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22 pages, 512 KiB

Open AccessArticle

Impact of B and P Doping on the Elastic Properties of Si Nanowires

by Nedhal Ali Mahmood Al-Nuaimi, Angela Thränhardt and Sibylle Gemming

Nanomaterials 2025, 15(3), 191; https://doi.org/10.3390/nano15030191 - 25 Jan 2025

Cited by 1 | Viewed by 1037

Using gradient-corrected density functional theory we investigate the mechanical properties of ultrathin boron (B) and phosphorus (P) doped silicon nanowires (SiNWs) along the [001] and [111] orientations within the PBE approximation. Both pristine and doped SiNWs under study have diameters ranging from 5 [...] Read more.

B_{0}

), shear modulus (

G_{V}

), Young’s modulus (Y), and other mechanical parameters. The significant anisotropy observed in the mechanical properties of Si[111] NWs, with varying moduli along different axes, further illustrates the complex interplay between mechanical behavior and electronic structure at the nanoscale. The mechanical flexibility of SiNWs, combined with their tunable electronic properties due to quantum confinement, makes them promising candidates for advanced nanoelectronic devices, nanoelectromechanical systems (NEMS), and advanced technologies. Full article

(This article belongs to the Special Issue Semiconductor Nanowires and Devices)

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14 pages, 1125 KiB

Open AccessArticle

Density Functional Investigation of [001] and [111] SiNWs and the Effect of Doping with Boron and Phosphorus

by Nedhal Ali Mahmood Al-Nuaimi, Florian Hilser and Sibylle Gemming

Crystals 2024, 14(7), 585; https://doi.org/10.3390/cryst14070585 - 25 Jun 2024

Cited by 2 | Viewed by 1412

Abstract

In the present study, we investigate the influence of boron (B) and phosphorus (P) (p- and n-type, respectively) doping on the electronic properties of ultra-thin silicon nanowires (SiNWs) by gradient-corrected density functional calculations with the Perdew–Burke–Ernzerhof (PBE) approximation. In the limit of very small diameters (5–8 Å), both pristine and highly active unsaturated SiNWs with orientations along the [001] and [111] directions exhibit electronic states around the Fermi level, indicative of conductive properties. Conduction is further enhanced by the introduction of doping atoms, as demonstrated by the relative change in the band structures of SiNWs with and without B and P doping. This investigation provides an important insight into the electronic states of SiNWs, which are candidates for future electronics or sensing applications. Full article

(This article belongs to the Special Issue Advanced Research in Semiconductor Materials and Devices)

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26 pages, 449 KiB

Open AccessReview

Revisiting the COVID-19 Pandemic: An Insight into Long-Term Post-COVID Complications and Repurposing of Drugs

by Rajib Majumder, Sanmitra Ghosh, Manoj K. Singh, Arpita Das, Swagata Roy Chowdhury, Abinit Saha and Rudra P. Saha

COVID 2023, 3(4), 494-519; https://doi.org/10.3390/covid3040037 - 6 Apr 2023

Cited by 3 | Viewed by 6797

Abstract

SARS-CoV-2 is a highly contagious and dangerous coronavirus that has been spreading around the world since late December 2019. Severe COVID-19 has been observed to induce severe damage to the alveoli, and the slow loss of lung function led to the deaths of many patients. Scientists from all over the world are now saying that SARS-CoV-2 can spread through the air, which is a very frightening prospect for humans. Many scientists thought that this virus would evolve during the first wave of the pandemic and that the second wave of reinfection with the coronavirus would also be very dangerous. In late 2020 and early 2021, researchers found different genetic versions of the SARS-CoV-2 virus in many places around the world. Patients with different types of viruses had different symptoms. It is now evident from numerous case studies that many COVID-19 patients who are released from nursing homes or hospitals are more prone to developing multi-organ dysfunction than the general population. Understanding the pathophysiology of COVID-19 and its impact on various organ systems is crucial for developing effective treatment strategies and managing long-term health consequences. The case studies highlighted in this review provide valuable insights into the ongoing health concerns of individuals affected by COVID-19. Full article

