Plasmon-Enhanced Photoluminescence of Si Nanocrystals Embedded in Silicon Rich Oxynitride Thin Film

Zoltán Édes Institute of Physical Engineering, Brno University of Technology, Brno, Czech Republic Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic Vlastimil Křápek Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic Jiří Spousta Institute of Physical Engineering, Brno University of Technology, Brno, Czech Republic Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic Peter Varga Institute of Physical Engineering, Brno University of Technology, Brno, Czech Republic Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic Tomáš Šikola Institute of Physical Engineering, Brno University of Technology, Brno, Czech Republic Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic

Enhancement of photoluminescence using metallic nanoparticles is a well known application of plasmonics and was intensively studied over the past decade. Luminescence of given semiconducting bulk materials or quantum dots and flourescent molecules can be strongly enhanced and also quenched due to coupling to metallic nanostructures in their close proximity [1].

In our work this effect was studied using silicon rich oxynitride (SRON), which exhibits interesting luminescent properties. Without its annealing, only a weak visible photoluminescence is observable, mostly originating from defects of the material. However, high temperature annealing (1100°C) gives rise to the creation of luminescent Si nanocrystals inside the material [2]. These nanocrystals exhibit photoluminescence from the visible to the near infrared region, depending on the annealing temperature and time. For our experiments the 20nm-thick SRON layer grown on Si substrates using plasma assisted chemical vapor deposition was selected. Afterwards, an array of cylindrical gold nanoparticles (antennas of different size and spacing) were fabricated on top of the SRON layer by electron beam lithography to study the enhanced photoluminescence. Furthermore, an Al₂O₃layer of various thicknesses was prepared using atomic layer deposition (ALD), to find an ideal separation between the thin SRON layer and the gold nanoparticles [3]. The photoluminescence effect on these structures was studied using a confocal Raman & fluorescence setup NTEGRA Spectra (NT MDT).

Using a commercial FDTD software (Lumerical), numerical calculations of the antenna electromagnetic field and enhancement of the emission effect were carried out to optimize the photoluminescence experiments.

References:

[1] Novotny L. et al., Physical Review Letters 96, 113002 (2006).

[2] Tewary A et al., Applied Physics Letters 88, 093114 (2006)

[3] Gerard D. et al., Scientific Reports, 2672 (2013).

zoltan.edes@ceitec.vutbr.cz