title: First-principles calculations of AlN nanowires and nanotubes: atomic structures, energetics, and surface states.
abstract: We explore the atomic and electronic structures of single-crystalline aluminum nitride nanowires (AlNNWs) and thick-walled aluminum nitride nanotubes (AlNNTs) with the diameters ranging from 0.7 to 2.2 nm by using first-principles calculations and molecular dynamics simulations based on density functional theory (DFT). We find that the preferable lateral facets of AlNNWs and thick-walled AlNNTs are {1010} surfaces, giving rise to hexagonal cross sections. Quite different from the cylindrical network of hexagons revealed in single-walled AlNNTs, the wall of thick-walled AlNNTs displays a wurtzite structure. The strain energies per atom in AlNNWs are proportional to the inverse of the wire diameter, whereas those in thick-walled AlNNTs are independent of tube diameter but proportional to the inverse of the wall thickness. Thick-walled AlNNTs are energetically comparable to AlNNWs of similar diameter, and both of them are energetically more favorable than single-walled AlNNTs. Both AlNNWs and AlNNTs are wide band gap semiconductors accompanied with surface states located in the band gap of bulk wurtzite AlN.
authors.affiliation: School of Physics and Microelectronics, School of Electric Engineering, Shandong University, Jinan 250100, China. zmw@sdu.edu.cn
authors.forename: Mingwen
authors.initials: M
authors.lastname: Zhao
authors.forename: Yueyuan
authors.initials: Y
authors.lastname: Xia
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Liu
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Tan
authors.forename: Boda
authors.initials: B
authors.lastname: Huang
authors.forename: Chen
authors.initials: C
authors.lastname: Song
authors.forename: Liangmo
authors.initials: L
authors.lastname: Mei