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Si nanocrystals as sensitizers for Er 3+ PL in SiO 2 M. Wojdak. Van der Waals - Zeeman Institute, University of Amsterdam. Valckenierstraat 65, NL-1018 XE Amsterdam, The Netherlands. Motivations. Why Er 3+ ?. Transition of l =1.53 m m is coincident with minimum loses in glass fibers.
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Si nanocrystals as sensitizers for Er3+ PL in SiO2M. Wojdak Van der Waals - Zeeman Institute,University of Amsterdam Valckenierstraat 65, NL-1018 XE Amsterdam, The Netherlands WZI seminar 16-04-2003
Motivations Why Er 3+ ? • Transition of l=1.53mm is coincident with minimum loses in glass fibers. • The lifetime of 1st excited state can be in the order of milliseconds (SiO2) or ms (Si) - possibility of population inversion Why silicon ? • Most common electronic material • Possibility of optical or electrical excitation of Er3+ • Integration of optoelectronics WZI seminar 16-04-2003
Erbium in silicon Ar+, Nd:YAG Excitation pathway in Si:Er • Optical or electrical excitation CB • Capture at erbium centers host Er3+ ion • Recombination of e-h pair • Er3+ excitation • Radiative decay VB • PL quenching at room temperature WZI seminar 16-04-2003
Erbium in SiO2 4F7/2 490 nm 2H11/2 520 nm 550 nm 4S3/2 4F9/2 650 nm 800 nm 4I9/2 980 nm 4I11/2 4I13/2 1535 nm 4I15/2 Er3+ • Thermal stability of emission • Only resonant excitation • Excitation cross section is extremely small 2 x 10-20 cm2 (W. Miniscalco J. Lightwave Technol.9, 234, 1991) WZI seminar 16-04-2003
SiO2:Si-nc,Er Si-nc Er3+ • Excitation cross section ~10-16 cm2 • Nonresonant excitation allowed • PL emission in room temperature (SiO2 host). WZI seminar 16-04-2003
Photoluminescence excitation spectra Si-nc Er3+ 4F7/2 490 nm 2H11/2 520 nm 550 nm 4S3/2 4F9/2 650 nm 800 nm 4I9/2 980 nm 4I11/2 4I13/2 1535 nm 4I15/2 Er3+ WZI seminar 16-04-2003
Comparison of PL intensity with Ar+ laser • SiO2:Er - excitation cross section ~10-20 cm2 • (W. Miniscalco J. Lightwave Technol.9, 234, 1991) • SiO2:Si-nc,Er - excitation cross section ~10-16 cm2 104 Ar+ laser, lexc=514.5nm ROOM TEMP. WZI seminar 16-04-2003
Samples • Photoluminescence spectra • Decay kinetics Si-nc Er3+ SiO2:Er,Si-nc SiO2:Er Er concentration: 2.2 × 1020 cm-3 Er concentration: 2.2 × 1020 cm-3 Si-nc concentration: 5 × 1017 - 1018 cm-3 diameter: 3.4 nm Samples were obtained in collaboration with the group of Prof. Francesco Priolo University of Catania WZI seminar 16-04-2003
Experimental setup Excitation of Photoluminescence (PL) Optical Parametric Oscillator (OPO) pumped by Nd:YAG sample • Variable wavelength • 430-650 nm (2.8-1.9 eV) • 780-2000 nm (1.6-0.6 eV) • Pulse Dt=5ns, 20Hz Ar+ laser • l=514.5 nm PL OPO or Ar+ Spectrometer • Triax 320mm Detectors • PMT • Germanium detector WZI seminar 16-04-2003
The model Approximations: • When sFDt <<1 Population obtained after Dt Photoluminescence emitted after the pulse is integrated in time: • When sFDt >>1 Rate equation • Laser pulse is much shorter than t WZI seminar 16-04-2003
Excitation flux dependence WZI seminar 16-04-2003
Excitation flux dependence WZI seminar 16-04-2003
Excitation flux dependence WZI seminar 16-04-2003
Excitation flux dependence WZI seminar 16-04-2003
Excitation flux dependence WZI seminar 16-04-2003
Excitation flux dependence s= 8.7 x 10-17 cm2 WZI seminar 16-04-2003
Excitation flux dependence WZI seminar 16-04-2003
Pulsed and continuous excitation l =520 nm 30 90 l= 514.5 nm l= 488 nm Pulsed Continuous WZI seminar 16-04-2003
Conclusion SiO2:Si-nc,Er ~33% ~0.2% ~66% WZI seminar 16-04-2003
Acknowledgements Financial support: NWO, ARL-ERO M. Forcales, M. Klik, N.Q. Vinh, I. Izeddin, and T. Gregorkiewicz,Van der Waals - Zeeman Institute, Valckenierstraat 65, NL-1018 XE Amsterdam, The NetherlandsO. B. Gusev,A.F.Ioffe Physicotechnical Institute, Russian Academy of Science, 194021 St. Petersburg, RussiaG. Franzò, D. Pacifici, F. Priolo,INFM and Dipartamento di Fisica e Astronomia, Università di Catania, Corso Italia 57, I-95129 Catania, ItalyF. IaconaCNR-IMETEM, Stradale Primosole 50, I-95121 Catania, Italy WZI seminar 16-04-2003