Vibrational dynamics and band structure of methyl-terminated Ge(111)

Zachary M. Hund, Kevin J. Nihill, Davide Campi, Keith T. Wong, Nathan S Lewis, M. Bernasconi, G. Benedek, S. J. Sibener

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD3-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH3-Ge(111) and CH3-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers.

Original languageEnglish
Article number124705
JournalJournal of Chemical Physics
Volume143
Issue number12
DOIs
Publication statusPublished - Sep 28 2015

Fingerprint

Band structure
Rayleigh waves
Helium
perturbation theory
Semiconductor materials
Semiconducting organic compounds
Lattice vibrations
libration
organic semiconductors
helium atoms
Brillouin zones
vibration mode
Thermodynamic properties
thermodynamic properties
Diffraction
attenuation
helium
Scattering
deviation
Atoms

ASJC Scopus subject areas

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

Cite this

Hund, Z. M., Nihill, K. J., Campi, D., Wong, K. T., Lewis, N. S., Bernasconi, M., ... Sibener, S. J. (2015). Vibrational dynamics and band structure of methyl-terminated Ge(111). Journal of Chemical Physics, 143(12), [124705]. https://doi.org/10.1063/1.4931178

Vibrational dynamics and band structure of methyl-terminated Ge(111). / Hund, Zachary M.; Nihill, Kevin J.; Campi, Davide; Wong, Keith T.; Lewis, Nathan S; Bernasconi, M.; Benedek, G.; Sibener, S. J.

In: Journal of Chemical Physics, Vol. 143, No. 12, 124705, 28.09.2015.

Research output: Contribution to journalArticle

Hund, ZM, Nihill, KJ, Campi, D, Wong, KT, Lewis, NS, Bernasconi, M, Benedek, G & Sibener, SJ 2015, 'Vibrational dynamics and band structure of methyl-terminated Ge(111)', Journal of Chemical Physics, vol. 143, no. 12, 124705. https://doi.org/10.1063/1.4931178
Hund, Zachary M. ; Nihill, Kevin J. ; Campi, Davide ; Wong, Keith T. ; Lewis, Nathan S ; Bernasconi, M. ; Benedek, G. ; Sibener, S. J. / Vibrational dynamics and band structure of methyl-terminated Ge(111). In: Journal of Chemical Physics. 2015 ; Vol. 143, No. 12.
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