Growth of ordered arrangements of one-dimensional germanium nanostructures with controllable crystallinities

Channelled templates such as anodic alumina membranes (AAMs) can be utilized to host, isolate, and guide the growth of one-dimensional (1D) nanostructures. In this study, we present a method for Au-seeded and confined growth of 1D Ge nanostructures with controlled crystallinities and electrical properties within the channels of AAMs. Our approach combines Au nanoparticle seeded growth of semiconductor nanowires by supercritical fluid-liquid-solid (SFLS) mechanism and the highly anisotropic structure of the aligned channels in AAMs. Au seeds with nanosized dimensions were prepositioned inside channelled substrates, followed by SFLS growth at temperatures slightly higher than the Au/Ge eutectic point. Microscopy and XRD measurements reveal that the 1D nanostructures can be obtained with tuneable and controllable crystallinity, grain size and domain boundaries, ranging from chains of Au-nanoparticles connected through semiconductor Ge nanocrystallities, to Au-seeded Ge single crystalline nanowires. Conditions that control the type of Ge nanostructures are (i) the distribution and size of the Au seeds across the alumina surfaces, (ii) the type of SCF deposition, e.g., batch versus flow-through deposition. Additionally, we present electrical data of the ordered arrays of ID nanostructures, measured by conductive atomic force microscopy (c-AFM), and contrast the data to that previously obtained for similar systems.