부산대학교 도서관

The effect of concentration and position of boron atoms as impurities in graphene nanoribbons have been studied through density functional theory (DFT) and the Landauer approach. For this purpose, we designed a graphene nanoribbon doped with three different concentrations of boron atoms and calculated the density of states (DOS), electronic current, and thermopower. The comparison between the DOS curve of the pure graphene and that of the boron-doped graphene shows that the presence of boron atoms as impurities in graphene has caused an energy gap near the Fermi energy. Moreover, the study of the I-Vcharacteristics shows that not only the current quantization is established, but also the reduction in conductivity caused by doping with boron atoms can be observed; however, this reduction is not sensitive to the concentration of boron atoms. In addition, the changes of the Seebeck coefficient shows that in both pure and boron-doped graphene, the curve has a minimum value at the temperature of 10 K, which decreases to a lower value by increasing the concentration of boron atoms. Generally, the result of calculations shows that by increasing the boron concentration, not only the energy gap of graphene is changed, but also several changes appear in its thermoelectric properties that can be attributed to the impurity potential distribution. The results of this study can be effectively used for designing semiconductor electronic devices based on the graphene nanoribbon. Key words: B-doped graphene, DFT, Landauer approach, thermoelectric, electronic. Nous utilisons la theorie de la fonctionnelle de densite et l'approche de Landauer pour etudier les effets de la concentration et de la position des atomes de bore comme impuretes dans des nanorubans de graphene. A cette fin nous presentons des nanorubans de graphenes dopes avec trois differentes concentrations d'atomes de bore et nous calculons la densite d'etats (DdE/DOS), le courant electronique et le coefficient de Seebeck. La comparaison des courbes DdE des nanorubans non dopes avec ceux dopes montre que la presence des atomes de bore cause l'apparition d'un gap en energie pres de l'energie de Fermi. Aussi, l'etude des caracteristiques I-V montre que non seulement la quantification du courant est verifiee et qu'on peut aussi observer une reduction de la conductivite par le dopage au bore, mais que cette reduction n'est pas sensible a l'augmentation de la concentration en bore. De plus, les changements du coefficient de Seebeck montrent que dans les deux cas, dope et non dope, la courbe a une valeur minimale a 10K, qui diminue avec l'augmentation de la concentration en bore. De fa^on generale, les resultats de nos calculs montrent que l'augmentation de la concentration de bore, non seulement change le gap en energie du graphene, mais aussi les proprietes thermoelectriques, attribuable a la distribution des impuretes. Les resultats de cette etude peuvent etre utilises dans le design de composants electroniques semiconducteurs construits sur la base de nanorubans de graphene. [Traduit par la Redaction] Mots-cles: graphene dope au B, theorie de la fonctionnelle de densite ou TFD, approche de Landauer, thermoelectrique, electronique.
Introduction Graphene, as a single layer of carbon atoms with [sp.sup.2] hybridization, has recently attracted the attention of researchers due to its unique structure and properties [1,2]. Graphene has no [...]