Electronic transport properties of Ti-impurity band in Si

© 2009 IOP Publishing Ltd. The authors would like to acknowledge the Nanotechnology and Surface Analysis Services of the Universidad de Vigo C.A.C.T.I. for SIMS measurements, the Center for Microanalysis of Materials of the Universidad Autónoma de Madrid for RBS measurements, C.A.I. de difracción de rayos X of the Universidad Complutense de Madrid for GIXRD measurements and C.A.I. de Técnicas Físicas of the Universidad Complutense de Madrid for ion implantation experiments. This work was made possible thanks to the FPI (Grant No BES-2005-7063) of the Spanish Ministry of Education and Science. This work was partially supported by the Projects NUMANCIA (No S-0505/ENE/000310) founded by the Comunidad de Madrid and GENESIS-FV (No CSD2006-00004) founded by the Spanish Consolider National Programme and by U.C.M.-C.A.M. under Grant CCG07-UCM/TIC-2804.
In this paper we show that pulsed laser melted high dose implantation of Ti in Si, above the Mott transition, produces an impurity band (IB) in this semiconductor. Using the van der Pauw method and Hall effect measurements we find strong laminated conductivity at the implanted layer and a temperature dependent decoupling between the Ti implanted layer (TIL) and the substrate. The conduction mechanism from the TIL to the substrate shows blocking characteristics that could be well explained through IB theory. Using the ATLAS code we can estimate the energetic position of the IB at 0.36 eV from the conduction band, the density of holes in this band which is closely related to the Ti atomic density and the hole mobility in this band. Band diagrams of the structure at low and high temperatures are also simulated in the ATLAS framework. The simulation obtained is fully coherent with experimental results.
FPI of the Spanish Ministry of Education and Science
Comunidad de Madrid
Spanish Consolider National Programme
U.C.M.-C.A.M.
Depto. de Estructura de la Materia, Física Térmica y Electrónica
Fac. de Ciencias Físicas
TRUE
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