Valence band effective-mass expressions in thesp3d5s*empirical tight-bin

Abstract

Exact, analytic expressions for the valence band effective masses in the spin-orbit, sp 3 d 5 s* empirical tight-binding model are derived. These expressions together with an automated fitting algorithm are used to produce improved parameter sets for Si and Ge at room temperature. Detailed examinations of the analytic effective-mass expressions reveal critical capabilities and limitations of this model in reproducing simultaneously certain gaps and effective masses. The ͓110͔ masses are shown to be completely determined by the ͓100͔ and ͓111͔ masses despite the introduction of d orbitals into the basis.

Bandstructure and mobility variations in p-type silicon nanowires under electrostatic gate field

“…To obtain the bandstructure of the NWs we use the nearest neighbor sp 3 d 5 s * tightbinding model [11,26,27,28,29], which captures all the necessary band features, and in addition, is robust enough to computationally handle larger NW cross sections as compared to ab-initio methods. As an indication, the unit cells of the NWs considered in this study contain up to ~5500 atoms.…”

“…The model itself and the parameterization used [26] The complete computational model is described in Fig. 1 [34].…”

Hierarchical simulation of transport in silicon nanowire transistors

“…We have performed our simulations both including or neglecting the effect of spin-orbit coupling; we have therefore considered 20 atomic orbitals or 10 atomic orbitals, respectively, for each of the silicon atoms belonging to the nanowire unit cell (which for our transport direction includes 4 atomic layers). Using as a basis set the Bloch functions propagating along the nanowire axis and obtained from the atomic orbitals considered in the nanowire unit cell, we have computed the Hamiltonian matrix H (k) for each considered longitudinal wave vector k. In particular, the matrix elements between nearest-neighbor atomic orbitals have been obtained from the relations found by Slater and Koster [9] and by Podolskiy and Vogl [10], as well as the values proposed for the tight-binding parameters of bulk silicon by Boykin et al [11].…”

Performance Analysis of a Ge/Si Core/Shell Nanowire Field-Effect Transistor

“…nanowire, we assume an unrelaxed nanowire atomic geometry with bulk atomic positions and construct the Hamiltonian of the nanowire unit cell using the orthogonal-basis sp 3 d 5 s* tight-binding method developed for bulk electronic structure 11 . Each atom is modeled using 10 orbitals per atom per spin (20 orbitals per atom total).…”