Dohnalová, Katerina

Huang, Chia-Ching

Nie, Hui

Paulusse, Jos M.J.

Wilbrink, Jonathan

English

Quantum confinement effects in silicon nanostructures have been studied over the past 3 decades [1], with aim to convert silicon into direct bandgap-like semiconductor for applications as efficient light emitters, even amplifiers and lasers. We have shown that slightly electronegative ligands on the surface of silicon quantum dot (Si-QD) and/or varying electrostatic field from the environment manipulates the electronic density inside the Si-QD’s core, ultimately resulting in an indirect-to-direct bandgap conversion [2,3]. To test the role of charge distribution induced by ligands and environment experimentally, we synthesize colloidal Si-QDs capped by butyl chains using oxygen-free wet chemical method [3] and introduce two terminations, amine (-NH2) and carboxylic acid (-COOH). Si-QDs are dispersed in aqueous solutions of varying pH. The push-pull effect on the electronic wave-functions translates into changes in band-gap (emission spectrum and absorption band-edge) and emission lifetime. Results are interpreted and discussed within the frame of our theoretical simulations by tight binding and DFT

University of Twente Research Information

 Role of surface charge distribution on band-structure and optical properties of silicon nanocrystals  Authors : Chia-Ching Huang(1), Hui Nie(2), Jonathan Wilbrink(2), Jos MJ Paulusse(2), Katerina Dohnalova(1) Affiliations : (1) Institute of Physics, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, the Netherlands; (2) MIRA Institute, University of Twente, P.O. Box 217, 7500 AE, Enschede, the Netherlands Resume : Quantum confinement effects in silicon nanostructures have been studied over the past 3 decades [1], with aim to convert silicon into direct bandgap-like semiconductor for applications as efficient light emitters, even amplifiers and lasers. We have shown that slightly electronegative ligands on the surface of silicon quantum dot (Si-QD) and/or varying electrostatic field from the environment manipulates the electronic density inside the Si-QD’s core, ultimately resulting in an indirect-to-direct bandgap conversion [2,3]. To test the role of charge distribution induced by ligands and environment experimentally, we synthesize colloidal Si-QDs capped by butyl chains using oxygen-free wet chemical method [3] and introduce two terminations, amine (-NH2) and carboxylic acid (-COOH). Si-QDs are dispersed in aqueous solutions of varying pH. The push-pull effect on the electronic wave-functions translates into changes in band-gap (emission spectrum and absorption band-edge) and emission lifetime. Results are interpreted and discussed within the frame of our theoretical simulations by tight binding and DFT. [1] K. Dohnalova et al., J. Phys.: Condens. Matter 26, 173201 (2014) [2] A. N. Podubny and K. Dohnalova, Phys. Rev. B 90, 245439 (2014) [3] K. Dohnalova et al., Light: Sci. and Appl. 2, e47 (2013)  

Role of surface charge distribution on band-structure and optical properties of silicon nanocrystals

https://ris.utwente.nl/ws/files/145891469/Huang2017role.pdf

Role of surface charge distribution on band-structure and optical properties of silicon nanocrystals

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