Please cite this article in press as: J. Bak-Misiuk, et al., Mater. Sci. Eng. B (2008), doi:10.1016/j.mseb.2008.06.034 ARTICLE IN PRESS G Model MSB-11763; No. of Pages 4 Materials Science and Engineering B xxx (2008) xxx–xxx Contents lists available at ScienceDirect Materials Science and Engineering B journal homepage: www.elsevier.com/locate/mseb Effect of processing on microstructure of Si:Mn J. Bak-Misiuk a,∗ , A. Misiuk b , P. Romanowski a , A. Barcz a,b , R. Jakiela a , E. Dynowska a , J.Z. Domagala a , W. Caliebe c a Institute of Physics, PAS, SLI. 3, Al. Lotnikow 32/46, PL-02668 Warsaw, Poland b Institute of Electron Technology, Al. Lotnikow 46, PL-02668 Warsaw, Poland c HASYLAB at DESY, Notkerstr. 85, D-22603 Hamburg, Germany article info Article history: Received 24 April 2008 Received in revised form 23 May 2008 Accepted 23 June 2008 Keywords: Si Mn Interstitial oxygen Implantation High pressure Annealing Spintronics abstract Effect of processing of Si:Mn at up to 1270 K (HT) under enhanced hydrostatic pressure (HP, up to 1.1 GPa) for 1h on its microstructure has been investigated by X-ray and SIMS methods. Si:Mn was prepared by implantation at 610K of Mn + ions (dose 1 × 10 16 cm -2 , energy 160 keV) into (0 0 1) oriented Czochralski (Cz-Si) or Floating zone (Fz-Si) silicon with interstitial oxygen concentration, c o = 1.5 × 10 17 cm -3 (Fz-Si) or 9 × 10 17 cm -3 (Cz-Si). The defect structure of Si:Mn depends on c o , HT and HP. The intensity of X-ray diffrac- tion peaks originating from the ferromagnetic Mn 4 Si 7 phase (with the lattice parameters a = 0.5525 nm and c = 1.7463 nm) increases with HT, up to 1070 K. Markedly shifted Mn atom concentration towards the surface is observed after processing of Si:Mn at ≥1000 K, especially under 10 5 Pa. Processing at 1270 K results in the decreased content of Mn 4 Si 7 ; Mn diffusivity decreases with HP. Oxygen gettering within the implantation-disturbed area has been stated. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Rapid development of spintronics is observed recently. Diluted magnetic semiconductors (DMS) are promising for electronic devices involving spin-based functionality. Compounds III–V, II–VI and Si-based semiconductors doped with transition metals are usually considered as promising for producing DMS. Considerable effort has been done to prepare room temperature ferromagnetic III–V semiconductors (e.g. [1–3]). However, no satisfying material has been fabricated as so far. It has been demonstrated, that ferro- magnetically ordered precipitates are produced in the Mn-doped III–V semiconductors, yielding multi-phase materials [4]. Silicon-based DMS are preferred spintronic materials due to existing technology widely used in Si-based microelectronics and wide availability of high quality Si single crystals. Based on the Zener model, Dietl et al. predicted a carrier-mediated ferromag- netism for silicon doped with 5% Mn [2]. Zhang et al. [5] reported the Mn 0.05 Si 0.95 alloy with Curie temperature (T C ) of about 400 K; such epitaxially grown films indicate anomalous Hall effect around 70 K, suggesting internal magnetization of local Mn spins [6]. Ion implantation has also been utilized to achieve ferro- magnetism in semiconductors. Ferromagnetic ordering in silicon ∗ Corresponding author. Tel.: +48 22 8436034; fax: +48 22 8436034. E-mail address: bakmi@ifpan.edu.pl (J. Bak-Misiuk). implanted with Mn + ions (Si:Mn) has been reported recently [7,8]. This ordering is evidently related to the microstructure of Mn- enriched near-surface layer of the implanted material. It has been stated that T C exceeds 400 K in Si:Mn subjected to rapid ther- mal annealing at 1070 K [7]. Ferromagnetic properties of annealed Si:Mn have been attributed to a formation of MnSi 1.7 nanoparti- cles [8]. Not only processing temperature (HT), but also enhanced hydrostatic pressure (HP) applied at processing affect structural and magnetic properties of Si-based DMS [9,10]. The aim of this work is the determination of the effect of pro- cessing conditions on the structure of Si:Mn, prepared from single crystalline Si with different concentration (c o ) of interstitial oxygen. 2. Experimental Floating zone (Fz-Si) and Czochralski (Cz-Si) grown silicon sam- ples, 0 0 1 oriented, with c o = 1.5 × 10 17 cm -3 and 9 × 10 17 cm -3 , respectively, were implanted with Mn + at energy 160 keV to a dose D =1 × 10 16 cm -2 , at substrate temperature, T S = 610 K. Projected range (R p ) of Mn + ions was equal to 140 ± 50 nm. Si:Mn was next processed for 1 h at HT up to 1270 K under HP = 10 5 Pa or 1.1GPa. Phase analysis of the near-surface Si:Mn layers was performed using synchrotron radiation source at the W1 beamline of DESY-HASYLAB. To investigate the phase com- position of the thin polycrystalline layers created at processing, measurements were done using coplanar 2 scan in the grazing 0921-5107/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2008.06.034