at 1:54 mm in Er-doped porous silicon. The Er=SiO 2 =Si structure was also formed on a flat Si surface and quite the same result was obtained. The oxide interlayer thickness of B2 nm was found optimum to suppress the energy backflow sufficiently with only a slight decrease in the carrier-mediated excitation of Er ions. r 2002 Elsevier Science B.V. All rights reserved. Keywords: Er-doped Si; 1:54 mm luminescence; SiO 2 interlayer; Auger deexcitation 1. Introduction Er doping of Si and silicon-related materials have been extensively studied for the development of a light source or an optical amplifier at B1:54 mm ðB0:8 eVÞ in the Si-based optoelectro- nics [1–8]. Problems lying in the realization of an amplifier or a light emitting diode (LED) using an Er-doped silicon via carrier mediated excitation process are two energy backflows, i.e., temperature quenching and Auger deexcitation. The former is a phonon-assisted energy backflow from the excited Er 3þ ions to electrons captured at the so-called Er- related traps with a help of thermal phonons [9,10]. This process causes a large decrease in the 1:54 mm luminescence intensity with increasing *Corresponding author. Tel.: +81-424-43-5143; fax: +81- 424-43-5210. E-mail address: t-kimura@ee.uec.ac.jp (T. Kimura). 0022-2313/02/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0022-2313(02)00481-7