arXiv subjects

M. L. Benkhedir

Publications and source records attributed to M. L. Benkhedir.

4 recordsLinked to original sources

arXiv2026

First-principles study of the impact of As doping on the structural and electronic properties of MoS$_2$ monolayer

This study is aimed at exploring the structural and electronic properties of doped MoS$_2$ monolayers, including Mo and S vacancies and As doped systems, employing DFT calculations. The electronic properties were analyzed to understand how these modifications affect the behavior of the material. Introduction of defects generates new defect states in the midgap. In the S-vacancy (V$_\text{S}$), Mo-vacancy (V$_{\text{Mo}}$), As-Mo (As substituting Mo), and As-S (As substituting S) doped systems, the downward shift of the Fermi level to the valence band indicates a $p$-type behavior. In the As interstitial system the Fermi level shifts to the conduction band, suggesting an $n$-type semiconductor. The results highlight that doping MoS$_2$ with As, particularly at the Mo site, can be used in photocatalysis and high-efficiency photovoltaics. Additionally, the As interstitial system demonstrates an enhanced performance in field-effect transistors (FETs).

cond-mat.mtrl-sci↗

arXiv2025

Investigation of density of states and charge carrier mobility in amorphous semiconductors via time-of-flight photocurrent analysis

The present study examines the electronic transport characteristics of amorphous semiconductors through TOF measurements and numerical simulations. The primary objective is to determine the DOS in amorphous selenium (a-Se) and to assess the temperature and electric field dependence of the hole mobility. A comprehensive investigation of localized states within the mobility gap is performed using Laplace transform analysis of ToF photocurrent transients, combined with the multiple trapping model. This approach enables accurate reconstruction of the DOS across a wide temperature range, allowing clear identification of shallow and deep trap levels and revealing thermally activated transport mechanisms. Simulated ToF currents are also used to evaluate the hole drift mobility under various thermal and field conditions. Activation energies are extracted from Arrhenius plots of the mobility data. The results support a physically consistent description of the electronic structure in a-Se and validate the applicability of Laplace-based techniques for probing charge transport in disordered semiconductors.

cond-mat.mtrl-sci↗

arXiv2024

Effect of arsenic doping on structural and electronic properties of MoSe$_2$ monolayer: an ab initio study

In this paper, we studied the structural and electronic properties of MoSe$_2$ monolayer in its pure and doped forms, using the density functional theory (DFT), and the calculations were performed using Quantum Espresso (QE) software package. The doped systems are a MoSe$_2$ monolayer with a vacancy in Mo site (Mo vacancy system), the MoSe$_2$ monolayer with an As atom as substitutional for Mo atom (As(Mo) doped system) and an MoSe$_2$ monolayer with As atom in an interstitial site in the hollow location of the center of one ring of the structure between the plane Mo atoms and the plane containing Se atoms (As interstitial system). We calculated the formation energy of various structures studied in Se-rich condition. We found that the As(Mo) doped system is a favorable configuration, whereas the As interstitial system is metastable. Different defects introduce midgap levels, which were interpreted according to the orbitals involved in their formation using the analysis of the band structure and DOS and PDOS of each system. The energy gap increases in all system structures and its value ranged between 1.5 eV and 1.73 eV, the Fermi level shifts toward the valence band for the Mo vacancy system, and As(Mo) doped system which suggests that it can be a $p$-type semiconductor, whereas Fermi level shifts to the conduction band for As interstitial system and suggests a $n$-type semiconductor behavior. The obtained results enable us to predict the possibility of using these systems in many applications, since it can be used in the As(Mo) doped system in photocatalysis or in photovoltaic applications in the visible light, and As interstitial system can be used in electronics applications in the infrared field.

cond-mat.mtrl-sci↗

arXiv2006

Charge Transport Properties of a Metal-free Phthalocyanine Discotic Liquid Crystal

Discotic liquid crystals can self-align to form one-dimensional semiconducting wires, many tens of microns long. In this letter, we describe the preparation of semiconducting films where the stacking direction of the disc-like molecules is perpendicular to the substrate surface. We present measurements of the charge carrier mobility, applying temperature-dependent time-of-flight transient photoconductivity, space-charge limited current measurements, and field-effect mobility measurements. We provide experimental verification of the highly anisotropic nature of semiconducting films of discotic liquid crystals, with charge carrier mobilities of up to 2.8x10$^{-3}$cm$^2$/Vs. These properties make discotics an interesting choice for applications such as organic photovoltaics.

cond-mat.mtrl-sci↗