Dr Miguel Cruz Irisson

@article{Gonz\'{a}lez-Mac\'{i}as_2018,

title = {Lithium effects on the mechanical and electronic properties of germanium nanowires},

author = {A Gonz\'{a}lez-Mac\'{i}as and F Salazar and A Miranda and A Trejo-Ba\~{n}os and L A P\'{e}rez and E Carvajal and M Cruz-Irisson},

url = {https://dx.doi.org/10.1088/1361-6528/aaaad4},

doi = {10.1088/1361-6528/aaaad4},

year  = {2018},

date = {2018-02-01},

journal = {Nanotechnology},

volume = {29},

number = {15},

pages = {154004},

publisher = {IOP Publishing},

abstract = {Semiconductor nanowire arrays promise rapid development of a new generation of lithium (Li) batteries because they can store more Li atoms than conventional crystals due to their large surface areas. During the charge\textendashdischarge process, the electrodes experience internal stresses that fatigue the material and limit the useful life of the battery. The theoretical study of electronic and mechanical properties of lithiated nanowire arrays allows the designing of electrode materials that could improve battery performance. In this work, we present a density functional theory study of the electronic band structure, formation energy, binding energy, and Young’s modulus (Y) of hydrogen passivated germanium nanowires (H\textendashGeNWs) grown along the [111] and [001] crystallographic directions with surface and interstitial Li atoms. The results show that the germanium nanowires (GeNWs) with surface Li atoms maintain their semiconducting behavior but their energy gap size decreases when the Li concentration grows. In contrast, the GeNWs can have semiconductor or metallic behavior depending on the concentration of the interstitial Li atoms. On the other hand, Y is an indicator of the structural changes that GeNWs suffer due to the concentration of Li atoms. For surface Li atoms, Y stays almost constant, whereas for interstitial Li atoms, the Y values indicate important structural changes in the GeNWs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{C8DT00355F,

title = {Lithium effect on the electronic properties of porous silicon for energy storage applications: a DFT study},

author = {I. Gonz\'{a}lez and A. N. Sosa and A. Trejo and M. Calvino and A. Miranda and M. Cruz-Irisson},

url = {http://dx.doi.org/10.1039/C8DT00355F},

doi = {10.1039/C8DT00355F},

year  = {2018},

date = {2018-01-01},

journal = {Dalton Trans.},

volume = {47},

issue = {22},

pages = {7505-7514},

publisher = {The Royal Society of Chemistry},

abstract = {Theoretical studies on the effect of Li on the electronic properties of porous silicon are still scarce; these studies could help us in the development of Li-ion batteries of this material which overcomes some limitations that bulk silicon has. In this work, the effect of interstitial and surface Li on the electronic properties of porous Si is studied using the first-principles density functional theory approach and the generalised gradient approximation. The pores are modeled by removing columns of atoms of an otherwise perfect Si crystal, dangling bonds of all surfaces are passivated with H atoms, and then Li is inserted on interstitial positions on the pore wall and compared with the replacement of H atoms with Li. The results show that the interstitial Li creates effects similar to n-type doping where the Fermi level is shifted towards the conduction band with band crossings of the said level thus acquiring metallic characteristics. The surface Li introduces trap-like states in the electronic band structures which increase as the number of Li atom increases with a tendency to become metallic. These results could be important for the application of porous Si nanostructures in Li-ion batteries technology.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{CUEVAS2018268,

title = {First principles band gap engineering of [1 1 0] oriented 3C-SiC nanowires},

author = {Jos\'{e} Luis Cuevas and Francisco Santiago and Jes\'{u}s Ram\'{i}rez and Alejandro Trejo and \'{A}lvaro Miranda and Luis Antonio P\'{e}rez and Miguel Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S0927025617305712},