12 pages, 2393 KiB

Open AccessArticle

Formation and Performance of Diamond (111)/Cu Interface from First-Principles Calculation

by Yongsheng Zhao, Fengyun Yan and Yi An

Coatings 2022, 12(5), 619; https://doi.org/10.3390/coatings12050619 - 2 May 2022

Cited by 11 | Viewed by 3303

Abstract

The interface formation and properties of composite materials are very important for the preparation of composite materials, and the bonding state and charge transfer between atoms in the interface have a particularly significant effect on the interface formation. In this work, the first-principles calculation method was used to study the adsorption behavior and molecular dynamics of copper atoms on the (111) surface of H-terminated diamond, and the adsorption energy and adhesion work of Cu atoms were calculated. The results show that the adsorption of copper atoms is not sensitive to the diamond (111) surface, the adsorption work is very small at the four high symmetry positions, and the adhesion work is the largest at the T4 position and is 0.6106 J/m². Furthermore, according to the electron localization function (ELF) analysis, there is no compound formation between Cu and H atoms; only a small amount of charge transfer exists, which belongs to physical adsorption. The diamond–copper interface formed by the growth of adsorption sites is a metastable structure without energy stability. This work provides an important theoretical reference for understanding the formation mechanism of copper-based diamond composites. Full article

(This article belongs to the Topic Materials and Surface Treatment Processes Used for Engineering Applications)

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23 pages, 3872 KiB

Open AccessArticle

Cu-Doped KCl Unfolded Band Structure and Optical Properties Studied by DFT Calculations

by César Castillo-Quevedo, Jose Luis Cabellos, Raul Aceves, Roberto Núñez-González and Alvaro Posada-Amarillas

Materials 2020, 13(19), 4300; https://doi.org/10.3390/ma13194300 - 26 Sep 2020

Cited by 1 | Viewed by 3623

Abstract

The unfolded band structure and optical properties of Cu-doped KCl crystals were computed by first principles within the framework of density functional theory, implemented in the ABINIT software program, utilizing pseudopotential approximation and a plane-wave basis set. From a theoretical point of view, Cu substitution into pristine KCl crystals requires calculation by the supercell (SC) method. This procedure shrinks the Brillouin zone, resulting in a folded band structure that is difficult to interpret. To solve this problem and gain insight into the effect of copper ions (Cu⁺) on electronic properties, the band structure of SC KCl:Cu was unfolded to make a direct comparison with the band structure of the primitive cell (PC) of pristine KCl. To understand the effect of Cu substitution on optical absorption, we calculated the imaginary part of the dielectric function of KCl:Cu through a sum-over-states formalism and broke it down into different band contributions by partially making an iterated cumulative sum (ICS) of selected valence and conduction bands. Consequently, we identified those interband transitions that give rise to the absorption peaks due to the Cu⁺ ion. These transitions involve valence and conduction bands formed by the Cu-3d and Cu-4s electronic states. Full article

(This article belongs to the Section Materials Physics)

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9 pages, 1368 KiB

Open AccessArticle

Nitrogen Trapping Ability of Hydrogen-Induced Vacancy and the Effect on the Formation of AlN in Aluminum

by Duy Dat Vo, Aleksey G. Lipnitskii, Truong Khang Nguyen and Thoi Trung Nguyen

Coatings 2017, 7(6), 79; https://doi.org/10.3390/coatings7060079 - 9 Jun 2017

Cited by 4 | Viewed by 5462

Abstract

This paper presents the ternary interaction of N, H, and vacancy point defects and the nitrogen trapping ability of aluminum vacancies induced by hydrogen by means of DFT methods employed in VASP (Vienna Ab initio Simulation Package) and Abinit packages. The obtained vacancy formation energy of 0.65 eV is close to experimental values. Although the N–vacancy complex is unstable with the negative binding energy of −0.51 eV, the stability of H–vacancy–N is proved by the positive binding energy of 0.59 eV and the appearance of the orbital hybridization in the density of state (DOS) of atoms connecting to this complex. Moreover, Al vacancies can trap more than 4 N atoms, which prevents the formation of aluminum nitride and subsequently affects not only the hardness of the Al surface but also many practical applications of AlN coating. Full article

(This article belongs to the Special Issue Modelling and Simulation of Coating)

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