Density functional study of XH₄ (XSi and Ge) reactivity upon dissociative adsorption onto the Si(100) surface

Abstract

ABSTRACT:Total energy calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and ultrasoft pseudopotential approximation and an analysis tool of atom-resolved density of states (ADOS) have been used to investigate (1) the energetic profiles for the possible initial dissociative adsorption of XH 4 (XASi and Ge) onto the Si(100)O(2 ϫ 2) surface to evaluate their reactivity and (2) the effect of surface electronic states of Si(100)O(2 ϫ 2) on gaseous molecular precursors XH 4 (XASi and Ge) during initial dissociative adsorption to understand the factors governing their reactivity. Our calculated lower-energy barrier for initial dissociative adsorption of GeH 4 is due to the forming of stronger bond of SiOH between H within GeH 4 and buckled-down Si atom on the Si(100)O(2 ϫ 2) surface accompanying the larger extent of unbuckling of the buckled SiASi dimer on the Si(100)O(2 ϫ 2) surface at the transition state. Our evaluated better reactivity for GeH 4 than SiH 4 (a factor of around 14.6) is slightly larger than observed higher reactivity for GeH 4 than SiH 4 (a factor of between 2 and 5 depending on the incident kinetic energy) employed supersonic molecular bean techniques. Finally, our calculated ADOS indicate that the surface electronic states of buckled SiASi dimer on the Si(100)O(2 ϫ 2) surface energetically favorably participate in the transition state during GeH 4 initial dissociative adsorption to reduce the energy barrier, i.e., enhance its reactivity, in comparison with SiH 4 initial dissociative adsorption onto the Si(100)O(2 ϫ 2) surface under the same reaction conditions.

DFT study of surface reactivity of CX3I (XH and F) with CH2I2 to form CH2CX2 on the Ag(111) surface

“…In consequence, this modified PSCPM approach should provide even more realistic reaction profiles and corresponding transition states. The technical details of the PSCPM method is described in our previous paper [16,23,24]. Other reaction routes are not considered, either because the CX 3(ads) will proceed over very stable sites, namely, top sites, or the CX 3(ads) will go over a much larger distance.…”

Density Functional Study of the Interfacial Electron Transfer Pathway for Monolayer-Adsorbed InN on the TiO2 Anatase (101) Surface

“…In this study, we consider Ti, O, In, and N as the constituent atoms to generate the PDOS, and their space cuts are chosen as their covalent radii, respectively. Technical details about our total energy calculation method, the ultrasoft pseudopotential generation scheme, and the PDOS calculation scheme have been reported elsewhere . We performed all the total energy and PDOS calculations using a modified version of CASTEP 3.9 …”

“…A few years ago we performed total energy calculations based on density functional theory to study the structural and electronic properties of adsorbed silane on both Si(100) and Ge(100) surfaces. , To realize the different electronic states from these two surfaces and their effects on the SiH 4 adsorption reaction mechanisms, we also calculated the PDOS for the surface layer of both surfaces. Indeed, these calculated PDOS showed that the higher electronic states from both surfaces play an important role in governing the reactivity for the SiH 4 adsorption reaction on these two surfaces.…”

Особенности Взаимодействия Молекул Германа С Поверхностью Германия В Вакууме И В Присутствие Потока Водорода

“…Более простым способом оценки коэффициента захвата молекул газа ростовой поверхностью, традиционно применяемым в литературе, является использование выражений, получаемых на базе простейшей системы кинетических уравнений. При этом в подавляющем большинстве случаев ограничиваются балансом между адсорбционной по гидриду и десорбционной по водороду составляющими [5,30,32,33]. Предполагается, что первый механизм отвечает за рост пленки при высокой температуре.…”