doi = {https://doi.org/10.1016/j.commatsci.2017.10.021},

issn = {0927-0256},

year  = {2018},

date = {2018-01-01},

journal = {Computational Materials Science},

volume = {142},

pages = {268-276},

abstract = {Silicon carbide nanowires offer excellent opportunities for technological applications under harsh environmental conditions, however, the 3C-SiC polytype nanowires, grown along the [1 1 0] crystallographic direction, have been rarely studied, as well as the effects of the surface passivation on their physical properties. This work addresses the effects of hydrogen passivation on the electronic band gap of silicon carbide nanowires (SiCNWs) grown along the [1 1 0] direction by means of Density Functional Theory. We compare the electronic properties of fully hydrogen-passivated SiCNWs in comparison to those of SiCNWs with a mixed passivation of oxygen and hydrogen by changing some of the surface dihydrides with SiOSi or COC bonds. The results show that regardless of the diameter and passivation, most of the nanowires have a direct band gap which suggests an increased optical activity. The surface COC bonds reduce the electronic band gap energy compared to that of the fully H-terminated phase, while the nanowires with SiOSi bonds have a larger band gap. The calculation of formation energies shows that the oxygen increases the chemical stability of the SiCNWs. These results indicate the possibility of band gap engineering on SiC nanostructures through surface passivation.},

keywords = {DFT, Formation energy, SiC nanowires, Surface passivation},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1002/qua.25713,

title = {Quantum confinement effects on the harmful-gas-sensing properties of silicon nanowires},

author = {Francisco Santiago and \'{A}lvaro Miranda and Alejandro Trejo and Fernando Salazar and Eliel Carvajal and Miguel Cruz-Irisson and Luis A. P\'{e}rez},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/qua.25713},

doi = {https://doi.org/10.1002/qua.25713},

year  = {2018},

date = {2018-01-01},

journal = {International Journal of Quantum Chemistry},

volume = {118},

number = {20},

pages = {e25713},

abstract = {Abstract In this work, the effects of the adsorption of different toxic gas molecules CO, NO, NO2, and SO2 on the electronic structure of hydrogen-passivated, [111]-oriented, silicon nanowires (H-SiNWs), are studied through density functional theory. To analyze the effects of quantum confinement, three nanowire diameters are considered. The results show that the adsorption energies are almost independent of the nanowire diameter with NO2 being the most strongly adsorbed molecule (∼3.44 eV). The electronic structure of small-diameter H-SiNWs is modified due to the creation of isolated defect-like states on molecule adsorption. However, these discrete levels are eventually hybridized with the former nanowire states as the nanowire diameter increases and quantum confinement effects become less evident. Hence, there is a range of small nanowire diameters with distinctive band gaps and adsorption energies for each molecule species.},

keywords = {Density Functional Theory, Nanowires, Sensors, silicon, toxic gases},

pubstate = {published},

tppubtype = {article}

}

@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{Pilo2017,

title = {Bidimensional perovskite systems for spintronic applications},

author = {Jorge Pilo and \'{A}lvaro Miranda and Alejandro Trejo and Eliel Carvajal and Miguel Cruz-Irisson},

url = {https://doi.org/10.1007/s00894-017-3483-9},

doi = {10.1007/s00894-017-3483-9},

issn = {0948-5023},

year  = {2017},

date = {2017-10-24},

journal = {Journal of Molecular Modeling},

volume = {23},

number = {11},

pages = {322},

abstract = {The half-metallic behavior of the perovskite Sr2FeMoO6 (SFMO) suggests that this material could be used in spintronic applications. Indeed, SFMO could be an attractive material for multiple applications due to the possibility that its electronic properties could be changed by modifying its spatial confinement or the relative contents of its constituent transition metals. However, there are no reports of theoretical studies on the properties of confined SFMOs with different transition metal contents. In this work, we studied the electronic properties of SFMO slabs using spin-polarized first-principles density functional theory along with the Hubbard-corrected local density approximation and a supercell scheme. We modeled three insulated SFMO slabs with Fe:Mo atomic ratios of 1:1, 1:0, and 0:1; all with free surfaces parallel to the (001) crystal plane. The results show that the half-metallicity of the SFMO is lost upon confinement and the material becomes a conductor, regardless of the ratio of Fe to Mo. It was also observed that the magnetic moment of the slab is strongly influenced by the oxygen atoms. These results could prove useful in attempts to apply SFMOs in fields other than spintronics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{deSantiago2017,

