چكيده به لاتين
In order to develop electronic devices with a better performance, and with the aim of minimizing these components, we are looking for materials with extraordinary features with better efficiency. Since its discovery, graphene as a two dimensional form of carbon has attracted a lot of attention due to its outstanding electrical, mechanical, thermal characteristics. But its gapless nature limits its potential applications in nanoelectronics. Hence, considering ways to overcome this limitation is important. For this purpose, we have manipulated electron transport in graphene-based structures in various methods.
The electrical conductance of zigzag graphene nanoribbons (ZGNRs) in the presence of different percentages of edge and middle vacancies is numerically investigated by using the recursive Green's function method. The calculations show that increasing the both vacancy types in the system exponentially reduces the conductance. At fixed defect concentration, the length growth leads to exponential decrease, and the width growth leads to power law increase in the conductance of ZGNRs, respectively. Then we have investigated the electron transport in bilayer ZGNR by changing interlayer spacing in two inline and perpendicular directions taking advantage of non-equilibrium Green's function method. The results show that by growing the inline gap between two layers the conductance behavior changes from oscillatory to dipping. Also, changing the distance in a vertical direction alone does not have much effect on the bilayer conductance.
We have also checked the transport in graphene/hexagonal boron-nitride (hBN) lateral hybrid structures with doped rhombus and bowtie domains, by using non-equilibrium Green's function method based on tight binding model under nearest neighbor approximation. Our findings confirmed that the presence of hBN domains could have a positive effect on the transport depending on the doped regions shape. Increasing the percentage of hBN, due to its semiconducting nature, leads to a reduction in conduction. Furthermore, dopping h-BN with carbon atoms can improve the electronic transport of this semiconducting structure. At the end, we dope boron and nitrogen in ZGNR, with different arrangements and calculate the conductance based on the density functional theory with the help of the SIESTA package. The calculations show that the arrangement of boron and nitrogen atoms can affect the electronic behavior of the mentioned hybrid structure.
