Density functional study of gas–surface reactivity: GeH4 dissociative adsorption onto semiconductor surfaces

Lin, Jim‐Min; Chou, Wen-Chi

doi:10.1016/s0166-1280(03)00406-8

Cited by 7 publications

(3 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this paper, we therefore present our thorough DFT [15] study to reexamine the overall reaction profiles for CH 2(ads) and CX 3(ads) (XAH and F) on the Ag(111) surface to form an isolated CH 2 ACX 2(g) through the CH 2 insertion into AgOCX 3 bond followed by ␤OX elimination. Particularly, we apply the partial structure constraint path minimization (PSCPM) method [16,17] with chemical intuition to determine the possible transition-state structures and the corresponding energy barriers along the energetically more favorable paths. We are hoping that all these calculated results will allow us to compare the relative rates of both CH 2 insertion into AgOCX 3 bond and ␤OX elimination to form an isolated CH 2 ACX 2(g) on the Ag(111) surface and to give a microscopic insight into factors governing the formation rate of an isolated CH 2 ACX 2(g) for complementing the experimental data.…”

Section: Introductionmentioning

confidence: 99%

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

Lin¹,

Chou²

2005

Int J of Quantum Chemistry

Self Cite

View full text Add to dashboard Cite

ABSTRACT:Recently, Chiang's research group successfully carried out the temperature programmed reaction (TPR) spectroscopy under ultrahigh-vacuum conditions to probe the reaction pathways of adsorbed methyl (CH 3(ads) ) and trifluoromethyl (CF 3(ads) ) with coadsorbed methylene (CH 2(ads) ) via the CH 2 insertion reaction, leading to the formation of adsorbed 1,1,1-trifluoro-ethyl (CF 3 CH 2(ads) ) and ethyl (CH 3 CH 2(ads) ) on the Ag(111) surface. Additionally, the authors found it feasible for CF 3 CH 2(ads) to proceed the subsequent ␤-fluoride elimination on the Ag(111) surface to produce 1,1 difluoroethylene (CF 2 ACH 2(g) ) but difficult for CH 3 CH 2(ads) to proceed ␤-hydride elimination to form ethylene (CH 2 ACH 2(g) ) on the Ag(111) surface. To elaborate on this noticeably different reactivity between ␤-hydride and ␤-fluoride eliminations on the Ag(111) surface we performed total energy calculations based on density functional theory in connection with ultrasoft pseudopotential and generalized gradient spin-polarized approximation, and partial structural constraint path minimization to establish the energetically more favorable pathways for the CH 2 insertion into AgOCX 3 (XAH and F) bonds followed by ␤-X elimination to generate an isolated CH 2 ACX 2(g) on the Ag(111) surface. Following our proposed reaction pathways, namely, the diffusion of the fcc-hollow site of CX 3(ads) toward the bridge site of CH 2(ads) through the CH 2 insertion and the subsequent ␤-X elimination to form both isolated CH 2 ACX 2(g) and hcp-hollow site of X (ads) on the Ag(111) surface, our calculated energy barrier for ␤-hydride elimination is significantly larger than (ϳ0.661 eV) that for ␤-fluoride elimination. This unusual high-energy barrier prohibits ␤-hydride elimination of CH 2 CH 3(ads) to form an isolated CH 2 ACH 2(g) on the Ag (111) surface and explains what we observed from the TPR experimental data. We also attribute this much higher energy barrier to forming a largely distorted seven-center ring transition state structure with a larger distortion of the AgOC (␣) H 2 C (␤) H 3 OAg and a less stable AgOH bond on the Ag(111) surface. Finally, our calculated energy barrier for ␤-fluoride elimination to form CH 2 ACF 2(g) is 0.687 eV, in very good agreement with the experimental data.

show abstract

Section: Introductionmentioning

confidence: 99%

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

Lin¹,

Chou²

2005

Int J of Quantum Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…With our GS-MBE method, the Si substrate was exposed to GeH 4 without gas-phase thermal cracking and it has been reported that GeH 4 is thermally decomposed on the Si(001) surface and initial Ge adsorbates are hydrides such as GeH 3 and GeH 2 . [25][26][27] However, adsorbates formed with the sputter epitaxy method are basically nonhydrogenated Ge. In analogy with the fact that the binding energies between silicon hydrides and Si(001) are smaller than those between bare Si and Si(001), [28][29][30] bare Ge is expected to be less movable on a Si surface than Ge hydrides, and we have also reported that the experimentally measured Ge migration length on Si(001) with the sputter epitaxy method is shorter than that with the GS-MBE method.…”