title = {Band-gap engineering of halogenated silicon nanowires through molecular doping},

author = {Francisco Santiago and Alejandro Trejo and Alvaro Miranda and Eliel Carvajal and Luis Antonio P\'{e}rez and Miguel Cruz-Irisson},

url = {https://doi.org/10.1007/s00894-017-3484-8},

doi = {10.1007/s00894-017-3484-8},

issn = {0948-5023},

year  = {2017},

date = {2017-10-16},

journal = {Journal of Molecular Modeling},

volume = {23},

number = {11},

pages = {314},

abstract = {In this work, we address the effects of molecular doping on the electronic properties of fluorinated and chlorinated silicon nanowires (SiNWs), in comparison with those corresponding to hydrogen-passivated SiNWs. Adsorption of n-type dopant molecules on hydrogenated and halogenated SiNWs and their chemisorption energies, formation energies, and electronic band gap are studied by using density functional theory calculations. The results show that there are considerable charge transfers and strong covalent interactions between the dopant molecules and the SiNWs. Moreover, the results show that the energy band gap of SiNWs changes due to chemical surface doping and it can be further tuned by surface passivation. We conclude that a molecular based ex-situ doping, where molecules are adsorbed on the surface of the SiNW, can be an alternative path to conventional doping.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Solano2017,

title = {DFT study of anisotropy effects on the electronic properties of diamond nanowires with nitrogen-vacancy center},

author = {Jes\'{u}s Ram\'{i}rez Solano and Alejandro Trejo Ba\~{n}os and \'{A}lvaro Miranda Dur\'{a}n and Eliel Carvajal Quiroz and Miguel Cruz Irisson},

url = {https://doi.org/10.1007/s00894-017-3462-1},

doi = {10.1007/s00894-017-3462-1},

issn = {0948-5023},

year  = {2017},

date = {2017-09-26},

journal = {Journal of Molecular Modeling},

volume = {23},

number = {10},

pages = {292},

abstract = {In the development of quantum computing and communications, improvements in materials capable of single photon emission are of great importance. Advances in single photon emission have been achieved experimentally by introducing nitrogen-vacancy (N-V) centers on diamond nanostructures. However, theoretical modeling of the anisotropic effects on the electronic properties of these materials is almost nonexistent. In this study, the electronic band structure and density of states of diamond nanowires with N-V defects were analyzed through first principles approach using the density functional theory and the supercell scheme. The nanowires were modeled on two growth directions [001] and [111]. All surface dangling bonds were passivated with hydrogen (H) atoms. The results show that the N-V introduces multiple trap states within the energy band gap of the diamond nanowire. The energy difference between these states is influenced by the growth direction of the nanowires, which could contribute to the emission of photons with different wavelengths. The presence of these trap states could reduce the recombination rate between the conduction and the valence band, thus favoring the single photon emission.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Calvino2016,

title = {Modeling the effects of Si-X (X = F, Cl) bonds on the chemical and electronic properties of Si-surface terminated porous 3C-SiC},

author = {Marbella Calvino and Alejandro Trejo and Margarita Clarisaila Cris\'{o}stomo and Mar\'{i}a Isabel Iturrios and Eliel Carvajal and M Cruz-Irisson},

url = {https://doi.org/10.1007/s00214-016-1861-5},

doi = {10.1007/s00214-016-1861-5},

issn = {1432-2234},

year  = {2016},

date = {2016-03-26},

journal = {Theoretical Chemistry Accounts},

volume = {135},

number = {4},

pages = {104},

abstract = {Porous silicon carbide offers a great potential as a sensor material for applications in medicine and energetics; however, the theoretical chemical characterization of its surface is almost nonexistent, and a correct understanding of its chemical properties could lead to the development of better applications of this nanostructure. Hence, a study of the effects of different passivation agents on the structure and electronic properties of porous silicon carbide by means of density functional theory and the supercell technique was developed. The porous structures were modeled by removing columns of atoms of an otherwise perfect SiC crystal in the [001] direction, so that the porous structure exhibits a surface exclusively composed of Si atoms (Si-rich) using different surface passivation agents, such as hydrogen (H), fluoride (F) and chloride (Cl). The results demonstrate that all of the passivation schemes exhibit an irregular band gap energy evolution due to a hybridization change of the surface. The structural analysis shows a great dependence of the bond characteristics on the electronegativity of the bonded atoms, and all of the structural and electronic changes could be explained due to steric effects. These results could be important in the characterization of pSiC because they provide insight into the most stable surface configurations and their electronic structures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{TREJO2016215,

