Photochemical Assembly of Gold Nanoparticle Arrays Covalently Attached to Silicon Surface Assisted by Localized Plasmon in the Nanoparticles

Abstract

It is essential to immobilize gold nanoparticles (AuNPs) firmly onto a certain substrate in a closely packed manner to apply plasmonic functions of AuNP in photonic/electronic devices. AuNP-Si systems are of particular interest for the integration of plasmonics to semiconductor electronics. Here we report on the arrangement of AuNPs into a 2-D array that was covalently bonded to a Si substrate without surface oxide. This process was achieved by simply irradiating visible light to a hydogen-terminated Si substrate immersed in a solution of AuNPs covered with a self-assembled monolayer (SAM) of 11-mercaptoundecene (MUD). These MUD-AuNPs were attached to the substrate by forming Si–C bonds as a result of the photochemical reaction between Si–H groups on the substrate and vinyl groups of the MUD-SAMs. The reaction proceeded most effectively at a wavelength band around 520 nm adjusted to the plasmonic resonance peak of the MUD-AuNPs(20 nm in diameter)/toluene solution centered at 535 nm, demonstrating that the photochemical reaction was assisted by localized surface plasmon, which allowed the AuNPs to be photon collectors.

Chemical conversion of self-assembled hexadecyl monolayers with active oxygen species generated by vacuum ultraviolet irradiation in an atmospheric environment

“…[3][4][5] The lack of a silicon dioxide (SiO 2 ) interfacial layer 6,7 enables electron transmission to the substrate via SAMs. 16 Recent studies on the photoirradiation of both polymers and SAMs indicated that irradiation by vacuum ultraviolet (VUV) light of shorter wavelength (172 nm) in the presence of oxygen is a powerful technique for the functionalization of the terminal groups. 4,8 Several methods were reported for the preparation of alkyl-SAMs on a hydrogenterminated silicon (H-Si) substrate by heat, [9][10][11] ultraviolet (UV) exposure, 6,[12][13][14] visible (Vis) light exposure 6,15 and localized surface plasmons.…”

Functionalization of Oxide‐Free Silicon Surfaces for Biosensing Applications

“…For photo‐initiated hydrosilylation reactions, four mechanisms have been proposed: [ 41 ] i) Si H bond homolysis followed by a radical reaction as described above, [ 51 ] ii) photoemission: photo induced electron emission followed by a nucleophilic attack on the positively charged silicon and hydrogen migration, [ 52 ] iii) plasmon‐mediated, [ 53 ] and iv) exciton‐mediated initiation: [ 45 ] a valence band electron is excited to the conduction band and is stabilized through coulomb interaction with the formed electron hole in the valence band.…”

Plasmonic Stamps Fabricated by Gold Dewetting on PDMS for Catalyzing Hydrosilylation on Silicon Surfaces

“…~20 nm diameter gold nanoparticles functionalized with terminal alkene groups preferentially underwent hydrosilylation and concomitant attachment to a silicon surface when illuminated with light that matched to the absorption maximum of the LSPR of the gold. 14 They proposed a mechanism that invoked a direct transfer of the energy of the photon absorbed by the LSPR to drive the hydrosilylation reaction. The wavelengths of green light centred around 520 nm would normally be of insufficient energy to promote hydrosilylation on a flat silicon surface, 15 pointing to the necessity of the LSPR of the nearby gold nanoparticle.…”