Tuning the electronic structures of semiconducting SiC nanotubes by N and NHx (x=1,2) groups.

We investigate the stable configurations and electronic structures of silicon carbide nanotubes (SiCNTs) decorated by N and NH_x (x=1,2) groups by using first-principles calculations. We find that these groups can be chemically incorporated into the network of SiCNTs in different ways, accompanied with the formation of N–C and N–Si bonds. The adsorbing energy of N and NH_x (x=1,2) groups on (5,5) and (8,0) SiCNTs ranges from -1.82 to -7.19 eV. The electronic structures of SiCNTs can be effectively modified by these groups and display diverse characters ranging from semiconducting to semimetallic, depending on the chirality of SiCNTs as well as the way of the incorporation of these functional groups. The relationship between the electronic structures and the configurations of these functionalized SiCNTs is also addressed by performing projected density of states combined with Milliken population analysis. These results are expected to open a way to tune the electronic structures of SiCNTs which may have promising applications in building nanodevices. [ABSTRACT FROM AUTHOR]