Ab-initio study of structural, elastic and electronic properties of core/shell nanowires

ABSTRACT This Zinc oxide (ZnO) is widely used in different electronic devices due to its thermal, electronic, and piro-piezoelectric properties. Some of these properties are noticeable improvement at the nanoscale, specially when ZnO together with other material create heterostructures. Recently, core/shell nanowires have been synthesized in order to raise the performance in devices like piezo-electronic sensors, photovoltaic cells, and optoelectronic devices. In this work, we introduce a theoretical study of structural, elastic and electronic properties of core/shell nanostructures of ZnO/X (X=ZnS, BeO) when they are subjected to uniaxial stresses in the [0001] direction. Hexagonal nanowires, whose diameters range from 1.5 to 2.8 nm, were ab-initio studied using the density functional theory, in the generalized gradient approximation (GGA), implemented in the SIESTA code. By applying uniaxial stresses, we calculated the Young modulus, maximum tensile, and both total (TDOS) and projected electronic density of states (PDOS). We have observed a degradation in the mechanical properties of core/shell nanowires with respect to ZnO nanowires. Depending on the external shells (BeO or ZnS), the core/shell nanowires became more insulator or more semiconductor. These results are important in nano electronic devices based on ZnO, in order to tailor their optoelectronic properties.