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By using the first-principles calculation methods, the stable structures of oxygen incorporated [formula] surface of AlN and InN are explored in comparison with that of GaN. The one for AlN is found to be VAl-(ON)3, a complex of Al vacancy and three substitutional O in N sites, while the one for InN is consistent with that of GaN, which is comprised by two monolayers of O replacing the N atoms, denoted by 2(ON). The stabilization mechanisms of the two surface structures and the origin of the discrepancy between AlN and GaN are further given by analyzing their electronic structures. [ABSTRACT FROM AUTHOR]

Using first-principles methods, we investigated the atomic relaxations, electronic structure, and formation energies of nonpassivated AlN nanowires along [0001] directions. We find that all the nanowires prefer to have [formula] lateral facets and all the wires with [formula] lateral facets are semiconductors with a direct band gap. However, surface states that arise from the facet atoms exist inside the bulklike band gap, which can have a large effect on the optoelectronic properties of the nanowires. Our calculated formation energies of the nanowires show that there is a sublinear relationship between the formation energy and surface-to-volume ratio, indicating that the surface effect is localized and becomes more important for small nanowires. [ABSTRACT FROM AUTHOR]

Abstract: Porous AlN particles were prepared from an aluminum–magnesium melt solution. These samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and N2-adsorption isotherms. The results show that there are many pore formations in every AlN particle, and the wall thickness of the pores is about 10 nm, the diameter of the pores is hundreds of nanometers and the Brunauer–Emmett–Teller (BET) surface area of the samples is 65.183 m2/g. [Copyright &y& Elsevier]