~:~ ': ~ :', ELSEVIER Microelectronic Engineering 36 (1997) 107-110 MICROrJ~I'ROI¢/C r-NGilU:Iglt~G Blue and violet photoluminescence from high-dose Si ÷- and Ge÷-implanted silicon dioxide layers L. Rebohlea, I. E. Tyschenko b, H. Fr6b¢, K. Leo ~, R. A. Yankov*, J. yon Borany ~, G. A. Kachurinb and W. Skomp# Institut fiir Ionenstrahlphysik und Materialforschung, Forschungszentrum Rossendoff e.V., POB 510119, D-01314 Dresden, Germany: Tel. :+49-351-2602068; Fax:+49-351-2603411; e-mail: rebohle@,fz-rossendorf.de blnstitut fiir Halbleiterphysik, Russische Akademie der Wissenschaflen, Nowosihirsk, Russia qnstitut fiir Angewandte PhotophysiL Technische Universi~'t Dresden, Mommsenstr. 13, D-01062 Dresden, Germany Strong blue (around 470 nm) and violet (around 395 nm) photoluminescence (PL) at room temperature (RT) was obtained from thermally-grown SiO2 films on crystalline Si implanted with Si + and Ge + ions, respectively Photoluminescence excitation (PLE) spectroscopy measurements indicate maximum PL at 248 nm (for Si +) and 242 nm (for Ge+). The blue PL intensity was investigated as a function of subsequent furnace and flash lamp annealing. The results obtained are interpreted in terms of the excess atoms introduced in the SiO2 network. 1. INTRODUCTION SiO2 is of great importance as a passivating and insulating material for the production of electronic devices and belongs to the most widely investigated compounds in science and technology. Recently it has become clear that in a number of cases impurity-rich SiO2 layers possess luminescing properties. Since the discovery of PL from porous silicon at RT, this topic has attracted increasing interest for the development of Si-based optoelectronic devices. One of the most promising methods of producing luminescence centres in SiO2 films is the formation of non-stoichiometric layers using Si- or Ge-implantation followed by annealing. The advantages of this method are the precise control over the number and distribution of the implanted ions and its compatibility with current Si technology. Silicon-rich SiCh layers have been found to emit red PL [1,2]. Recent studies have demonstrated the possibility of achieving blue PL (410-460 nm) from silicon-rich SiO2 layers [3-5]. In order to obtain consistent information on the nature of blue and violet PL from Ge +-, Ar+- and Si+-implanted SiCh, we have investigated the influence of both the implanted species and annealing conditions on the PL efficiency. 2. EXPERIMENTAL Thermally-grown, 500 nm thick SiO2 films on (100) n-type Si wafers were implanted with Si +, Ge + and Ar + using a beam current density in the range of 0.5 to 1.0 gA cm"2. More specifically, Si + ions were implanted first at an energy of 200 keV to a dose of 3.0x1016 cm"2 and then at 100 keV to a dose of 1.gxl0 ~6 cm"2. Double-energy implantation was similarly performed for Ge + at 350 keV and 200 keV tO doges of 2.8x1016 cm "2 and 1.8x10 ~6 cm"2, respectively. Ar+ ions were implanted to doses of 3.0x1016 cm"2 (250 keV) and 1.5x1016 cm"2 (170 keV). The implant energies and doses were chosen in such a way as to achieve one and the same concentration and depth location of the implanted ions. According to TRIM calculations, these distributions would be nearly fiat-topped within a depth region of 100 to 400 nm below the oxide surface. The substrate temperature during implantation was kept between -120°C and -150°C by mounting the wafers on a LN2-cooled stage, After implantation the wafers were cut into segments and annealed using two different procedures. One set of Si-implanted samples was heat-treated by furnace annealing (FA) for 30 rain at temperatures ranging from 300°C to 700°C, whereas another one was subjected to flash-lamp 0167-9317/97/$17.00 © Elsevier Science B.V. All rights reserved. PII: S0167-9317(97)00026-9