arXiv subjects

J. R. Cárdenas

Publications and source records attributed to J. R. Cárdenas.

2 recordsLinked to original sources

arXiv2016

Effective Passivant Pseudopotentials for semiconductors: beyond the spherical approximation

A new type of 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 seudopotentials 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 the new type of surface potential keeps the {\it ab inito} identity. The effectiveness and high transferability of this new 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.

cond-mat.mes-hall↗

arXiv2012

Atomic Effective Pseudopotentials for Semiconductors

We derive an analytic connection between the screened self-consistent effective potential from density functional theory (DFT) and atomic effective pseudopotentials (AEPs). The motivation to derive AEPs is to address structures with thousands to hundred thousand atoms, as given in most nanostructures. The use of AEPs allows to bypass a self-consistent procedure and to address eigenstates around a certain region of the spectrum (e.g., around the band gap). The bulk AEP construction requires two simple DFT calculations of slightly deformed elongated cells. The ensuing AEPs are given on a fine reciprocal space grid, including the small reciprocal vector components, are free of parameters, and involve no fitting procedure. We further show how to connect the AEPs of different bulk materials, which is necessary to obtain accurate band offsets. We derive a total of 20 AEPs for III-V, II-VI and group IV semiconductors and demonstrate their accuracy and transferability by comparison to DFT calculations of strained bulk structures, quantum wells with varying thickness, and semiconductor alloys.

cond-mat.mes-hall↗