Crystal facet dependence of SiHCl3 reduction to Si mechanism on silicon rod

Adsorption Behaviors of Chlorosilanes, HCl, and H2 on the Si(100) Surface: A First-Principles Study

“…Moreover, the SiCl 4 adsorption leads to the formation of SiCl 2 (Figure a), which indicates that the SiCl 2 molecule is spontaneously formed during SiCl 4 adsorption. Specifically, the minimum energy path (MEP) to search for the involved transition state in SiCl 2 formation was obtained by LST/QST tools , in DMol 3 code 8.0. The barrier energy E a reported herein was calculated as follows E normala = E TS − E IS where E IS and E TS represent the total energy of the initial state (IS) and transition state (TS), respectively.…”

“…Therefore, the transition of SiHCl 2 to SiCl 2 should overcome a certain energy barrier. As shown in Figure , the reaction of SiHCl 2 to SiCl 2 on Si(100) is exothermic with an energy of 44.38 kJ/mol, and the calculated reaction barrier is about 110.00 kJ/mol, which is smaller than that of SiHCl 2 dissociating into SiCl 2 on the Si(111) surface (147.90 kJ/mol) . In conclusion, SiCl 4 can be directly dissociated into SiCl 2 on the Si(100) surface.…”

“…We chose the 4.6 Å cutoff radius for geometry optimization, where a smearing value of 0.005 Ha was employed for rapid convergence. Effective core potential (ECP) of the Hartree–Fock potential is used to treat inner electrons . When the force of relaxed atoms is lower than 5 × 10 –5 Ha, SCF tolerance is lower than 5 × 10 –6 Ha, the force change between two steps is smaller than 0.02 Ha/Å, and the atomic structures tend to be stable.…”

“…Effective core potential (ECP) of the Hartree–Fock potential is used to treat inner electrons. 34 When the force of relaxed atoms is lower than 5 × 10 –5 Ha, SCF tolerance is lower than 5 × 10 –6 Ha, the force change between two steps is smaller than 0.02 Ha/Å, and the atomic structures tend to be stable. To avoid the interaction of each layer during the calculations, a vacuum layer thickness of 15 Å was added to the top of the Si(100) surface.…”

“…As shown in Figure 13, the reaction of SiHCl 2 to SiCl 2 on Si(100) is exothermic with an energy of 44.38 kJ/mol, and the calculated reaction barrier is about 110.00 kJ/mol, which is smaller than that of SiHCl 2 dissociating into SiCl 2 on the Si(111) surface (147.90 kJ/mol). 34 In conclusion, SiCl 4 can be directly dissociated into SiCl 2 on the Si(100) surface. By contrast, SiH 2 Cl 2 and SiHCl 3 molecules first dissociate into SiHCl 2 * without zero energy barrier, and then, the SiHCl 2 molecule converted into SiCl 2 needs to overcome an energy barrier of 110.00 kJ/mol.…”