Evidence for fast decay dynamics of the photoluminescence from Ge nanocrystals embedded in SiO2 |
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Authors: | PK Giri R Kesavamoorthy KGM Nair |
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Institution: | a Department of Physics, Indian Institute of Technology Guwahati, North Guwahati, Guwahati 781039, India b Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India |
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Abstract: | We have investigated the origin of room temperature photoluminescence from ion-beam synthesized Ge nanocrystals (NCs) embedded in SiO2 using steady state and time-resolved photoluminescence (PL) measurements. Ge NCs of diameter 4-13 nm were grown embedded in a thermally grown SiO2 layer by Ge+ ion implantation and subsequent annealing. Steady state PL spectra show a peak at ∼2.1 eV originating from Ge NCs and another peak at ∼2.3 eV arising from ion-beam induced defects in the SiO2 matrix. Time-resolved PL studies reveal double exponential decay dynamics on the nanoseconds time scale. The faster component of the decay with a time constant τ1∼3.1 ns is attributed to the nonradiative lifetime, since the time constant reduces with increasing defect density. The slower component with time constant τ2∼10 ns is attributed to radiative recombination at the Ge NCs. Our results are in close agreement with the theoretically predicted radiative lifetime for small Ge NCs. |
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Keywords: | 78 47 +p 78 67 Bf 61 46 +w 78 55 &minus m |
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