Simulation of bulk silicon crystals and Si(111) surfaces with application to a study of fluorine coverage of the surfaces

Abstract

Computational efficiency for the simulation of bulk crystals and surfaces is highly desirable. In an effort to study semiconductor crystals, we present a self-consistent treatment for the simulation of silicon crystals and surfaces based on the combination of a siligen model and a semiempirical Hamiltonian method. An artificial atom called siligen is introduced for the application of the semiempirical method to finite-size silicon clusters. The calculated average bond energies for the saturated silicon clusters are between 2.045 and 2.568 eV, compared to the measured value of 2.31 eV. A simulated bulk silicon surface using siligens is introduced in order to examine variation of the bond strength between fluorine atoms and the simulated silicon (111)surface. It is found that bond strength computed from the simulated surface, with siligens, rapidly converges to a saturated limit as the number of surface layers increases, while a pure silicon (111)surface without siligens yields no satisfactory convergence.

A Quantum Chemistry Approach to Possible Sulfur Adsorbate Structures on the Basal Plane of Graphite Clusters

“…The semiempirical molecular orbital method MNDO has been extensively tested and applied to a wide number of molecules, radicals, and triplet states of different type, yielding geometries (bond lengths and angles), ionization potentials, dipole moments, polarizabilities, heats of formation, and reaction mechanisms with accuracy. The original description of the MNDO method has been given by Dewar and Thiel. 11a-c Parameters for atoms employed in our calculations were taken from those published by Dewar and Thiel and Dewar et al 11a-c The selection of this method was based on its efficiency when only s and p orbitals are involved, as is the case dealt with in this work. In addition, the success of the method in modeling surfaces within the cluster approach has been demonstrated, for example, in the case of Si surfaces both unreconstructed and reconstructed, 11d-g where its performance resulted comparable to ab initio and other semiempirical methods, in the reconstruction of C(100) (diamond surface),11g and C(111) surface 11h which reconstructs due to a graphite-like bonding between the first two surface layers.…”

“…The original description of the MNDO method has been given by Dewar and Thiel. 11a-c Parameters for atoms employed in our calculations were taken from those published by Dewar and Thiel and Dewar et al 11a-c The selection of this method was based on its efficiency when only s and p orbitals are involved, as is the case dealt with in this work. In addition, the success of the method in modeling surfaces within the cluster approach has been demonstrated, for example, in the case of Si surfaces both unreconstructed and reconstructed, 11d-g where its performance resulted comparable to ab initio and other semiempirical methods, in the reconstruction of C(100) (diamond surface),11g and C(111) surface 11h which reconstructs due to a graphite-like bonding between the first two surface layers. Moreover, the MNDO method has been recently used to study the X-ray structure of coronene−potassium as a model for potassium (adsorbate) graphite surface interactions 11i…”

Three-temperature modeling of laser-induced damage process in silicon

“…The TDDFT results suggests the bond-breaking energy is a reasonable candidate for the damage threshold. Threshold for breaking of bonds is calculated as the threshold fluence when energy per atom reaches 2.3 eV, which is half the cohesive energy of a silicon crystal [33].…”

Effects of electrically active impurities on the bond energy in silicon:Ab initiototal energy cluster study

“…17 as hydrogen with the nonhydrogen Slater exponent S of the 1s orbital (e Ϫ S r). Lutrus et al 14 used siligen to simulate bulk silicon and have found the silicon binding energy close to experimental data. The quasihydrogen approach has been used by the author and co-workers 18,19 for investigation of the electronic structure of some silicon and metal-silicon systems, and now the same approach is applied to study the influence of active impurities on the binding energy of silicon.…”

“…10 Finite-size clusters have often been used to simulate bulk crystals. [11][12][13][14] Broken bonds of silicon usually are saturated by hydrogen atoms 15,16 or atoms of quasihydrogen ͑so-called siligen͒. 17 Siligen was defined in Ref.…”