Dr Alejandro Trejo Baños

@article{GONZALEZ2018420,

title = {Effects of surface and confinement on the optical vibrational modes and dielectric function of 3C porous silicon carbide: An ab-initio study},

author = {I. Gonz\'{a}lez and A. Trejo and M. Calvino and A. Miranda and F. Salazar and E. Carvajal and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S0921452618303569},

doi = {https://doi.org/10.1016/j.physb.2018.05.024},

issn = {0921-4526},

year  = {2018},

date = {2018-01-01},

journal = {Physica B: Condensed Matter},

volume = {550},

pages = {420-427},

abstract = {Nanoporous silicon carbide is an interesting material with multiple potential applications, especially in supercapacitors, while there are many experimental investigations on the properties of this material, theoretical studies on its vibrational and optical properties are still scarce. This work studies the effect of quantum confinement on the dielectric function and optical vibrational modes of 3C porous silicon carbide from ab-initio calculations using density functional theory and density functional perturbation theory. The porous structures are modelled in the [001] direction by removing columns of atoms of a perfect Si crystal, obtaining two surface configurations: one with only C atoms and another one with Si atoms. Results show that the optical phonon modes of Si and C undergo a shift towards lower frequencies compared to their bulk counterparts due to phonon confinement effects. However, this shift is masked by H bending vibrations. Also, a surface H exchange process is observed on the Si-rich pore surface due to bond stretching and bending vibrations. The dielectric function analysis shows an increased optical activity in the porous cases due to a shift of the conduction band minimum towards gamma point for the C-rich case and high porosity Si-rich case, owing to quantum confinement effects. These results could be important for the applications of these nanostructures devices such as sensors and UV detectors.},

keywords = {DFPT, Dielectric function, Phonon optical modes, Porous silicon carbide},

pubstate = {published},

tppubtype = {article}

}

@article{CALVINO20121482,

title = {A Density Functional Theory study of the chemical surface modification of β-SiC nanopores},

author = {M. Calvino and A. Trejo and J. L. Cuevas and E. Carvajal and G. I. Duch\'{e}n and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S0921510712000918},

doi = {https://doi.org/10.1016/j.mseb.2012.02.009},

issn = {0921-5107},

year  = {2012},

date = {2012-01-01},

journal = {Materials Science and Engineering: B},

volume = {177},

number = {16},

pages = {1482-1486},

abstract = {The dependence of the electronic band structure and density of states on the chemical surface passivation of cubic porous silicon carbide (PSiC) is investigated by means of the ab-initio Density Functional Theory and the supercell method in which pores with different sizes and morphologies were created. The porous structures were modeled by removing atoms in the [001] direction producing two different surface chemistries; one with both Silicon (Si) and Carbon (C) atoms and the other with only Si or C atoms. The changes in the electronic band gap due to a Si-rich and C-rich phase in the porous surfaces are studied with two kind of surface passivation, one with hydrogen atoms and other with a combination between hydrogen and oxygen atoms. The calculations show that for the hydrogenated case, the band gap is larger for the C-rich than for the Si-rich case. For the partial oxygenation the tendency is contrary, by decreasing and increasing the band gap for the C-rich and Si-rich configuration, respectively, according to the percentage of oxygen in the pore surface.},

note = {Advances in Semiconducting Materials},

keywords = {Density Functional Theory, Porous silicon carbide, Surface passivation},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/qua.22647,

title = {Chemical surface passivation of 3C-SiC nanocrystals: A first-principle study},

author = {A. Trejo and M. Calvino and M. Cruz-Irisson},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/qua.22647},

doi = {https://doi.org/10.1002/qua.22647},

year  = {2010},

date = {2010-01-01},

journal = {International Journal of Quantum Chemistry},

volume = {110},

number = {13},

pages = {2455-2461},

abstract = {Abstract The effect of the chemical surface passivation, with hydrogen atoms, on the energy band gap of porous cubic silicon carbide (PSiC) was investigated. The pores are modeled by means of the supercell technique, in which columns of Si and/or C atoms are removed along the [001] direction. Within this supercell model, morphology effects can be analyzed in detail. The electronic band structure is performed using the density functional theory based on the generalized gradient approximation. Two types of pores are studied: C-rich and Si-rich pores surface. The enlargement of energy band gap is greater in the C-rich than Si-rich pores surface. This supercell model emphasizes the interconnection between 3C-SiC nanocrystals, delocalizing the electronic states. However, the results show a clear quantum confinement signature, which is contrasted with that of nanowire systems. The calculation shows a significant response to changes in surface passivation with hydrogen. The chemical tuning of the band gap opens the possibility plenty applications in nanotechnology. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 110:2455\textendash2461, 2010},

keywords = {Density Functional Theory, Porous silicon carbide, silicon carbide nanowires},

pubstate = {published},

tppubtype = {article}

}