Epitaxial Growth and Composition-Dependent Optical Properties of Vertically Aligned ZnS1-xSex Alloy Nanowire Arrays

Vertically aligned ZnS1-xSex alloy nanowire arrays covering the entire compositional range were grown on GaAs (111)B substrates by metal organic chemical vapor deposition (MOCVD) using Ga nanoparticles as catalysts. The ZnS1-xSex nanowires obtained are predominantly zincblende in structure and preferentially grow along the [111] direction. They show a narrow distribution in composition, which is the result of good growth controls afforded by MOCVD. The relationship between composition of the nanowires and the precursors was studied and determined; it allows the predetermination of the composition of the alloy nanowires. In low temperature (77 K) cathodoluminescence spectra, the band edge emission of ZnS1-xSex nanowires is found to shift from 3.214 to 2.779 eV, and its line width significantly decreases from 213 to 44 meV, when the Se content increases From 0.45 to 1. This phenomenon is understood in terms of the chemical disorder in the alloy.