title = {Optical vibrational modes of Ge nanowires: A computational approach},

author = {A. Trejo and A. Miranda and L. K. Toscano-Medina and R. V\'{a}zquez-Medina and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S0167931716302258},

doi = {https://doi.org/10.1016/j.mee.2016.04.024},

issn = {0167-9317},

year  = {2016},

date = {2016-01-01},

journal = {Microelectronic Engineering},

volume = {159},

pages = {215-220},

abstract = {Although Ge nanowires (GeNWs) have been extensively studied in the last decade the information about their vibrational modes is still scarce, their correct comprehension could hasten the development of new microelectronic technologies, therefore, in this work we aimed to study the vibrational properties, Raman and IR and spectrum of GeNWs using the first principles density functional perturbation theory. The nanowires are modelled in the [001] direction and all dangling bonds are passivated with H and Cl atoms. Results show that the vibrational modes can be classified in three frequency intervals, a low frequency one (between 0 and 300cm−1) of mainly GeGe vibrations, and two of GeH bending and stretching vibrations (400\textendash500cm−1 and 2000cm−1, respectively). There is a shift of the highest optical modes of GeGe vibrations compared to their bulk counterparts due to phonon confinement effects, however it is masked by some GeH bond bending modes as demonstrated by the IR and Raman responses. The Cl passivated case shows a larger number of modes at lower frequencies due to the higher mass of Cl compared to H, which in turn reduces the red shift of the highest optical modes frequencies. These results could be important for the characterization of GeNWs with different surface passivations.},

note = {Micro/Nano Devices and Systems 2015},

keywords = {Density functional perturbation theory, Germanium nanowires, Phonons, Raman spectrum},

pubstate = {published},

tppubtype = {article}

}

@article{PILO2016110,

title = {Effect of the transition metal ratio on bulk and thin slab double perovskite Sr2FeMoO6},

author = {J. Pilo and A. Trejo and E. Carvajal and R. Oviedo-Roa and M. Cruz-Irisson and O. Navarro},

url = {https://www.sciencedirect.com/science/article/pii/S0167931716302283},

doi = {https://doi.org/10.1016/j.mee.2016.04.026},

issn = {0167-9317},

year  = {2016},

date = {2016-01-01},

journal = {Microelectronic Engineering},

volume = {162},

pages = {110-113},

abstract = {Double perovskites are promising materials for multiple applications on microelectronics, specially on magnetic devices development. Perhaps the most interesting one is the double perovskite Sr2FeMoO6 since its magnetic properties differ from that of other related simple perovskites: SrFeO3 and SrMoO3. In this work the evolution of the electronic properties and the magnetic moment distribution as a function of the Fe/Mo ratio in bulk and a thin slab of Sr2FeMoO6 was studied. The thin slab was constructed keeping free surfaces parallel to the (001) crystalline planes with different thickness and compositions. All calculations were made in the Density Functional Theory scheme in the Generalized Gradient Approximation, using the Perdew-Burke-Ernzerhof functional, as implemented in the DMol3 code. After being geometry optimized, the electronic Density of States and band structure were calculated, as well as the magnetic moment distribution, for each modeled system. Essential results are as follows: for the bulk cases it was found that half-metallic behavior which characterizes the stoichiometric double perovskite changes if the compound becomes molybdenum or iron rich; for the slab is remarkable the induction of magnetic moments, owed to the corresponding to iron atoms, over their neighbor atoms.},

