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Phosphorus and aluminum -doped boron nitride nanotube geometry and electrical properties of theoretical research

Author: YeZuo
Tutor: SunMiao
School: Harbin University of Science and Technology
Course: Chemical processes
Keywords: Boron nitride nanotubes P and Al -doped Density functional theory Formation energy Band
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 24
Quote: 0
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Abstract


Boron nitride nanotube is an electronic nature relatively stable, single , wide band gap semiconductor materials. It is a large band gap (4.5 ~ 5.5eV), but its diameter is almost , chiral , helicity , the wall structure , layers independent of the parameters , so that it is poor conductive properties , almost exhibit the characteristics of an insulator . Boron nitride nanotubes based on its inherent limitations, can be changed by doping hetero atom , and their geometries to achieve the desired electronic properties of the material. In this paper, the content of impurities such as electron atom phosphorus (P) and aluminum (Al) doping concentration and doping location of the boron nitride nanotube geometry and electrical properties . Based on this, we selected single-walled armchair ideal for single-cycle and three cycles of boron nitride nanotubes and doping P, Al boron nitride nanotube system, using first-principles density functional theory calculations of the bond lengths of all system , bond angles , doping system, the formation energy, electronic band structure and the electronic density of states . Here we use the Material Studio software to build molecular models and use them Castep module calculates the geometric structure and electrical properties . The results show that the geometry of various doping system were changed, symmetry reduced. With the formation of impurities to the increase of the impurity concentration , the incorporation of P atom than the corresponding formation energy of incorporation of Al atoms to form much larger ; Although the two different positions of doping atoms of the formation energy little difference, but more than any one single atom doping should be much greater. Three-cycle system, the band gap will be doped with the impurity atom concentration decreases , but the two positions of the doped band gap difference in the size is small. Single-cycle system of doping system in the valence band of the conduction band between the top and bottom will introduce 2n (n = impurity atoms ) of energy levels . The total density of states of various systems almost always come from the contribution of the electron orbit p , s orbit electron contribution is small , and for boron nitride nanotubes doped system, near the Fermi level of the contribution of the density of states are p impurity atoms from the electron orbit . Can be drawn from the results P atoms and Al atoms replace atoms incorporated into the form of boron nitride nanotubes , which greatly changes its electrical properties , it has a conductor or semiconductor characteristics.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
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