Surface Electronic Excited State on Si(100):  Structure, Energetics, Lifetime, and Role in Chemical Reactions

Abstract

The lowest electronic excited state on the Si(100) surface and its coupling to the ground electronic state have been investigated using first-principles theory. The energy difference between the optimal geometry in the two states is small enough for a significant equilibrium population of the excited state to exist under common reaction conditions. The kinetics of crossing between spin states have been determined by explicit calculation of the minimum-energy crossing point and the spin−orbit coupling between them. The predicted excited-state lifetime is very short, except at low temperature.

Packing structure of MPS SAMs and its influence on oriented deposition of SnO2 crystal films

“…The Si (100) surface is the most important reconstructed surface 39, 40. In all kinds of Si (100) reconstruction surfaces, the 2 × 1 reconstruction is the most stable structure 41–43. In our simulation, we created the Si (100) 2 × 1 reconstructed surface including four layers of silicon atoms as the substrate.…”

Relativistic potential energy surfaces of initial oxidations of Si(100) by atomic oxygen: The importance of surface dimer triplet state

“…21 However, the exact roles of singlet as well as triplet atomic oxygens in the initial adsorptions have not been well understood. On the other hand, experimental 22 as well as theoretical 17,23,24 studies of the excitation energy of the Si(100) surface itself have been carried out. Optical measurements indicate an indirect band gap of 0.44-0.64eV for the Si(100) surface.…”

Molecular Modeling of Alkyl Monolayers on the Si(100)−2 × 1 Surface

“…As a result of silicon's central role in modern semiconducting manufacturing and micromachining, there has recently been significant interest in functionalizing its surface with organic monolayers. − The silicon surface may appear as a reconstruction, for example, Si(100)−2 × 1 or Si(111)−7 × 7, − as planar [Si(111)−H or Si(100)−H 2 ] − or porous hydrogen-terminated silicon − or as ground , or scribed silicon. − Some of the most important chemistry for all of these surfaces is their reaction with carbon−carbon double or triple bonds. In particular, 1-alkenes and 1-alkynes undergo a [2 + 2] addition onto the silicon−silicon dimer of Si(100)−2 × 1 to form four-membered rings that contain two carbon−silicon single bonds in a “di-σ” configuration.…”

“…This di-σ configuration is the most likely mode of binding and is used in this work . Other bonding configurations for acetylene, including “end-bridge” and “tetra-σ”, have also been proposed. − Ethylene and acetylene react with the Si(100) reconstructed surface up to 100% coverage, but after 50% coverage high dosages are required to functionalize the remaining surface. ,− …”

“…Here we present a molecular modeling study of monolayers of 1-alkenes and 1-alkynes on Si(100)−2 × 1, which is silicon's most studied and important reconstruction. , While a number of ab initio calculations of the reaction of one or even a few reactive molecules with Si(100)−2 × 1 have been performed, ,,, we are not aware of any molecular modeling study of alkyl monolayers on reconstructed Si(100). Here we find that molecular modeling studies support the 100% coverages found experimentally for ethylene (see Figure ) and acetylene and may provide some insight into the reasons for the reduced sticking coefficient after 50% coverage.…”