keywords = {Density Functional Theory, electronic properties, Magnetic properties, Perovskites, Thin slabs},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1504/IJNT.2015.067212,

title = {Electronic structure and optical vibrational modes of 3C\textendashSiC nanowires},

author = {Alejandro Trejo and Miguel Ojeda and Jos\'{e} Luis Cuevas and \'{A}lvaro Miranda and Luis A. P\'{e}rez and Miguel Cruz\textendashIrisson},

url = {https://www.inderscienceonline.com/doi/abs/10.1504/IJNT.2015.067212},

doi = {10.1504/IJNT.2015.067212},

year  = {2015},

date = {2015-01-01},

journal = {International Journal of Nanotechnology},

volume = {12},

number = {3-4},

pages = {275-284},

abstract = {The electronic structure and vibrational optical modes of silicon carbide nanowires (SiCNWs) were studied using the first principles density functional theory. The nanowires were modelled along the [111] direction using the supercell technique passivating all the surface dangling bonds with H atoms, OH radicals and a combination of both. Results show that the full OH passivation lowers the band gap energy compared to the full H passivation owing to C\textendashOH surface states. A shift of the highest optical vibrational modes of Si and C to lower frequency values compared to their bulk counterparts was observed in accordance with phonon confinement scheme.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Calvino2014,

title = {DFT Study of the Electronic Structure of Cubic-SiC Nanopores with a C-Terminated Surface},

author = {Marbella Calvino and Alejandro Trejo and Mar\'{i}a Isabel Iturrios and Margarita Clarisaila Cris\'{o}stomo and Eliel Carvajal and M Cruz-Irisson},

url = {https://doi.org/10.1155/2014/471351},

doi = {10.1155/2014/471351},

issn = {1687-4110},

year  = {2014},

date = {2014-06-01},

journal = {Journal of Nanomaterials},

volume = {2014},

pages = {471351},

publisher = {Hindawi Publishing Corporation},

abstract = {A study of the dependence of the electronic structure and energetic stability on the chemical surface passivation of cubic porous silicon carbide (pSiC) was performed using density functional theory (DFT) and the supercell technique. The pores were modeled by removing atoms in the [001] direction to produce a surface chemistry composed of only carbon atoms (C-phase). Changes in the electronic states of the porous structures were studied by using different passivation schemes: one with hydrogen (H) atoms and the others gradually replacing pairs of H atoms with oxygen (O) atoms, fluorine (F) atoms, and hydroxide (OH) radicals. The results indicate that the band gap behavior of the C-phase pSiC depends on the number of passivation agents (other than H) per supercell. The band gap decreased with an increasing number of F, O, or OH radical groups. Furthermore, the influence of the passivation of the pSiC on its surface relaxation and the differences in such parameters as bond lengths, bond angles, and cell volume are compared between all surfaces. The results indicate the possibility of nanostructure band gap engineering based on SiC via surface passivation agents.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{TREJO201414,

title = {Theoretical approach to the phonon modes and specific heat of germanium nanowires},

author = {A. Trejo and L. L\'{o}pez-Palacios and R. V\'{a}zquez-Medina and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S0921452614003706},

doi = {https://doi.org/10.1016/j.physb.2014.05.005},

issn = {0921-4526},

year  = {2014},

date = {2014-01-01},

journal = {Physica B: Condensed Matter},

volume = {453},

pages = {14-18},

abstract = {The phonon modes and specific heat of Ge nanowires were computed using a first principles density functional theory scheme with a generalized gradient approximation and finite-displacement supercell algorithms. The nanowires were modeled in three different directions: [001], [111], and [110], using the supercell technique. All surface dangling bonds were saturated with Hydrogen atoms. The results show that the specific heat of the GeNWs at room temperature increases as the nanowire diameter decreases, regardless the orientation due to the phonon confinement and surface passivation. Also the phonon confinement effects could be observed since the highest optical phonon modes in the Ge vibration interval shifted to a lower frequency compared to their bulk counterparts.},

note = {Low-Dimensional Semiconductor Structures - A part of the XXII International Material Research Congress (IMRC 2013)},

