J. D. Castaño-Yepes | Searcharxiv

arXiv2018

Porosity and roughness determination of porous silicon thin films by genetic algorithms

The problem of determining the porous silicon (PSi) optical constants, thickness, porosity, and surface quality using just reflectance data is board employing evolutionary algorithms. The reflectance measurements were carried out of PSi films over crystalline silicon (c-Si) substrate, and the fitting procedure was done by using a genetic algorithm. The PSi is treated as a mixture of c-Si and air. Therefore, its effective optical constants can be correlated with the porosity trough effective medium approximation (EMA). The results show that genetic fitting has a good match with the experimental measurements (Near UV-Vis reflectance) and the thickness obtained by scanning electron microscopy (SEM).

cond-mat.mtrl-sci↗

arXiv2017

A comparative study on heat capacity, magnetization and magnetic susceptibility for a GaAs quantum dot with asymmetric confinement

In this work, thermal and magnetic properties for an electron with cylindrical confinement in presence of external electric and magnetic fields have been investigated. We found that the corresponding time-independent Schrödinger equation can be separated into the product of the radially symmetric and an axial equation. Moreover, we have obtained a quasi-exact expression for the energy spectrum of the system in terms of the exact solutions for the radial equation and an approximation up to first order for the axial equation. We have calculated the well-known thermal and magnetic properties as the heat capacity, magnetization and the magnetic susceptibility via the canonical partition function. We found that our results for thermal and magnetic properties differ significantly from results previously obtained by others authors (by Gumber et. al.). Moreover, our results are in agreement with the diamagnetic properties of GaAs.

cond-mat.mes-hall↗