6533b824fe1ef96bd1280940

RESEARCH PRODUCT

Comparative Theoretical Analysis of BN Nanotubes Doped with Al, P, Ga, As, In, and Sb

subject

description

SUMMARY AND CONCLUDING REMARKS We have performed large-scale first-principles calculations ofthe electronic structure of (5,5) boron nitride nanotubescontaining the following substitutional impurity atoms: Al, P,Ga, As, In, and Sb. Calculations have been performed using thetwo methods: (i) linear combination of atomic orbitals(LCAO) with the atomic-centered Gaussian-type functions asa basis set and (ii) linearized augmented cylindrical wave(LACW) accompanied with the local density functional andmuffin-tin approximations for the electronic potential. In arelatively good qualitative agreement, both methods predict lowformation energies and, thus, relative stability of point defectsthat are associated with the atom substitutions in the BN NTwalls. Along with this, the formation energies of a singlesubstitutional point defect onto relaxed BN NT have beenfound increased along with increased atomic mass of thesubstitutional defect. Analysis of equilibrium distances betweenthe substitutional defect and nanotube’s host atoms demon-strates that their bond lengths tend to be elongated with respectto B−N bond length of pristine BN NT. Such a relaxation isaccompanied with slightly increased covalency along with extracharge redistribution between the defect and the nanotube. Thecalculated density of states shows the formation of midgapstates in the band gap of BN NT, thus leading to the narrowingof a gap. On the basis of our quantum-chemical calculations,we, therefore, conclude that the presence of isoelectronicimpurities significantly affects the band structure of BNnanotubes, which must be taken into account whenconstructing nanoelectronic devices based on these nanotubes.We assume that all the mentioned effects can be observed byboth optical and photoelectron spectroscopy methods, as wellas by measuring the electrochemical properties of BN NTs.