keywords = {Germanium, Nanowires, Phonons, Specific Heat},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1063/1.4878289,

title = {Electronic states of lithium passivated germanium nanowires: An ab-initio study},

author = {A Trejo and E. Carvajal and R. V\'{a}zquez-Medina and M. Cruz-Irisson},

url = {https://aip.scitation.org/doi/abs/10.1063/1.4878289},

doi = {10.1063/1.4878289},

year  = {2014},

date = {2014-01-01},

journal = {AIP Conference Proceedings},

volume = {1598},

number = {1},

pages = {114-117},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Trejo2013,

title = {Ab-initio study of anisotropic and chemical surface modifications of $beta$-SiC nanowires},

author = {Alejandro Trejo and Jos\'{e} Luis Cuevas and Fernando Salazar and Eliel Carvajal and Miguel Cruz-Irisson},

url = {https://doi.org/10.1007/s00894-012-1605-y},

doi = {10.1007/s00894-012-1605-y},

issn = {0948-5023},

year  = {2013},

date = {2013-05-01},

journal = {Journal of Molecular Modeling},

volume = {19},

number = {5},

pages = {2043-2048},

abstract = {The electronic band structure and electronic density of states of cubic SiC nanowires (SiCNWs) in the directions [001], [111], and [112] were studied by means of Density Functional Theory (DFT) based on the generalized gradient approximation and the supercell technique. The surface dangling bonds were passivated using hydrogen (H) atoms and OH radicals in order to study the effects of this passivation on the electronic states of the SiCNWs. The calculations show a clear dependence of the electronic properties of the SiCNWs on the quantum confinement, orientation, and chemical passivation of the surface. In general, surface passivation with either H or OH radicals removes the dangling bond states from the band gap, and OH saturation appears to produce a smaller band gap than H passivation. An analysis of the atom-resolved density of states showed that there is substantial charge transfer between the Si and O atoms in the OH-terminated case, which reduces the band gap compared to the H-terminated case, in which charge transfer mainly occurs between the Si and C atoms.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{TREJO201310,

title = {Anisotropic effects on the radial breathing mode of silicon nanowires: An ab initio study},

author = {A. Trejo and R. Vazquez-Medina and G. I. Duchen and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S1386947713000404},

doi = {https://doi.org/10.1016/j.physe.2013.02.006},

issn = {1386-9477},

year  = {2013},

date = {2013-01-01},

journal = {Physica E: Low-dimensional Systems and Nanostructures},

volume = {51},

pages = {10-14},

abstract = {The effect of orientation on the frequency of the radial breathing mode (RBM) of silicon nanowires (SiNWs) is investigated by means of the first principles Density Functional Theory approach through the generalized gradient approximation. We compare the RBM frequency of SiNWs orientated in three different directions, [001], [111], and [110]. The RBM is observed by the calculation of the phonon band structure and density of states of the SiNWs through the supercell finite displacement method. Results show that the SiNWs are stable in the three chosen directions since there are no negative frequencies in their phonon band structure and density of states. A clear dependence of the RBM frequency with respect to the growth direction of the nanowires and the phonon confinement was observed as the RBM frequency decreased with an inverse power law in each nanowire direction, with the fitting parameters dependent on the growth direction. These results are important since they could be used as a fingerprint to identify them within different spectroscopy techniques such as Raman.},

note = {IMRC 2012},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{molecules18044776,

title = {Computational Modeling of the Size Effects on the Optical Vibrational Modes of H-Terminated Ge Nanostructures},

