title: In situ gas-phase hydrosilylation of plasma-synthesized silicon nanocrystals.
abstract: Surface passivation of semiconductor nanocrystals (NCs) is critical in enabling their utilization in novel optoelectronic devices, solar cells, and biological and chemical sensors. Compared to the extensively used liquid-phase NC synthesis and passivation techniques, gas-phase routes provide the unique opportunity for in situ passivation of semiconductor NCs. Herein, we present a method for in situ gas-phase organic functionalization of plasma-synthesized, H-terminated silicon (Si) NCs. Using real-time in situ attenuated total reflection Fourier transform IR spectroscopy, we have studied the surface reactions during hydrosilylation of Si NCs at 160 °C. First, we show that, during gas-phase hydrosilylation of Si NCs using styrene (1-alkene) and acetylene (alkyne), the reaction pathways of the alkenes and alkynes chemisorbing onto surface SiH(x) (x = 1-3) species are different. Second, utilizing this difference in reactivity, we demonstrate a novel pathway to enhance the surface ligand passivation of Si NCs via in situ gas-phase hydrosilylation using the combination of a short-chain alkyne (acetylene) and a long-chain 1-alkene (styrene). The quality of surface passivation is further validated through IR and photoluminescence measurements of Si NCs exposed to air.
authors.affiliation: Department of Chemical Engineering and §Division of Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
authors.forename: Bhavin N
authors.initials: BN
authors.lastname: Jariwala
authors.forename: Oliver S
authors.initials: OS
authors.lastname: Dewey
authors.forename: Paul
authors.initials: P
authors.lastname: Stradins
authors.forename: Cristian V
authors.initials: CV
authors.lastname: Ciobanu
authors.forename: Sumit
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D000114:Acetylene / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry; D005740:Gases / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D000475:Alkenes; D005740:Gases; D000114:Acetylene; D012825:Silicon