چكيده به لاتين
Carbon was one of the first elements known to humans and is the material prima for life and the basis of all organic chemistry. Because of the flexibility of its bonding, Carbon-based systems show an unlimited number of different structure with an equally large variety of physical properties, these physical properties are, in great part, the result of the dimensionality of these structures. Among systems with only Carbon atoms, Graphene a two dimensional (2D) allotrope of Carbon plays an important role since it is the basis for the understanding of the electronic properties in other allotropes. Graphene is made out of carbon atoms arranged on a honeycomb structure made out of hexagons. Fullerenes are molecules where Carbon atoms are arranged spherically, and hence, from the physical point of view, are zero-dimensional objects with discrete energy states. Fullerenes can be thought of as wrapped-up Graphene. Carbon nanotubes are obtained by rolling Graphene along a given direction and reconnecting the Carbon bonds and can be thought of as one dimensional (1D) objects. Diamond and Graphite are both three dimensional (3D) crystalline forms of the element carbon. The discovery of Graphene took 60 years to go from controversial predictions to successful cleavage of Graphene from graphite. Finally, in 2004, researchers at the University of Manchester, led by Game and Novoslov, succeeded in producing Graphene in a laboratory. Graphene is the first truly two-dimensional crystal sample, containing only one layer of carbon atoms. That Graphene is a gapless semiconductor with unique electronic properties, the charge carriers in graphene obey a linear dispersion relation. so in the case of graphene energy is directly proportional to momentum, which implies that the charge carriers in the graphene have zero effective mass. and the quasi-particles in graphene obey from Dirac equation. Massless Dirac’s fermions can penetrate wide, long electrostatic barriers with a high probability transmission. This study shows that massless Dirac’s fermions can be transmitted through barriers with probability 1. The behavior of the transmission probability through a barrier depends incident angle is examined.
