2022
Cuevas, J. L.; Ojeda, M.; Calvino, M.; Trejo, A.; Salazar, F.; Miranda, A.; Perez, L. A.; Cruz-Irisson, M.
Theoretical approach to the phonon modes of GaSb nanowires Artículo de revista
En: Physica E: Low-dimensional Systems and Nanostructures, vol. 143, pp. 115372, 2022, ISSN: 1386-9477.
Resumen | Enlaces | BibTeX | Etiquetas: DFT, Gallium Antimonide, Nanowires, Phonons
@article{CUEVAS2022115372,
title = {Theoretical approach to the phonon modes of GaSb nanowires},
author = {J. L. Cuevas and M. Ojeda and M. Calvino and A. Trejo and F. Salazar and A. Miranda and L. A. Perez and M. Cruz-Irisson},
url = {https://www.sciencedirect.com/science/article/pii/S1386947722002077},
doi = {https://doi.org/10.1016/j.physe.2022.115372},
issn = {1386-9477},
year = {2022},
date = {2022-01-01},
journal = {Physica E: Low-dimensional Systems and Nanostructures},
volume = {143},
pages = {115372},
abstract = {Gallium Antimonide nanowires (GaSbNWs) have attracted much attention due to their possible applications in mid infrared detectors, however, there are only few theoretical investigations about this material and almost none regarding its vibrational properties. In this work the phonon modes of GaSbNWs were studied using the density functional theory with the finite displacement supercell scheme. The nanowires are modeled by removing atoms outside from a circumference along the [1 1 1] direction. All surface dangling bonds were passivated with hydrogen atoms. The results show that the expected red-shift of the highest frequency modes of GaSb are hindered by low frequency H bond bending modes. Three clearly distinguishable frequency intervals were observed: One with vibrations whose main contribution come from the Ga and Sb nanowire atoms, the second interval with main contributions from H bending modes and finally a high frequency interval where the main contributions come from H stretching modes. Also, it was observed that the radial breathing mode (RBM) decreases when the nanowire diameter increases, while the contrary tendency is observed with their specific heat (the specific heat increases as the nanowire diameter increases), except in the low temperature region where the lower diameters have higher specific heat values. These results could be important for the characterization of these nanowires with IR and Raman techniques.},
keywords = {DFT, Gallium Antimonide, Nanowires, Phonons},
pubstate = {published},
tppubtype = {article}
}
Gallium Antimonide nanowires (GaSbNWs) have attracted much attention due to their possible applications in mid infrared detectors, however, there are only few theoretical investigations about this material and almost none regarding its vibrational properties. In this work the phonon modes of GaSbNWs were studied using the density functional theory with the finite displacement supercell scheme. The nanowires are modeled by removing atoms outside from a circumference along the [1 1 1] direction. All surface dangling bonds were passivated with hydrogen atoms. The results show that the expected red-shift of the highest frequency modes of GaSb are hindered by low frequency H bond bending modes. Three clearly distinguishable frequency intervals were observed: One with vibrations whose main contribution come from the Ga and Sb nanowire atoms, the second interval with main contributions from H bending modes and finally a high frequency interval where the main contributions come from H stretching modes. Also, it was observed that the radial breathing mode (RBM) decreases when the nanowire diameter increases, while the contrary tendency is observed with their specific heat (the specific heat increases as the nanowire diameter increases), except in the low temperature region where the lower diameters have higher specific heat values. These results could be important for the characterization of these nanowires with IR and Raman techniques.
2016
Trejo, A.; Miranda, A.; Toscano-Medina, L. K.; Vázquez-Medina, R.; Cruz-Irisson, M.
Optical vibrational modes of Ge nanowires: A computational approach Artículo de revista
En: Microelectronic Engineering, vol. 159, pp. 215-220, 2016, ISSN: 0167-9317, (Micro/Nano Devices and Systems 2015).
Resumen | Enlaces | BibTeX | Etiquetas: Density functional perturbation theory, Germanium nanowires, Phonons, Raman spectrum
@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}
}
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 (400–500cm−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.
Escamilla, R.; Carvajal, E.; Cruz-Irisson, M.; Romero, M.; Gómez, R.; Marquina, V.; Galván, D. H.; Durán, A.
First-principles study of the structural, elastic, vibrational, thermodynamic and electronic properties of the Mo2B intermetallic under pressure Artículo de revista
En: Journal of Molecular Structure, vol. 1125, pp. 350-357, 2016, ISSN: 0022-2860.
