Sub-bandgap absorption in Ti implanted Si over the Mott limit
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2011
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American Institute of Physics
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Abstract
We have analyzed the structural and optical properties of Si implanted with very high Ti doses and subsequently pulsed-laser melted (PLM). After PLM, all samples exhibit an abrupt and roughly uniform, box-shaped Ti profile, with a concentration around 2 x 10(20) cm(-3), which is well above the Mott limit, within a 150 nm thick layer. Samples PLM-annealed at the highest energy density (1.8 J/cm(2)) exhibit good lattice reconstruction. Independent of the annealing energy density, in all of the samples we observe strong sub-bandgap absorption, with absorption coefficient values between 4 x 10(3) and 10(4) cm(-1). These results are explained in terms of the formation of an intermediate band (IB) originated from the Ti deep levels.
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© 2011 American Institute of Physics. The authors would like to acknowledge the Nanotechnology and Surface Analysis Services of the Universidad de Vigo C.A.C.T.I. for ToF-SIMS measurements, C.A.I.s de Técnicas Físicas and spectroscopía of the Universidad Complutense de Madrid for ion implantation experiments and FTIR measurement facilities and Dr. J. Herrero (CIEMAT) for UV-VIS-IR measurements facilities. This work was partially supported by the Projects GENESIS-FV (Grant No. CSD2006-0004) funded by the Spanish Consolider National Programme, NUMANCIA II (Grant No. S-2009/ENE-1477) funded by the Regional Government of Comunidad de Madrid.