Section: Flattening Mechanism Of Ge Layer On Heavily P-dopedmentioning

confidence: 99%

Ge Flat Layer Growth on Heavily Phosphorus-Doped Si(001) by Sputter Epitaxy

Hanafusa

Hirose

Kasamatsu

et al. 2012

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

We have investigated layer-by-layer Ge growth methods on phosphorus (P)-doped Si(001) with our sputter epitaxy method at a growth temperature (T G) of 350 °C. With the sputter epitaxy method, relaxed Ge islands are formed on P-doped 3.5 Ω cm Si with Ge–Si intermixing at the Ge/Si interface; however, a partially strained flat Ge layer is grown directly on P-doped 0.015 Ω cm Si. For comparison with a gas-source molecular beam epitaxy (GS-MBE) method using GeH4, Ge islands are formed on 0.015 Ω cm Si at T G = 350 °C. It has been suggested that the P dopants together with the sputter epitaxy method effectively suppress Ge islanding and induce Ge layer-by-layer growth.

show abstract

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Lin

Chou

et al. 2006

J. Phys. Chem. B

Self Cite

View full text Add to dashboard Cite

Density functional theory (DFT) in connection with ultrasoft pseudopotential (USP) and generalized gradient spin-polarized approximations (GGSA) is applied to calculate the adsorption energies and structures of monolayer-adsorbed InN on the TiO(2) anatase (101) surface and the corresponding electronic properties, that is, partial density of states (PDOS) for surface and bulk layers of the TiO(2) anatase (101) surface and monolayer-adsorbed InN, to shed light on the possible structural modes for initial photoexcitation within the UV/vis adsorption region followed by fast electron injection through the InN/TiO(2) interface for an InN/TiO(2)-based solar cell design. Our calculated adsorption energies found that the two most probable stable structural modes of monolayer-adsorbed InN on the TiO(2) anatase (101) surface are (1) an end-on structure with an adsorption energy of 2.52 eV through N binding to surface 2-fold coordinated O (O(cn2)), that is, InN-O(cn2), and (2) a side-on structure with an adsorption energy of 3.05 eV through both N binding to surface 5-fold coordinated Ti (Ti(cn5)) and In bridging two surface O(cn2), that is, (O(cn2))(2)-InN-Ti(cn5). Our calculated band gaps for both InN-O(cn2) and (O(cn2))2-InN-Ti(cn5) (including a 1.0-eV correction using a scissor operator) of monolayer-adsorbed InN on the TiO(2) anatase (101) surface are red-shifted to 1.7 eV (730 nm) and 2.3 eV (540 nm), respectively, which are within the UV/vis adsorption region similar to Gratzel's black dye solar cell. Our analyses of calculated PDOS for both surface and bulk layers of the TiO(2) anatase (101) surface and monolayer-adsorbed InN on the TiO(2) anatase (101) surface suggest that the (O(cn2))(2)-InN-Ti(n5) configuration of monolayer-adsorbed InN on the TiO(2) anatase (101) surface would provide a more feasible structural mode for the electron injection through the InN/TiO(2) interface. This is due to the presence of both occupied and unoccupied electronic states for monolayer-adsorbed InN within the band gap TiO(2) anatase (101) surface, which will allow the photoexcitation within the UV/vis adsorption region to take place effectively, and subsequently the photoexcited electronic states will overlap with the unoccupied electronic states around the lowest conduction band of the TiO(2) anatase (101) surface, which will ensure the electron injection through the InN/TiO(2) interface. Finally, another thing worth our attention is our preliminary study of double-layer-adsorbed InN on the TiO(2) anatase (101) surface, that is, (O(cn2))(2)-(InN)(2)-Ti(cn5), with a calculated band gap red-shifted to 2.6 eV (477 nm) and a different overlap of electronic states between double-layer-adsorbed InN and the TiO(2) anatase (101) surface qualitatively indicated that there is an effect of the thickness of adsorbed InN on the TiO(2) anatase (101) surface on both photoexcitation and electron injection processes involved in the photoinduced interfacial electron transfer through InN/TiO(2). A more thorough and comprehensive study of different la...

show abstract

Density functional study of gas–surface reactivity: GeH4 dissociative adsorption onto semiconductor surfaces

Cited by 7 publications

References 24 publications

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

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

Ge Flat Layer Growth on Heavily Phosphorus-Doped Si(001) by Sputter Epitaxy

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

Contact Info

Product

Resources

About

Density functional study of gas–surface reactivity: GeH4 dissociative adsorption onto semiconductor surfaces

Cited by 7 publications

References 24 publications

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

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

Ge Flat Layer Growth on Heavily Phosphorus-Doped Si(001) by Sputter Epitaxy

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

Contact Info

Product

Resources

About

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

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

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