Chemical Trends in the Work Function of Modified Si(111) Surfaces: A DFT Study

Abstract

Using first-principles, we provide predictions for chemical trends in the work function of silicon (111) surfaces modified with various terminations. For nonpolar terminating atomic species such as F, Cl, Br, and I, the change in the work function is directly proportional to the amount of charge transferred from the surface, thus relating to the difference in electronegativity of the adsorbate and silicon atoms. The change is a monotonic function of coverage in this case, and the work function increases with increasing electronegativity. Polar species such as −TeH, −SeH, −SH, −OH, −NH 2 , −CH 3 , and −BH 2 do not follow this trend due to the interaction of their dipole with the induced electric field at the surface. In this case, the magnitude and sign of the surface dipole moment need to be considered in addition to the bond dipole to generally describe the change in work function. Compared to hydrogenated surfaces, there is slight increase in the work function of H:Si(111)-XH, where X = Te, Se, and S, whereas reduction is observed for surfaces covered with −OH, −CH 3 , and −NH 2 . Our analysis contributes to a microscopic understanding of induced changes in experimentally studied silicon surfaces.

Facet‐Dependent Electrical Conductivity Properties of Silver Oxide Crystals

“…First-principles geometry optimization was performed based on density function theory (DFT) with the Perdew-Burke-Ernzerhof generalized gradient approximation (GGA). [25][26][27] First-principles DFT-GGA calculations were carried out by using the plane wave ultrasoft pseudopotential method, as implemented in the Cambridge Serial To tal Energy Package (CASTEP). The plane-wave basis set cutoff energy is 380 eV.W eused af ine k-point mesh of 5 5 4f or the Brillouin zone.…”

Binary functionalization of H:Si(111) surfaces by alkyl monolayers with different linker atoms enhances monolayer stability and packing

“…7,43 We perform periodic supercell calculations using a plane wave basis set within the PWSCF code of the QUANTUM-ESPRESSO distribution, 50 with the PBE gradient corrected functional. 51 The electron-ion interaction is described by ultrasoft pseudopotentials (USPPs) with the following number of valence electrons for each element: surface were created to give supercells that allow us to simulate target coverages.…”

“…We calculate the total, radical and effective dipole moments 42,43 of all modified H:Si(111) systems and these data are presented in Table 2. We focus initially on the simpler case of -XH terminations only.…”

Expanding the Repertoire of Molecular Linkages to Silicon: Si–S, Si–Se, and Si–Te Bonds

“…23 Bonding of SAMs through Si−O, Si−S, Si−Se, Si−Te, and Si− N bonds as well as SiX (X = halide) coverage were examined; for heavier atoms (Te versus Se versus S versus O), additional electronic states are available, which can affect electron transfer to and from molecules attached to a silicon surface. 21,24 In contrast to the vast literature of SAMs bonded to silicon through Si−C 25,26 and Si−O linkages, 27,28 the development of silicon−chalcogenide bond-forming reaction schemes on silicon surfaces has only just begun, in spite of the strong impetus to study, understand, and apply them. The field of Si− S-and Si−Se-based SAMs on surfaces via solution (nonvacuum) chemistry can be summarized in one paragraph.…”