ISSN 1063-7842, Technical Physics, 2008, Vol. 53, No. 8, pp. 1070–1073. © Pleiades Publishing, Ltd., 2008. Original Russian Text © A.L. Stepanov, V.F. Valeev, V.I. Nuzhdin, R.I. Khaibullin, Yu.N. Osin, I.A. Faizrakhmanov, 2008, published in Zhurnal Tekhnicheskoœ Fiziki, 2008, Vol. 78, No. 8, pp. 112–115. 1070 Oxide semiconductors, in particular, titanium diox- ide TiO 2 , doped by iron group transition metal atoms have attracted considerable interest. Such composite materials are promising for ferromagnetism at room tem- perature [1] and photocatalysis [2]. Ion implantation (II) is an effective method for doping TiO 2 [2–6]. Implantation at low and medium energies (10–100 keV) is of particular interest for this purpose, since it results in ultrathin composite layers. One of the important and challenging experimental II problems is to determine the geometri- cal parameters of the depth profiles of the impurity con- centration in a target. With such data, researchers can find the implantation dose range characteristic of the formation of metallic nanoparticles in an implanted layer, the modified-layer thickness, and the limiting implanted impurity concentration to be reached under given II conditions. Since all these parameters are important, the prob- lem is solved via computer simulation of the decelera- tion of accelerated ions in a target. However, the avail- able tables of calculated depth profile parameters, which are mainly composed for the II of single-compo- nent materials (Si, Ge, Cu, etc.), and software like TRIM (Transport of Ions in Matter) or SRIM (Stopping and Range of Ions in Solids) [7] cannot be applied for medium and high II doses (>10 15 ions/cm 2 ), since they do not take into account the scattering of the surface and the irradiation-induced change in the elemental composition of the implanted layer. The depth profiles calculated by these computer programs and based on the Monte Carlo statistical distribution differ substan- tially from the real depth profiles of medium-energy ions. As an example, Fig. 1 shows the experimental depth profile of implanted 40-keV cobalt ions in the near-sur- face layer of TiO 2 measured by X-ray photoelectron spectroscopy in combination with layer-by-layer ion sputtering (Ar 2+ , 2 keV) [6]. The implanted impurity concentration is seen to be maximal near the surface. The asymmetric shape of the depth profile of cobalt atoms does not correspond to the symmetric Gaussian profile calculated upon TRIM simulation using the SRIM-2006 computer program for the given type of ion, matrix, and II conditions (Fig. 2), since this simu- lation does not take into account a change in the ele- mental composition of the implanted layer and ion Depth Profiles of Transition-Metal Atoms Implanted in a Titanium Dioxide Matrix at Medium Energies A. L. Stepanov a, b , V. F. Valeev b , V. I. Nuzhdin b , R. I. Khaibullin b , Yu. N. Osin b , and I. A. Faizrakhmanov b a Laser Zentrum Hannover, Hannover, 30419 Germany b Zavoiskii Physicotechnical Institute, Russian Academy of Sciences, Sibirskii trakt 10/7, Kazan 29, 420029 Tatarstan, Russia e-mail: a.stepanov@lzh.de, anstep@kfti.knc.ru Received October 22, 2007 Abstract—The depth profiles of 40-keV cobalt, chromium, and copper ions implanted into a titanium dioxide matrix at doses of 10 16 –10 17 ions/cm 2 are simulated with the DYNA software package. Its algorithm is based on the effects of pair collisions of introduced ions with substrate atoms, which result in a dynamic change in the elemental composition of the near-surface layer in the irradiated material, and takes into account surface sputtering. The results obtained are compared with the standard statistical distribution calculated by the TRIM algorithm. PACS numbers: 61.70.Tm, 61.80.Mk, 79.20.Nc DOI: 10.1134/S106378420808015X SURFACE, ELECTRON AND ION EMISSION 60 40 20 0 Depth, nm 20 40 Concentration, at % Fig. 1. Experimental depth profile of 40-keV cobalt ions implanted into TiO 2 at a dose of 1.5 × 10 17 ions/cm 2 . This pro- file was measured by X-ray photoelectron spectroscopy [6].