S.H. Moustafa

Bio: S.H. Moustafa is an academic researcher from Helwan University. The author has contributed to research in topics: Thin film & Band gap. The author has an hindex of 8, co-authored 25 publications receiving 179 citations.

DC electrical properties of amorphous carbon with different bonding hybridization

Abstract: Temperature dependence of dc conductivity in hydrogenated amorphous carbon (a-C:H) samples, deposited in the range of −200 to −700 V self-bias voltages, was studied above room temperature from 300 K to 650 K. Because a non-Arrhenius dependence on 1/T was found, actual activation energy Eact was determined by derivation of the log σ versus T−1. This Eact increased gradually with temperature by a rate depending on self bias. Strong fluctuations of Eact, observed above 500 K, indicates a transition to another conduction mechanism. Below 500 K the plot of log σ versus T−1/4 could be fitted to linear functions, with an unrealistic density of states at Fermi energy, supporting, that underlying mechanism cannot be variable range hopping near EF rather it is related to conduction by hopping of carriers excited to band tails.

Materials Science Forum

Abstract: Properties and Application of Geopolymers Vol. 841 (/MSF.841 /book) Development and Investigation of Materials Using Modern Techniques Vol. 840 (/MSF.840/book) Superplasticity in Advanced Materials ICSAM 2015 Vols. 838-839 (/MSF.838-839/book) 12th International Conference on High Speed Machining Vols. 836-837 (/MSF.836-837/book) Sintering Fundamentals II Vol. 835 (/MSF.835/book) Advanced Machining Technologies: Traditions and Innovations Vol. 834 (/MSF.834/book) Applied Materials and Technologies Vol. 833 (/MSF.833/book) Emerging Functional Materials: Book (/MSF.841/book) Papers (/MSF.841)

Electron and Phonon Properties of Graphene: Their Relationship with Carbon Nanotubes

Abstract: The discovery of Novoselov et al. (2004) of a simple method to transfer a singleatomic layer of carbon from the c-face of graphite to a substrate suitable for themeasurement of its electrical and optical properties has led to a renewed interest inwhat was considered to be before that time a prototypical, yet theoretical,two-dimensional system. Indeed, recent theoretical studies of graphene reveal that thelinear electronic band dispersion near the Brillouin zone corners gives rise to electronsand holes that propagate as if they were massless fermions and anomalous quantumtransport was experimentally observed. Recent calculations and experimentaldetermination of the optical phonons of graphene reveal Kohn anomaliesat high-symmetry points in the Brillouin zone. They also show that theBorn–Oppenheimer principle breaks down for doped graphene. Since a carbonnanotube can be viewed as a rolled-up sheet of graphene, these recent theoretical andexperimental results on graphene should be important to researchers working oncarbon nanotubes. The goal of this contribution is to review the exciting newsabout the electronic and phonon states of graphene and to suggest howthese discoveries help understand the properties of carbon nanotubes.

Fabrication and Size-Dependent Optical Properties of FeO Nanoparticles Induced by Laser Ablation in a Liquid Medium

Abstract: We report the fabrication of FeO nanoparticles by pulse laser ablation of pure iron plate in the poly(vinylpyrrolidone) solutions. It has been found that the particle size can be controlled in a wide range from 45 to 5 nm by the surfactant concentration from 0.01 to 0.2 M. The optical absorption measurements of the obtained colloidal solutions show that the optical absorption edge red shifts with reduction of the particle size and exhibits the optical features of the semiconductor with indirect band gap. The red shift is attributed to lattice defects in the nanoparticles. This study shows that pulse laser ablation in liquid media is a good method to synthesize some nanoparticles with special structures, which are difficult to produce by other conventional methods.