Raman Spectroscopy on Surface Phonons of Si(hhk) Surfaces Modified by Au Submonolayers

Abstract

Raman spectroscopy has evolved to a sensitive tool for analyzing vibration modes of ordered (sub)monolayers of metal adatoms on semiconductor surfaces, which are typical systems for electron correlation effects. We report on the in situ UHV Raman analysis of self-organized Au submonolayers on nominal Si(111) surfaces, as well as on vicinal Si(553), Si(775), and Si (557). For the two-dimensional Au-ð ffiffi ffi 3 p  ffiffi ffi 3 p Þ and the one-dimensional Au-(5  2) reconstruction several specific Raman peaks in the spectral range below 200 cm À1 are assigned to Au-dominated vibration modes, while Si-step-edge vibration modes around 400 cm À1 are fingerprints of the substrate orientation.

Spectroscopic Analysis of Rare-Earth Silicide Structures on the Si(111) Surface

“…The signatures at 104.3 , 121.0 , 156.8 , 198.8 , and 346.4 , are close to critical points of the phonon dispersion and might be either surface activated resonances or the overlap of surface localized modes and bulk resonances. Surface-activated bulk resonances were already reported for Au superstructures on different vicinal Si(111) substrates at very similar frequencies and were attributed to the altered boundary conditions by the metallic superstructures [ 52 ]. Most probably, the signature measured at 449.1 is related to the optical phonon, which becomes very flat at the point of the Brillouin zone, resulting in a very high phonon DOS just above 450 .…”

“…The Raman modes observed in the surface spectrum overlap, at least partially, with the bulk phonon branches of Si. As shown previously on different Si( )-Au systems, surfaces resonances may arise by coupling to bulk phonon modes close to the Brillouin zone boundaries, activated by the surface modification [ 52 ]. Therefore, part of the observed modes will have predominant bulk character, while others will be mostly surface localized.…”

Adsorption of toluene‐3,4‐dithiol on silver islands investigated by surface‐enhanced Raman spectroscopy

“…Substrate contributions to the SERS signal were eliminated by extraction of the difference between the spectra of the SERS substrate before and after deposition of TDT. This methodology has been applied in Raman studies of other adsorbates on Si substrates …”

“…This methodology has been applied in Raman studies of other adsorbates on Si substrates. [24][25][26]…”

Surface‐enhanced Raman spectroscopy for on‐site analysis: A review of recent developments

“…Compared with the front-illuminated open-electrode CCD, the quantum efficiency of the Si-based CCD has been greatly improved, and reached 95%. [77][78][79] Mooreet al made a detailed review of commercial Raman spectrometers. [62] In recent years, increasing numbers of portable Raman instrument manufacturers (InPhotonics, Ocean Optics, Thermo Fisher Scientific, Horiba, Zolix, Mettler Toledo, Anton Paar, B&W Tek, Smiths Detection) have emerged and devices with the advantages of miniaturization, handheld or lightweight applications and high resolution are available (partial technical information is shown in Table 1).…”