Synthesis and alignment of Zn and ZnO nanoparticles by laser-assisted chemical vapor deposition.

ABSTRACT

A simple, versatile, and fast laser-assisted chemical vapor deposition (LCVD) technique that produces linear arrays of Zn and ZnO nanoparticles on a silicon substrate, covering an extended region, is described. A series of consecutive steps is involved in the synthesis and alignment of Zn/ZnO nanoparticles. First, a Lloyd's mirror arrangement is employed to produce two types of periodic nanostructure, i.e., nanoripples and nanoprotrusions. Next, the nanostructured substrate is laser irradiated at a fluence of 60 mJ cm(-2) in the presence of the metall-organic (MO) precursor gas diethylzinc (DEZn). The evolution of the Zn nanocrystals by LCVD processing was studied as a function of precursor gas pressure and laser fluence by ex situ high-resolution scanning electron microscopy (SEM). Laser irradiation fulfills a double role it decomposes the adsorbed precursor and causes the evolution of resulting Zn into aligned aggregates of zinc nanoparticles. The Zn nanoparticles react with oxygen upon high-temperature thermal annealing to yield aligned assemblies of ZnO nanoparticles. The production of ZnO was confirmed by x-ray diffraction (XRD) and photoluminescence spectra. This technique is general and could be used in a large number of substrate/precursor combinations.