author = {Alejandro Trejo and Miguel Cruz-Irisson},

url = {https://www.mdpi.com/1420-3049/18/4/4776},

doi = {10.3390/molecules18044776},

issn = {1420-3049},

year  = {2013},

date = {2013-01-01},

journal = {Molecules},

volume = {18},

number = {4},

pages = {4776--4785},

abstract = {The vibrational dispersion relations of porous germanium (pGe) and germanium nanowires (GeNWs) were calculated using the ab initio density functional perturbation theory with a generalized gradient approximation with norm-conserving pseudopotentials. Both pores and nanowires were modeled using the supercell technique. All of the surface dangling bonds were saturated with hydrogen atoms. To address the difference in the confinement between the pores and the nanowires, we calculated the vibrational density of states of the two materials. The results indicate that there is a slight shift in the highest optical mode of the Ge-Ge vibration interval in all of the nanostructures due to the phonon confinement effects. The GeNWs exhibit a reduced phonon confinement compared with the porous Ge due to the mixed Ge-dihydride vibrational modes around the maximum bulk Ge optical mode of approximately 300 cm−1; however, the general effects of such confinements could still be noticed, such as the shift to lower frequencies of the highest optical mode belonging to the Ge vibrations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Trejo2012,

title = {Computational simulation of the effects of oxygen on the electronic states of hydrogenated 3C-porous SiC},

author = {Alejandro Trejo and Marbella Calvino and Estrella Ramos and Miguel Cruz-Irisson},

url = {https://doi.org/10.1186/1556-276X-7-471},

doi = {10.1186/1556-276X-7-471},

issn = {1556-276X},

year  = {2012},

date = {2012-08-22},

journal = {Nanoscale Research Letters},

volume = {7},

number = {1},

pages = {471},

abstract = {A computational study of the dependence of the electronic band structure and density of states on the chemical surface passivation of cubic porous silicon carbide (pSiC) was performed using ab initio density functional theory and the supercell method. The effects of the porosity and the surface chemistry composition on the energetic stability of pSiC were also investigated. The porous structures were modeled by removing atoms in the [001] direction to produce two different surface chemistries: one fully composed of silicon atoms and one composed of only carbon atoms. The changes in the electronic states of the porous structures as a function of the oxygen (O) content at the surface were studied. Specifically, the oxygen content was increased by replacing pairs of hydrogen (H) atoms on the pore surface with O atoms attached to the surface via either a double bond (Xthinspace=thinspaceO) or a bridge bond (X-O-X, Xthinspace=thinspaceSi or C). The calculations show that for the fully H-passivated surfaces, the forbidden energy band is larger for the C-rich phase than for the Si-rich phase. For the partially oxygenated Si-rich surfaces, the band gap behavior depends on the O bond type. The energy gap increases as the number of O atoms increases in the supercell if the O atoms are bridge-bonded, whereas the band gap energy does not exhibit a clear trend if O is double-bonded to the surface. In all cases, the gradual oxygenation decreases the band gap of the C-rich surface due to the presence of trap-like states.},

keywords = {},

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{CUEVAS20128360,

title = {Ab-initio modeling of oxygen on the surface passivation of 3CSiC nanostructures},

author = {J. L. Cuevas and A. Trejo and M. Calvino and E. Carvajal and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S0169433212006289},

doi = {https://doi.org/10.1016/j.apsusc.2012.03.175},

issn = {0169-4332},

year  = {2012},

date = {2012-01-01},

journal = {Applied Surface Science},

volume = {258},

number = {21},

pages = {8360-8365},

abstract = {In this work the effect of OH on the electronic states of H-passivated 3CSiC nanostructures, was studied by means of Density Functional Theory. We compare the electronic band structure for a [111]-oriented nanowire with total H, OH passivation and a combination of both. Also the electronic states of a porous silicon carbide case (PSiC) a C-rich pore surface in which the dangling bonds on the surface are saturated with H and OH was studied. The calculations show that the surface replacement of H with OH radicals is always energetically favorable and more stable. In all cases the OH passivation produced a similar effect than the H passivation, with electronic band gap of lower energy value than the H-terminated phase. When the OH groups are attached to C atoms, the band gap feature is changed from direct to indirect. The results indicate the possibility of band gap engineering on SiC nanostructures through the surface passivation species.},

note = {VII International Workshop on Semiconductor Surface Passivation, KRAK\'{O}W, POLAND, September 11 - 15, 2011},

keywords = {Density Functional Theory, Nanowires, Porous semiconductors, Silicon carbide},

