17th International Conference on Ion Beam Modification of Materials

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Electro- and photoluminescence induced by Ge nanocrystals obtained by hot ion implantation into SiO2

Moni Behar*, Felipe L Bregolin, Uilson S Sias, Lars Rebohle, and Wolfgang Skorupa

oral presentation: 2010-08-23 02:50 PM – 03:10 PM
Last modified: 2010-06-13


Commonly photo (PL) and electroluminiscence (EL) from Ge nanocrystals (GE NCs) has been obtained by room temperature (RT) Ge implantation into SiO2 matrix followed by a high temperature anneal. In this way two bands have been obtained, one centered at around 310 nm and the second at 390 nm with much higher PL and EL yields. In the present work we have used a novel experimental approach: we have performed the Ge implantation at high temperature (350°C) and followed by a higher temperature anneal at 900°C in order to grow the Ge NCs. The implantations were performed at 120 keV into a 200 nm SiO2 substrate at two different fluences: 0.5 and 1x1016 Ge/cm2 respectively. In what follows we are only going to refer to the results obtained for the 390 nm band. The PL studies performed at RT, using a Xe lamp (λexc = 240 nm) as excitation source have shown two striking results. When the samples were implanted at 350°C at a fluence of Φ=1x1016Ge/cm2 the PL yield was four times larger as compared with the one obtained with the RT implanted samples. Moreover if the implanted fluence was reduced at 0.5x1016Ge/cm2 an additional factor of three was obtained in the PL yield. Concerning the EL measurements they also were done at RT. The spectra were obtained under a constant current injection density of 320 μA/cm2. The first observed feature is that the intensities of the hot implanted samples are around 30% lower than the ones obtained by RT implantation. The second feature is that the hot implanted samples show an electrical stability that is three times larger than the one obtained by the RT implants. Finally by increasing the implantation fluence a blue shift is observed in the 390 nm band. All these observations are explained on the basis of the Ge NCs distribution as obtained from TEM measurements.

Author(s) affiliation:
Moni Behar*, Universidade Federal do Rio Grande do Sul, Brazil
Felipe L Bregolin, Universidade Federal do Rio Grande do Sul, Brazil
Uilson S Sias, Instituto Federal de Educação, Ciência e Tecnologia, Brazil
Lars Rebohle, Forschungszentrum Dresden-Rossendorf (FZD), Germany
Wolfgang Skorupa, Forschungszentrum Dresden-Rossendorf (FZD), Germany

*presenting author
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