Effective passivant pseudopotentials for semiconductors: Beyond the spherical approximation

Abstract

An effective atomic pseudopotential for passivation of semiconductor surfaces is presented. It is shown that the spherical approximation used in the effective and empirical pseudopotential methods is not suitable for describing passivants and that, instead, they have to be regarded as complex quantities. Since the new pseudopotentials cannot be handled as usual bulk ones, the way of implementing them in atomistic methods is described here, together with a methodology for extracting them trough an analytic connection to density functional theory, meaning that these surface potential keeps the ab inito identity. The effectiveness and high transferability of the approach is demonstrated by generating passivant potentials for six different semiconductor compounds (GaAs, AlAs, Si, Ge, CdSe and ZnO) and testing them on different kinds of surfaces, including a passivated 68 atoms CdSe quantum wire in wurtzite structure, obtaining always an excellent agreement to density functional theory calculations done on the same systems.

Stability of wurtzite semipolar surfaces: Algorithms and practices

“…One possible way is to use fractionally charged elements [51] with proper atomic sizes, for instance, 1.5e charged lithium used for passivating two nitrogen dangling bonds, or 6.5e charged fluorine used for two gallium dangling bonds. Therefore, proper generated passivant pseudopotentials are necessary [52], while it is out of scope of this paper. If all the PCPs are exact, the residue energy should be zero.…”

“…One possible way is to use fractionally charged elements [51] with proper atomic sizes, for instance, 1.5e charged lithium used for passivating two nitrogen dangling bonds, or 6.5e charged fluorine used for two gallium dangling bonds. Therefore, proper generated passivant pseudopotentials are necessary [52], while it is out of scope of this paper. Additionally, for the self-consistency (or accuracy) estimation, if both the top and bottom surfaces are cut into zigzag structures, and all the dangling bonds are passivated by pseudo-H atoms, we shall define a residue energy as:…”