Papers by Keyword: Tersoff Potential

Abstract: Silicon-graphene nanoribbon (SiGNR), an allotrope of silicon carbide with sp² hybridization, gains interest nowadays in the world of two-dimensional materials. In this study, the thermal conductivity of SiGNR is investigated and compared to that of graphene nanoribbon (GNR) and silicene nanoribbon (SiNR). Molecular Dynamics using Tersoff potential through Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) using the Green-Kubo method is employed to predict the thermal conductivity of silicon-graphene materials with armchair chirality. The temperature is varied from 50 K, 77 K, 150 K, 300 K, 500 K, 700 K, 1000 K, 1200 K, and 1500 K with a fixed width of 10 nm and length of 50 nm. The length of the materials is also varied from 10 nm, 20 nm, 30 nm, 40 nm and 50 nm with a fixed temperature of 300 K. Our results show that the thermal conductivity of SiGNR is higher than that of GNR and is approximately 50% larger at room temperature, which may be attributed to the presence of Si atoms inducing larger flexural phonon density of states than in GNR and SiNR. Also, the thermal conductivity of SiGNR follows the same length-dependent behavior of GNR due to its long mean free path. This study presents new insights into the thermal properties of silicon-graphene which will be significant for nanoelectronic applications.

Abstract: Based on the assumption that sp3 hybridization is more stable in bulk silicon, this study is a step forward in understanding the structures and mechanical properties of silicon nanotubes (SiNT). Using the well tested form of Tersoff potential we have calculated cohesive energy and other parameters for SiNT of various diameters and chiralities. Using this potential, the results obtained for bulk silicon are satisfactory, so we expect that the same potential would work well with SiNT as well. We calculated Young’ modulus and shear modulus for SiNT. Young’s modulus lies in the range of 100- 200 GPa which is about 10-20 times lower than CNT and shear modulus lies between 200-300 GPa. This work shall motivate further theoretical and experimental work in the field of nanostructures.

Abstract: The diamond structure of single crystal silicon transforms to other structures under mechanical stress. We investigate the structural transformation of diamond cubic structure to betatin structure in silicon
under uniaxial stress using atomistic simulation on the basis of the Tersoff potential. As a result, under extensive compressive strain, the structural transformation from Si-I to Si-II is found.

Abstract: Developments of tetrahedral amorphous carbon (ta-C) films having low residual compressive stress are essential to extend the applicability of the films. The annealing of the ta-C films was known to be an effective way for the reduction the stress of the films. However, the effects of annealing on the atomic structure of ta-C films have not been fully understood. The atomic structure changes by the annealing were studied using molecular dynamics simulation. The simulation showed that the annealing caused an increase of the atomic volume of ta-C film, which explained the stress reduction partially. However, the tendency of the stress reduction was different to high and low stress films. The annealing substantially reduced the stresses of high stress films compared to those of low stress films. Atomic structure analysis showed that the reason for the asymmetric stress reduction resulted from the relaxation of highly distorted bonds that existed in as-deposited films.

Abstract: We have investigated the single-wall boron-, aluminum- and gallium-nitride nanotubes using atomistic simulations based on the Tersoff potential. The Tersoff potential for III-nitride effectively describes the properties of III-nitride nanotubes. Structures, energetic and nanomechanics of III-nitride nanotubes were investigated and compared with each other. Young’s moduli of III-N nanotubes were lower than that of CNT. Though the graphite-like sheet formation of AlN was very difficult, since the elastic energy per atom to curve the sheet into cylinder for AlN was very low, if graphite-like sheets of AlN were formed, the extra cost to produce the tubes would be very low