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Microwave annealing (MWA) processes were used for the first time to obtain Ti supersaturated Si. High Ti doses were ion implanted on Si substrates and subsequently MWA processed to recrystallize the amorphous layer. The resulting layers were monocrystalline with a high density of defects. Ti depth profiles indicate that diffusion is avoided once recrystallization is produced. Finally, the electronic transport properties measurements point to a decoupling effect between the Si:Ti layer and the substrate. The implanted layer present also a shallow donor and very high Hall mobility., Universidad Complutense de Madrid, European Regional Development Fund (Unión Europea), Ministerio de Ciencia e Innovación (España), European Social Found (Unión Europea), Ministry of Education (Arabia Saudita), Consejo Nacional de Humanidades, Ciencias y Tecnologías (México), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2016 IOP Publishing Ltd. The authors would like to acknowledge the C A I de Técnicas Físicas of the Universidad Complutense de Madrid for the ion implantations and metallic evaporations, the Nanotechnology and Surface Analysis Services of the Universidad de Vigo C.A.C.T.I. for ToF-SIMS measurements and Dr J P González García from CIEMAT for reflectance measurements. Research by E García-Hemme was supported by a PICATA predoctoral fellowship of the Moncloa Campus of International Excellence (UCM-UPM). J Olea acknowledges financial support from the MICINN within the program Juan de la Cierva (JCI-2011-10402), under which this research was undertaken. D Pastor acknowledges the financial support to the grant EX-2010-0662 from the Spanish Science Ministry. This work was partially supported by the Spanish MINECO (Economic and Competitiviness Ministery) through grant TEC 2013-41730-R. The authors acknowledge the financial support from la Comunidad de Madrid throughout the funding of the project, MADRID-PV (S2013/MAE-2780)., Silicon samples were implanted with high Ti doses and subsequently processed with the pulsed-laser melting technique. The electronic transport properties in the 15–300 K range and the room temperature spectral photoresponse at energies over the bandgap were measured. Samples with Ti concentration below the insulator-metal (I-M) transition limit showed a progressive reduction of the carrier lifetime in the implanted layer as Ti dose is increased. However, when the Ti concentration exceeded this limit, an extraordinary recovery of the photoresponse was measured. This result supports the theory of intermediate band materials and is of utmost relevance for photovoltaic cells and Si-based detectors., Ministerio de Economía y Competitividad (MINECO), Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Campus de Excelencia Internacional Moncloa UCM-UPM, PICATA Programa Internacional de Captación de Talento Convocatorias Campus Moncloa, Ayudas para contratos Juan de la Cierva (MICINN), Ministerio de Ciencia y Tecnología (MCYT), España, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Se deposita la versión posprint del artículo, In the scope of supersaturated semiconductors for infrared detectors, we implanted Si samples with Ti at high doses and processed them by rapid thermal annealing (RTA) to recover the crystal quality. Also, for comparative purposes, some samples were processed by pulsed-laser melting. We measured the electronic transport properties at variable temperatures and analyzed the results. The results indicate that, for RTA samples, surface layers with a high Ti concentration have negligible conductivity due to defects. In contrast, the implantation tail region has measurable conductivity due to very high electron mobility. This region shows the activation of a very shallow donor and a deep donor level. While deep levels have been previously reported for Ti in Si, such a shallow level has never been measured, and we suggest that it originates from Ti-Si complexes. Finally, a decoupling effect between the implanted layer and the substrate seems to be present, and a bilayer model is applied to fit the measured properties. The fitted parameters follow the Meyer–Neldel rule. The role of the implantation tails in Si supersaturated with Ti is revealed in this work., Comunidad de Madrid, ERDF Funds - MICINN, European Social Fund (ESF), Ministerio de Ciencia e Innovación (España), Mexican grants program CONACyT, Ministry of Education in the Kingdom of Saudi Arabia, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

"Authors would like to acknowledge C.A.I. de Técnicas Físicas of theUniversidad Complutense de Madrid for ion implantation, RTA andJoule and e‐beam evaporations, and the technical and human supportprovided by Facility of Analysis and Characterization of Solids andSurfaces of SAIUEx (financed by UEX, Junta de Extremadura, MICINN,FEDER, and FSE). This work was partially supported by ProjectMADRID‐PV (grant no. P2013/MAE‐2780) funded by the Comunidadde Madrid, by the Spanish MINECO (Ministerio de Economía yCompetitividad) under grants TEC 2013‐41730‐R and TEC 2015‐69916‐C2‐1‐R, and by the Universidad Complutense de Madrid(Programa de Financiación de Grupos de Investigación UCM–BancoSantander) under grant 910173‐2014. The work of D. Montero wassupported by the Spanish MINECO under contract BES‐2014‐067585. J. Solis from the Instituto de Optica is acknowledged for help-ful discussions.", Photovoltaic solar cells based on the intermediate band (IB) concept could greatly enhance theefficiency of future devices. We have analyzed the electrical and photoconductivity propertiesof GaP supersaturated with Ti to assess its suitability for IB solar cells. GaP:Ti was obtained byion implantation followed by pulsed‐laser melting (PLM) using an ArF excimer laser. It was foundthat PLM energy densities between 0.35 and 0.55 J/cm2produced a good recovery of thecrystalline structure of GaP (both unimplanted and implanted with Ti), as evidenced by highmobility measured values (close to the reference GaP). Outside this energy density window,the PLM failed to recover the crystalline structure producing a low mobility layer that iselectrically isolated from the substrate. Spectral photoconductivity measurements wereperformed by using the van der Pauw set up. For GaP:Ti a significant enhancement of theconductivity was observed when illuminating the sample with photon energies below 2.26 eV,suggesting that this photoconductivity is related to the presence of Ti in a concentration highenough to form an IB within the GaP bandgap. The position of the IB was estimated to be around1.1 eV from the conduction band or the valence band of GaP, which would lead to maximumtheoretical efficiencies of 25% to 35% for a selective absorption coefficients scenario and higherfor an overlapping scenario, Comunidad de Madrid, Ministerio de Economía y Competitividad, Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Photovoltaic solar cells based on the intermediate band (IB) concept could greatly enhance the efficiency of future devices. We have analyzed the electrical and photoconductivity properties of GaP supersaturated with Ti to assess its suitability for IB solar cells. GaP:Ti was obtained by ion implantation followed by pulsed-laser melting (PLM) using an ArF excimer laser. It was found that PLM energy densities between 0.35 and 0.55 J/cm produced a good recovery of the crystalline structure of GaP (both unimplanted and implanted with Ti), as evidenced by high mobility measured values (close to the reference GaP). Outside this energy density window, the PLM failed to recover the crystalline structure producing a low mobility layer that is electrically isolated from the substrate. Spectral photoconductivity measurements were performed by using the van der Pauw set up. For GaP:Ti a significant enhancement of the conductivity was observed when illuminating the sample with photon energies below 2.26 eV, suggesting that this photoconductivity is related to the presence of Ti in a concentration high enough to form an IB within the GaP bandgap. The position of the IB was estimated to be around 1.1 eV from the conduction band or the valence band of GaP, which would lead to maximum theoretical efficiencies of 25% to 35% for a selective absorption coefficients scenario and higher for an overlapping scenario.