Surface phonon dispersion on hydrogen-terminated Si(110)-(1 × 1) surfaces studied by first-principles calculations

Abstract

We studied the lattice constants, surface-phonon dispersion curves, spectral densities, and displacement vectors of the hydrogen-terminated Si(110)-(1 × 1) [H:Si(110)-(1 × 1)] surface using the first-principles calculations within the framework of density functional theory (DFT). The symmetry of the H:Si(110)-(1 × 1) surface belongs to the two-dimensional space group p2mg, which has two highly symmetric and orthogonal directions, ΓX¯ and ΓX(')¯, with the glide planes along the ΓX¯ direction. Because glide symmetry separates the even and odd surface phonon modes, we mapped the even surface modes in the first surface Brillouin zone (SBZ) and the odd surface modes in the second SBZ using the spectral densities and displacement vectors. The surface phonon modes were analyzed with respect to their physical origin, spatial localization properties, polarization, and the charge density of their electronic states. Our calculated surface phonon modes were in good agreement with recent high-resolution electron-energy-loss spectroscopy data in the first and second SBZs of the ΓX¯ direction. In the SBZ of the ΓX(')¯ direction, our calculated surface phonon modes agree well with the data in the energy region below 65 meV but are not satisfactorily compatible with those in the stretching and bending modes. In addition, we discuss the microscopic nature of the surface phonon dispersion of the H:Si(110)-(1 × 1) surface using the phonon eigen modes.

Wet chemical preparation and isotope exchange process of H/D-terminated Si(111) and Si(110) studied by adsorbate vibrational analysis

“…[7][8][9] At θ D = 0.76, the peak position decreases to 257.3 meV, which is almost exactly the energy of the antisymmetric stretching mode of 257.2 meV. 8,9) The present data set for the D-Si stretching energy does not involve distinctive changes, and is scattered at approximately 187.7 meV within the peak readout error. It is clear that a certain interaction induces a red shift of the H-Si stretching frequency on Si(110).…”

“…Detailed descriptions of the apparatus and contamination-free sample transfer procedures are given in our previous reports. [7][8][9]27) The scanning tunneling microscope (STM; Specs STM 150 Aarhus) was used for the STM measurements in a separate chamber. 7) 3.…”

“…Results and discussion 3.1 Model geometry of hydrogen-terminated Si(111) and Si(110) Before proceeding to the vibrational and geometrical analyses, we review the surface atomic arrangement on hydrogenterminated Si(111) and Si(110) surfaces based on knowledge accumulated so far. [7][8][9][18][19][20][22][23][24][25][26][27] Figure 1 shows model structures of hydrogen-terminated Si(111) and Si(110). The H:Si(111) surface inherits its periodicity, three fold rotational symmetry (two-dimensional space group p6mm), and unit-cell size from the (111) bulk-truncated plane of the diamond-type Si crystal.…”

“…This energy is regarded to correspond to the symmetric stretching mode of H-Si at 259.1 meV. [7][8][9] At θ D = 0.76, the peak position decreases to 257.3 meV, which is almost exactly the energy of the antisymmetric stretching mode of 257.2 meV. 8,9) The present data set for the D-Si stretching energy does not involve distinctive changes, and is scattered at approximately 187.7 meV within the peak readout error.…”

“…6) Matsushita et al have recently improved the method of preparing hydrogen-terminated Si(110)-(1×1) [H:Si(110)] surfaces 7) and observed one-dimensional phonons along zigzag Si chains on H:Si(110). 8) It was also found that the experimental data for surface phonons on H:Si(110) are useful for estimating the accuracy of first-principles calculations, such as quantum-mechanical calculations based on density functional theory (DFT), particularly in the frameworks of the local density approximation (LDA) 9) and generalized gradient approximation (GGA). 10) There are some inconsistencies between the results of the experiments and calculations, particularly in the vibrational frequencies of surface H atom modes.…”