Investigation of the factors influencing nanostructure array growth by PLD towards reproducible wafer‐scale growth

Abstract

The growth of catalyst‐free ZnO nanostructure arrays on silicon (111) substrates by pulsed laser deposition was investigated. Without an underlayer, randomly oriented, micron‐scale structures were obtained. Introduction of a c‐axis oriented ZnO underlayer resulted in denser arrays of vertically oriented nanostructures with either tapering, vertical‐walled or broadening forms, depending on background Ar pressure. Nanostructure pitch seemed to be determined by underlayer grain size while nanostructure widths could be narrowed from ∼100–500 to ∼10–50 nm by a 50 °C increase in growth temperature. A dimpled underlayer topography correlated with the moth‐eye type arrays while a more granular surface was linked to vertically walled nanocolumns. Between‐wafer reproducibility was demonstrated for both moth‐eye and vertical nanocolumn arrays. Broadening nanostructures proved difficult to replicate, however. Full 2 inch wafer coverage was obtained by rastering the target with the laser beam.