arXiv subjects

R. Gómez

Publications and source records attributed to R. Gómez.

5 recordsLinked to original sources

arXiv2025

InN nanowire solar cells on Si with amorphous Si interlayer deposited by sputtering

Here, we report the first experimental demonstration of InN nanowire solar cells deposited by RF sputtering with a bandgap energy of 1.78 eV. By adding an amorphous Si (a-Si) buffer to the n-InN/p-Si structure, we have improved the photovoltaic performance of the resulting devices while maintaining their material quality. We have firstly optimized the deposition of Si on Si(100) by DC sputtering, obtaining an amorphous material with bandgap energy of 1.39 eV. Then we have studied the influence of the thickness of the a-Si buffer layer (0-25 nm) on the structural, morphological, electrical, and optical properties of InN nanowires on Si (100) substrates. With the use of a 15-nm buffer, n-InN/a-Si/p-Si nanowire heterojunction solar cells exhibit a promising short-circuit current density of 17 mA/cm2, open circuit voltage of 0.37 V and fill factor of 35.5%, pointing to a power-conversion efficiency of 2.3% under 1-sun (AM 1.5G) illumination. These work demonstrated that the combination of in-situ sputtered a-Si, which could serve as potential passivation layer, and the light trapping enhancement by the nanostructured active layer leads to an improvement of the photovoltaic efficiency of sputtered III-nitride devices.

physics.app-ph↗

arXiv2025

Extremal Problems on Forest Cuts and Acyclic Neighborhoods in Sparse Graphs

Chernyshev, Rauch, and Rautenbach proved that every connected graph on $n$ vertices with less than $\frac{11}{5}n-\frac{18}{5}$ edges has a vertex cut that induces a forest, and conjectured that the same remains true if the graph has less than $3n-6$ edges. We improve their result by proving that every connected graph on $n$ vertices with less than $\frac{9}{4}n$ edges has a vertex cut that induces a forest. We also study weaker versions of the problem that might lead to an improvement on the bound obtained.

math.CO↗

arXiv2016

A Study of Shell Model Neutron States in $^{207,209}Pb$ Using the Generalized Woods-Saxon plus Spin-Orbit Potential

The experimental binding energies of single-particle and single-hole neutron states belonging to neutron shells that extend from N = 126 to 184 and 82 to 126 respectively, have been reproduced by solving the Schrödinger equation with a potential that has two components: the generalized Woods-Saxon (GWS) potential and the spin-orbit (SO) coupling term. The GWS potential contains the traditional WS potential plus a term (SU) whose intensity reaches a maximum in the nuclear surface. Our results indicate the existence of a explicit relationship between the strength of the SU potential and the orbital angular momentum quantum number $\ell$ of the state. This dependence has been used to make reasonable predictions for the excitation energy centroids of states located inside and outside the neutron shells investigated. Comparisons are made with results reported in previous investigations.

nucl-th↗

arXiv2015

Quantum Discord of $f$-Deformed Bipartite Entangled Oscillators

Quantum correlations in compound systems are of great importance, and they are fundamental resource for the development of quantum computation protocols and quantum information. In this work we construct bipartite pure coherent states using the $f$-deformed oscillator formalism and the Barut-Girardello deformation function. Also we construct the extension of these systems to mixed states using Werner like states. For the states constructed, we study the dependence of the entanglement and quantum discord upon the deformation and mixed parameters.

quant-ph↗

arXiv2011

Algorithm to compute the electric field gradient tensor in ionic crystals

A simple algorithm and a computational program to numerically compute the electric field gradient and the concomitant quadrupolar nuclear splitting is developed for an arbitrary ionic crystal. The calculations are performed using a point charge model. The program provides three different ways for the data input: by Bravais lattices, by lattice parameters, or by introducing any spatial structure. The program calculates the components of the electric field gradient, the asymmetry parameter and the quadrupolar splitting for a given number of nearest neighbors with respect to the nuclear charge as origin. In addition, the program allows the use of different Sternheimer antishielding factors.

cond-mat.mtrl-sci↗