Ab Initio Study of H₂ Associative Desorption on Ad-Dimer Reconstructed Si(001) and Ge(001)-(2×1) Surfaces

Abstract

We investigate the pathways of hydrogen migration and associative desorption of H2 on the Si(001) and Ge(001)-(2×1) reconstructed surfaces with adsorbed ad-dimers, using density functional theory methods. Although the trends obtained with common semilocal exchange–correlation functionals such as the generalized gradient approximation are correct, we show that the use of exact short-range Fock exchange in the calculations (by means of hybrid functionals) strongly affects the magnitude of the desorption barriers, especially for Ge surfaces, leading to a better estimate of the desorption temperatures. Our results for H2 desorption kinetic barriers are well-supported experimentally and can therefore help to elucidate the mechanisms driving atomic layer epitaxy growth processes.

Nanopatterning of Group V Elements for Tailoring the Electronic Properties of Semiconductors by Monolayer Doping

“…In addition, atomic H desorbs from the surface (the nanopatterning only occupies 2/3 of the available surface lattice sites). The kinetic barrier for H desorption is not very high, 2.42 eV (see Figure S2 of the Supporting Information), similar to other Si surface orientations . The difference between the two processes (CH 4 and H desorption) originates from the absence of kinetic barrier for the readsorption of H (CH 4 desorption shows a similar kinetic barrier of ∼2.5 eV but negligible reaction energy).…”

First-Principles Study about the Effect of Coverage on H2 Adsorption and Dissociation over a Rh(100) Surface

“…In addition, Zhang et al investigated the adsorption and dissociation of H 2 on Zr(0001) surface with a five-layers p (2 × 2) slab model corresponding to 1/4 ML coverage. Longo et al studied the pathways of H migration and the desorption of H 2 on Ge(001) surface with a p (2 × 1) unit cells corresponding to 1/2 ML coverage. DFT studies by Xie et al have investigated the surface structure, adsorption sites and adsorption energies of H 2 adsorption on Fe(110) surface, as well as the geometries and stability under different H coverage using different surface supercells.…”

“…As mentioned above, although previous experimental and theoretical studies have investigated the adsorption and dissociation of H 2 over various metal surfaces, these studies mainly focus on the adsorption of H 2 /H at the low coverage conditions, in which only one H 2 /H adsorbed over metal surface has been considered. − ,− ,− Up to now, to the best of our knowledge, the studies about the adsorption and dissociation of H 2 at high coverage over metal surfaces are still scare, moreover, few studies have been performed to probe into the effect of coverage on the adsorption and dissociation of H 2 over metal surface. Recently, theoretical calculations have been used as a powerful tool to clarify the adsorption and activation mechanism of gas molecule on metal catalysts, ,,, as well as the reaction mechanism and kinetics of many typical reactions. ,,,,, Hence, in this study, the adsorption and dissociation of H 2 at different coverage, as well as the effect of coverage on H 2 adsorption and dissociation over the open Rh(100) surface have been systematically investigated using the first-principles density functional theory method.…”

Growth Mechanism of SiC CVD: Surface Etching by H2, H Atoms, and HCl

“…There are several studies in the literature of H2, H atoms and HCl reactions on semiconductor surfaces such as Si [12][13][14][15][16][17] , c-SiC 16,[18][19][20][21] as well as h-SiC [22][23][24] . In most cases, the focus was placed on reconstructed surfaces, both clean and hydrogenated, known to exist in a near vacuum atmosphere.…”

“…There are several studies in the literature of H 2 , H atoms and HCl reactions on semiconductor surfaces such as Si, − c-SiC ,− as well as h-SiC. − In most cases, the focus was placed on reconstructed surfaces, both clean and hydrogenated, known to exist in a near vacuum atmosphere. In this work, we focus instead on the effects of etching during the growth which likely happens in a layer by layer fashion .…”