pubstate = {published},

tppubtype = {article}

}

@article{MIRANDA20121230,

title = {Interconnection effects on the electronic and optical properties of Ge nanostructures: A semi-empirical approach},

author = {A. Miranda and A. Trejo and E. Canadell and R. Rurali and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S1386947712000318},

doi = {https://doi.org/10.1016/j.physe.2012.01.017},

issn = {1386-9477},

year  = {2012},

date = {2012-01-01},

journal = {Physica E: Low-dimensional Systems and Nanostructures},

volume = {44},

number = {7},

pages = {1230-1235},

abstract = {A supercell model is applied to a semi-empirical sp3s⁎ tight-binding (TB) approach to calculate the electronic band gap and imaginary part of the dielectric function of two Ge nanostructures\textemdashordered arrays of pores and stand-alone nanowires\textemdashand one example of their interconnections. The pores are modeled by removing columns of Ge atoms in the [001] direction. The results of the variation band gap are compared with those obtained by TB-sp3, TB-sp3d5s⁎, density functional theory (DFT), and experimental data. The imaginary part of the dielectric function is calculated by including both intra-atomic and inter-atomic dipole matrices using (for both) the interconnected and free standing (chessboard-like) models for the Ge skeleton. The calculation shows that although the intra-atomic matrix elements are small in magnitude a quantitative treatment of the optical absorption spectrum of Ge nanostructures may not be possible without the inclusion of these matrix elements. Finally, the calculations confirm that also ordered porous germanium (PGe) show a clear quantum confinement signature, even though the wave functions could in principle behave like delocalized Bloch states.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{TREJO2012141,

title = {Phonon band structure of porous Ge from ab initio supercell calculation},

author = {A. Trejo and J. L. Cuevas and R. V\'{a}zquez-Medina and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S016793171100503X},

doi = {https://doi.org/10.1016/j.mee.2011.05.007},

issn = {0167-9317},

year  = {2012},

date = {2012-01-01},

journal = {Microelectronic Engineering},

volume = {90},

pages = {141-144},

abstract = {The phonon band structures for porous Ge (PGe) are performed by means of full ab initio calculations. The supercell technique is used and ordered pores are produced by removing columns of Ge atoms from their crystalline structures. The nanostructures are fully relaxed in order to obtain the minimum energy and avoid negative frequencies derived from instabilities of the system. The phonon dispersion and phonon density of states were studied using the Density Functional Theory through the finite displacement algorithm. The results show for the dehydrogenated PGe case a notable shift of the highest optical mode towards lower frequencies with respect to the bulk crystalline Ge. This fact is in agreement with the experimental data such as Raman scattering.},

note = {Micro\&Nano 2010},

keywords = {Density Functional Theory, Phonons, porous germanium, Supercell approach},

pubstate = {published},

tppubtype = {article}

}

@article{TREJO201292,

title = {Phonon optical modes and electronic properties in diamond nanowires},

author = {A. Trejo and A. Miranda and L. Ni\~{n}o Rivera and A. D\'{i}az-M\'{e}ndez and M. Cruz-Irisson},

url = {https://www.sciencedirect.com/science/article/pii/S016793171100476X},

doi = {https://doi.org/10.1016/j.mee.2011.04.052},

issn = {0167-9317},

year  = {2012},

date = {2012-01-01},

journal = {Microelectronic Engineering},

volume = {90},

pages = {92-95},

abstract = {A local bond-polarization model based on the displacement\textendashdisplacement Green’s function and the Born potential are applied to study the confined optical phonons and Raman scattering of diamond nanowires (DNWs). Also, the electronic band structure of DNWs are investigated by means of a semi-empirical tight-binding approach and compared with density functional theory within local density approximation. The supercell technique is applied to model DNWs along [001] direction preserving the crystalline diamond atomic structure. The results of both phonons and electrons show a clear quantum confinement signature. Moreover, the highest energy Raman peak shows a shift towards low frequencies respect to the bulk crystalline diamond, in agreement with experimental data.},

note = {Micro\&Nano 2010},

keywords = {Diamond, Nanowires, Phonons, Raman scattering, Tight-binding},

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}

}