Epitaxial Growth of GaAs Nanowires on Synthetic Mica by Metal-Organic Chemical Vapor Deposition.

The epitaxial growth of III-V nanowires with excellent optoelectronic properties on low-cost, light-weight, and flexible substrates is a key step for the design and engineering of future optoelectronic devices. In our study, GaAs nanowires were grown on synthetic mica, a two-dimensional layered material, via vapor-liquid-solid growth using metal-organic chemical vapor deposition. The effect of basic epitaxial growth parameters such as temperature and V/III ratio on the vertical yield of the nanowires is investigated. A vertical yield of over 60% is achieved at an optimum growth temperature of 400 °C and a V/III ratio 18. The structural properties of the nanowires are investigated using various techniques including scanning electron microscopy, high-resolution transmission electron microscopy, and high-angle annular dark-field imaging. The vertical nanowires grown at a low temperature and a high V/III ratio are found to have a zincblende phase with a [111] B polarity. The optical properties are investigated by photoluminescence (PL) and time-resolved PL measurements. First-principles electronic structure calculations within the framework of density functional theory elucidate the van der Waals nature of the nanowire/mica interface. Our results also show that these nanowires can be easily lifted off the bulk 2D mica template, providing a pathway for flexible nanowire devices.