Resumen | Enlaces | BibTeX | Etiquetas: Dimolybdenum boride, Electron density of states, High pressure, Phonons
@article{ESCAMILLA2016350,
title = {First-principles study of the structural, elastic, vibrational, thermodynamic and electronic properties of the Mo2B intermetallic under pressure},
author = {R. Escamilla and E. Carvajal and M. Cruz-Irisson and M. Romero and R. G\'{o}mez and V. Marquina and D. H. Galv\'{a}n and A. Dur\'{a}n},
url = {https://www.sciencedirect.com/science/article/pii/S0022286016306755},
doi = {https://doi.org/10.1016/j.molstruc.2016.07.004},
issn = {0022-2860},
year = {2016},
date = {2016-01-01},
urldate = {2016-01-01},
journal = {Journal of Molecular Structure},
volume = {1125},
pages = {350-357},
abstract = {The structural, elastic, vibrational, thermodynamic and electronic properties of the Mo2B intermetallic under pressure are assessed using first-principles calculations based on the generalized gradient approximation (GGA) proposed by Perdew-Wang (PW91). Our results show that the calculated structural parameters at a pressure of zero GPa are in good agreement with the available experimental data. The effect of high pressures on the lattice constants shows that the compression along the c-axis and along the a-axis are similar. The elastic constants were calculated using the static finite strain technique, and the bulk shear moduli are derived from the ideal polycrystalline aggregate. We find that the elastic constants, elastic modulus and hardness monotonically increase as a function of pressure; consequently, the structure is dynamically stable and tends from brittle to ductile behavior under pressure. The Debye temperature θD increases and the so-called Gru¨ neisen constant γ decreases due to stiffening of the crystal structure. The phonon dispersion curves were obtained using the direct method. Additionally, the internal energy (ΔE), the Helmholtz free energy (ΔF), the entropy (S) and the lattice contribution to the heat capacity Cv were calculated and analyzed with the help of the phonon dispersion curves. The N(EF) and the electron transfer between the B and Mo atoms increase as a function of pressure.},
keywords = {Dimolybdenum boride, Electron density of states, High pressure, Phonons},
pubstate = {published},
tppubtype = {article}
}
The structural, elastic, vibrational, thermodynamic and electronic properties of the Mo2B intermetallic under pressure are assessed using first-principles calculations based on the generalized gradient approximation (GGA) proposed by Perdew-Wang (PW91). Our results show that the calculated structural parameters at a pressure of zero GPa are in good agreement with the available experimental data. The effect of high pressures on the lattice constants shows that the compression along the c-axis and along the a-axis are similar. The elastic constants were calculated using the static finite strain technique, and the bulk shear moduli are derived from the ideal polycrystalline aggregate. We find that the elastic constants, elastic modulus and hardness monotonically increase as a function of pressure; consequently, the structure is dynamically stable and tends from brittle to ductile behavior under pressure. The Debye temperature θD increases and the so-called Gru¨ neisen constant γ decreases due to stiffening of the crystal structure. The phonon dispersion curves were obtained using the direct method. Additionally, the internal energy (ΔE), the Helmholtz free energy (ΔF), the entropy (S) and the lattice contribution to the heat capacity Cv were calculated and analyzed with the help of the phonon dispersion curves. The N(EF) and the electron transfer between the B and Mo atoms increase as a function of pressure.
2014
Trejo, A.; López-Palacios, L.; Vázquez-Medina, R.; Cruz-Irisson, M.
Theoretical approach to the phonon modes and specific heat of germanium nanowires Artículo de revista
En: Physica B: Condensed Matter, vol. 453, pp. 14-18, 2014, ISSN: 0921-4526, (Low-Dimensional Semiconductor Structures - A part of the XXII International Material Research Congress (IMRC 2013)).
Resumen | Enlaces | BibTeX | Etiquetas: Germanium, Nanowires, Phonons, Specific Heat
@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}
}
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.
2012
Trejo, A.; Cuevas, J. L.; Vázquez-Medina, R.; Cruz-Irisson, M.
Phonon band structure of porous Ge from ab initio supercell calculation Artículo de revista
En: Microelectronic Engineering, vol. 90, pp. 141-144, 2012, ISSN: 0167-9317, (Micro&Nano 2010).
Resumen | Enlaces | BibTeX | Etiquetas: Density Functional Theory, Phonons, porous germanium, Supercell approach
@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}
}
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.
Trejo, A.; Miranda, A.; Rivera, L. Niño; Díaz-Méndez, A.; Cruz-Irisson, M.
Phonon optical modes and electronic properties in diamond nanowires Artículo de revista
En: Microelectronic Engineering, vol. 90, pp. 92-95, 2012, ISSN: 0167-9317, (Micro&Nano 2010).
Resumen | Enlaces | BibTeX | Etiquetas: Diamond, Nanowires, Phonons, Raman scattering, Tight-binding
@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}
}
A local bond-polarization model based on the displacement–displacement 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.
2008
Alfaro, Pedro; Cruz, Miguel; Wang, Chumin
Vibrational states in low-dimensional structures: An application to silicon quantum wires Artículo de revista
En: Microelectronics Journal, vol. 39, no 3, pp. 472-474, 2008, ISSN: 1879-2391, (The Sixth International Conference on Low Dimensional Structures and Devices).
Resumen | Enlaces | BibTeX | Etiquetas: Phonons, Raman scattering, Silicon nanowires
@article{ALFARO2008472,
title = {Vibrational states in low-dimensional structures: An application to silicon quantum wires},
author = {Pedro Alfaro and Miguel Cruz and Chumin Wang},
url = {https://www.sciencedirect.com/science/article/pii/S0026269207001711},
doi = {https://doi.org/10.1016/j.mejo.2007.07.082},
issn = {1879-2391},
year = {2008},
date = {2008-01-01},
urldate = {2008-01-01},
journal = {Microelectronics Journal},
volume = {39},
number = {3},
pages = {472-474},
abstract = {The Raman scattering in Si nanowires is studied by means of the local bond-polarization model based on the displacement\textendashdisplacement Green\'s function within the linear response theory. In this study, the Born potential, including central and non-central interatomic forces, and a supercell model are used. The results show a notable shift of the main Raman peak towards lower energies, in comparison with the bulk crystalline Si case. This shift is compared with the experimental data and discussed within the quantum confinement framework.},
note = {The Sixth International Conference on Low Dimensional Structures and Devices},
keywords = {Phonons, Raman scattering, Silicon nanowires},
pubstate = {published},
tppubtype = {article}
}
The Raman scattering in Si nanowires is studied by means of the local bond-polarization model based on the displacement–displacement Green's function within the linear response theory. In this study, the Born potential, including central and non-central interatomic forces, and a supercell model are used. The results show a notable shift of the main Raman peak towards lower energies, in comparison with the bulk crystalline Si case. This shift is compared with the experimental data and discussed within the quantum confinement framework.
