Effects Of The Defect And Dopant On In Adsorption On Graphene

Graphene is a new carbon-based material being first made successfully in laboratory in 2004. Due to the excellent electronics properties and the environmental stabilibty, graphene was viewed as the best candidate for making the nanoscale translateors and then developing the CMOS chip. In this paper, the author studies the structure and the electronic properties of In(Indium) adsorption on graphene and the structural properties of In quantum line on graphene using the first-principles method. The relation of adsorption energy vs coverage was discussed. Furthermore, the effects of vacancy and Si dopant on In adsorption on graphene was investigated in detail.First, we adopt the VASP, which based on Density functional theory (DFT), to optimalize the structure of monolayer graphene and get the value of lattice parameter a=2.466 ?, which is in better agreement with the experimental value. The different adsorption structure of In on graphene and the relation of adsorption energy versus coverage are studied. It is indicated that the structure of the quantum line of In on graphene is more stable, the interaction between In-In adatoms in the line is strengthened, however, the interaction between In adatoms of different lines is weak. For the higher of adsorption height, the interaction between In adatoms and graphene is not strong, the adsorption height and the adsorption energy of In on graphene at the different adsorption site differs very small. Comparing with the adsorption system of In-graphene at the coverage of 1/6 ML(monolayer) with the model of 3×3 , the interaction between In adatoms of the latter models is smaller and that between In adatoms and graphene is greater, and so the difference for the different adsorption site is greater. But the best adsorption site for both models is same, at Top site, and accordingly the adsorption energy differs pretty small.Next, in order to understanding the adsorption behavior of In on graphene deeply, we study the effects of vacancy and Si-dopant on In adsorption on graphenen. Is is shown that the vacancy strengthens the adsorption of In on graphene, which makes the In adsorption on graphene stabler for low coverage (e.g. 1/32ML). It attributes to that vacancy provides the more dangling bonds which makes the interaction between In and graphene stronger in the case of the main interaction is between In adatoms and graphene for low coverage. In the calculations we use a Si atom replacing a C atom in graphene to form a model of Si doping. Si doping strengths the In adsorption on graphene, especially, for highe coverage (e.g. 1/3 ML). In the case of higher coverage the In adsorption height is higher and the interaction between In and graphene is weaker. Si-dopant which replaced a C atom in graphene stands out the graphene a certain height to In adsorption direction, which provides a media between In adatoms and graphene. So the Si dopant makes the weak interaction between In and graphene stronger, comparing with In-graphene system without Si-dopant, the In adsorption becomes stabler.