Enhancing the luminescence efficiency of silicon-nanocrystals by interaction with H + ions

• Published in: Physical chemistry chemical physics : PCCP Vol. 20; no. 15; pp. 10445 - 10449
• Main Authors: Cannas, Marco, Camarda, Pietro, Vaccaro, Lavinia, Amato, Francesco, Messina, Fabrizio, Fiore, Tiziana, Li Vigni, Maria
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 2018
• Subjects: Chemical synthesis; Decay rate; Defects; Electron paramagnetic resonance; Emission; Excitation spectra; Excitons; Interlayers; Laser ablation; Nanocrystals; Photoluminescence; Pulsed lasers; Quantum efficiency; Radiative recombination; Silicon dioxide
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c8cp00616d

The emission of silicon nanocrystals (Si-NCs), synthesized by pulsed laser ablation in water, was investigated on varying the pH of the solution. These samples emit μs decaying orange photoluminescence (PL) associated with radiative recombination of quantum-confined excitons. Time-resolved spectra reveal that both the PL intensity and the lifetime increase by a factor of ∼20 when the pH decreases from 10 to 1 thus indicating that the emission quantum efficiency increases by inhibiting nonradiative decay rates. Infrared (IR) absorption and electron paramagnetic resonance (EPR) experiments allow addressing the origin of defects on which the excitons nonradiatively recombine. The linear correlation between the PL and the growth of SiH groups demonstrates that H+ ions passivate the nonradiative defects that are located in the interlayer between the Si-NC core and the amorphous SiO2 shell.