Taming non-radiative recombination in Si nanocrystals interlinked in a porous network

Rihan Wu, Elida Nekovic, Jack Collins, Catherine Storey, Leigh Canham, Miguel Navarro-Cia, Andre Kaplan

Research output: Contribution to journalArticlepeer-review

Abstract

A range of the distinctive physical properties, comprising high surface-to-volume ratio, possibility to achieve mechanical and chemical stability after a tailored treatment, controlled quantum confinement and the room-temperature photoluminescence, combined with mass production capabilities offer porous silicon unmatched capabilities required for the development of electro-optical devices. Yet, the mechanism of the charge carrier dynamics remains poorly controlled and understood. In particular, non-radiative recombination, often the main process of the excited carrier’s decay, has not been adequately comprehended to this day. Here we show, that the recombination mechanism critically depends on the composition of surface passivation. That is, hydrogen passivated material exhibits Shockley–Read–Hall type of decay, while for oxidised surfaces, it proceeds by two orders of magnitude faster and exclusively through the Auger process. Moreover, it is possible to control the source of recombination in the same sample by applying a cyclic sequence of hydrogenation–oxidation–hydrogenation processes, and, consequently switching on-demand between Shockley–Read–Hall and Auger recombinations. Remarkably, irregardless of the recombination mechanism, the rate constant scales inversely with the average volume of individual silicon nanocrystals contained in the material. Thus, the type of the non-radiative recombination is established by the composition of the passivation, while its rate depends on the degree of the charge carriers’ quantum confinement.
Original languageEnglish
Pages (from-to)13519–13526
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume24
Issue number22
Early online date13 May 2022
DOIs
Publication statusPublished - 14 Jun 2022

Keywords

  • Nanocrystals
  • Charge carrier dynamics
  • porous silicon

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Fingerprint

Dive into the research topics of 'Taming non-radiative recombination in Si nanocrystals interlinked in a porous network'. Together they form a unique fingerprint.

Cite this