Surface structure of GaP(110): Ion scattering and density functional theory study

Abstract

The structure of the GaP(110) surface has been investigated using coaxial impact collision ion scattering spectroscopy (CAICISS) and density functional theory (DFT). CAICISS simulations based on structural parameter values of the well known buckled dimer model obtained in quantitative low energy electron diffraction studies in the 1980s were found to fit well with experimental data measured in the [110] azimuth, but offered a relatively poor fit in all other incident geometries. A new surface structure derived from DFT calculations, involving small changes to bond angles and interlayer spacings, was optimized during the analysis of CAICISS data, until good fits of the data were obtained for all three azimuths ([110], [001], and [111]). The key feature of the new structure found to be required for this improved agreement with experiment is the inclusion of relaxations both parallel and perpendicular to the surface between the second and third layers.

Adsorption and Stability of π-Bonded Ethylene on GaP(110)

“…To better understand our experimental observations for ethylene/GaP(110), we investigated this adsorption system using DFT calculations and directly compared them to our measurements. Our DFT-PBE structural optimization of the GaP(110) surface (Figure c) yielded a surface buckling of 0.63 Å relative to the truncated bulk structure and a unit cell of 5.50 Å along [001] and 3.89 Å along the [11̅0] direction, in good agreement with previous calculations . Simulated images of the surface at different experimental biases (see Supporting Information for details) are shown in Figure a and accurately reproduce all of the features observed in the STM images at both bias polarities.…”

“…Our DFT-PBE structural optimization of the GaP(110) surface (Figure 2c) yielded a surface buckling of 0.63 Å relative to the truncated bulk structure and a unit cell of 5.50 Å along [001] and 3.89 Å along the [11̅ 0] direction, in good agreement with previous calculations. 27 Simulated images of the surface at different experimental biases (see Supporting Information for details) are shown in Figure 2a and accurately reproduce all of the features observed in the STM images at both bias polarities. The band structure obtained using an additional GW-based correction (see Supporting Information) is shown in Figure 2d.…”

Low temperature removal of surface oxides and hydrocarbons from Ge(100) using atomic hydrogen

“…Atomic hydrogen cleaning (AHC) has been shown to offer an effective route to the removal of surface hydrocarbons and oxides in a range of semiconductor materials, including GaP [27], GaMnAs [28], GaAs [29], GaSb [30], InAs [31,32], InN [33], and InP [34]. The AHC process removes surface oxides and hydrocarbons via chemical reaction on the surface, followed by desorption in to the vacuum, and ordered surfaces can typically be achieved at lower temperatures.…”