arXiv subjects

G. A. Mantashian

Publications and source records attributed to G. A. Mantashian.

3 recordsLinked to original sources

arXiv2026

Charge Transport Modeling of CdSe/ZnS core/shell Quantum Nanorod Light-Emitting Diodes

In this study, we investigate the electronic structure, charge transport dynamics, and optical properties of a quantum dot light-emitting diode (QD-LED) featuring a double nanorod (NR) emission layer composed of CdSe-ZnS core-shell structures. Utilizing a rigorous self-consistent numerical approach, we solve the coupled Schrodinger-Poisson equations iteratively to obtain accurate wave functions, energy levels, and potential profiles under varying external bias voltages. Detailed analyses reveal voltage-dependent electron localization dynamics, demonstrating a systematic transition of electrons between distinct NR regions via quantum tunneling. Charge density and electrostatic potential distributions are modeled comprehensively, employing the asymmetric Erlang distribution to characterize interface effects. By calculating current-voltage (I-V) characteristics and photoluminescence spectra, we demonstrate that external voltage serves as a robust tuning parameter for modulating emission energies and intensities, underscoring the potential of these NR-LED systems for tunable optoelectronic and photonic applications.

cond-mat.mes-hall↗

arXiv2025

Voxel-scale quantum state control in nanorod ensembles using reconfigurable needle beams

Precisely addressing single nanostructures inside dense ensembles remains a bottleneck for scalable photonic and quantum information devices. Here we demonstrate, through comprehensive finite element and variational Monte-Carlo modelling, that a reconfigurable three-dimensional array of needle shaped beams can selectively switch the quantum optical response of individual InAs nanorods embedded in GaAs. By tuning the local non resonant intensity pattern the exciton and biexciton energies were calculated, electromagnetically induced transparency (EIT) windows were examined, and correspondingly near-field diffraction carpets were dynamically reshaped. A single parameter the activation ratio between illuminated and dark nanorods provides continuous control over photoluminescence peak position (80 meV) and EIT bandwidth (six times). We further predict fully programmable Talbot self-imaging in nanorod arrays with sub-wavelength pitch. Importantly, the observed Talbot carpets enable spatially resolved identification of which nanorods were excited, offering a powerful diagnostic for verifying structured-light activation schemes. The concept offers a low crosstalk, wafer scale route toward reconfigurable quantum emitters, tunable diffractive optics and on-chip slow-light components.

physics.optics↗

arXiv2022

Modelling of Quantum Dots with the Finite Element Method

Considering the increasing number of experimental results in the manufacturing process of quantum dots with different geometries, and the fact that most numerical methods that can be used to investigate quantum dots with non-trivial geometries require large computational capacities the finite element method becomes an incredibly attractive tool for modeling semiconductor QDs. In the current article, the authors have used the FEM to obtain the first twenty-six probability densities and energy values for the following GaAs structures: rectangular, spherical, cylindrical, ellipsoidal, spheroidal, and conical QDs, quantum rings, nanotadpoles, and nanostars. The results of the numerical calculations were compared with the exact analytical solutions and a good deviation was obtained. The ground states energies dependence on the element size was obtained to find the optimal parameter for the investigated structures. The abovementioned calculation results were used to obtain valuable insight into the effects of the size quantization s dependence on the shape of the QDs. Additionally, the wavefunctions and energies of spherical CdSe/CdS quantum dots were obtained while taking into account the diffusion effects on the potential depth with the use of a piecewise Woods-Saxon potential. The diffusion of the effective mass and the dielectric permittivity is obtained with the use of a normal Woods-Saxon potential. A structure with a quasi-type-II band alignment was obtained at the core size of 2.2nm. This result is consistent with the experimental data.

cond-mat.mtrl-sci↗