Influence of substrate material on spectral properties and thermal quenching

Kateřina Dragounová – Tibor Ižák – Alexander Kromka – Zdeněk Potůček
– Zdeněk Bryknar – Štěpán Potocký

   Nanocrystalline diamond films with bright photoluminescence of silicon-vacancy colour centres have been grown using a microwave plasma enhanced CVD technique. Influence of substrate material (quartz, Al₂O₃, Mo and Si) on a reproducible fabrication of diamond thin films with Si-V optical centres is presented. Film quality and morphology are characterised by Raman spectroscopy and SEM technique. The SEM shows well faceted diamond grains with sizes from 170 to 300 nm. The diamond peak is confirmed in Raman spectra for all samples. In the case of the quartz substrate, a redshift of the diamond peak is observed (∼ 3.5/cm^-1) due to tension in the diamond film. The steady-state photoluminescence intensity was measured in the temperature range from 11 K to 300 K. All spectra consist of broad emission band with a maximum near 600 nm and of a sharp zero phonon line at the vicinity of 738 nm corresponding to Si-V centres that is accompanied with phonon sideband peaking at 757 nm. Activation energies for the thermal quenching of Si-V centre photoluminescence were determined and effect of substrate on photoluminescence properties is discussed too.

Keywords: diamond, Si-V centre, photoluminescence, microwave-plasma enhanced CVD, activation energy

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