Continuous gas-phase synthesis of nanowires with tunable properties

Abstract

Semiconductor nanowires are key building blocks for the next generation of light-emitting diodes, solar cells and batteries. To fabricate functional nanowire-based devices on an industrial scale requires an efficient methodology that enables the mass production of nanowires with perfect crystallinity, reproducible and controlled dimensions and material composition, and low cost. So far there have been no reports of reliable methods that can satisfy all of these requirements. Here we show how aerotaxy, an aerosol-based growth method, can be used to grow nanowires continuously with controlled nanoscale dimensions, a high degree of crystallinity and at a remarkable growth rate. In our aerotaxy approach, catalytic size-selected Au aerosol particles induce nucleation and growth of GaAs nanowires with a growth rate of about 1 micrometre per second, which is 20 to 1,000 times higher than previously reported for traditional, substrate-based growth of nanowires made of group III-V materials. We demonstrate that the method allows sensitive and reproducible control of the nanowire dimensions and shape--and, thus, controlled optical and electronic properties--through the variation of growth temperature, time and Au particle size. Photoluminescence measurements reveal that even as-grown nanowires have good optical properties and excellent spectral uniformity. Detailed transmission electron microscopy investigations show that our aerotaxy-grown nanowires form along one of the four equivalent〈111〉B crystallographic directions in the zincblende unit cell, which is also the preferred growth direction for III-V nanowires seeded by Au particles on a single-crystal substrate. The reported continuous and potentially high-throughput method can be expected substantially to reduce the cost of producing high-quality nanowires and may enable the low-cost fabrication of nanowire-based devices on an industrial scale.

Scalable and Environmentally Benign Process for Smart Textile Nanofinishing

“…Here, we propose a sustainable and universal approach to textile nanofinishing that relies on a single-step NP synthesis and deposition process. Among the various aerosol processes, electrical discharges allow the high-yield synthesis of a wide range of well-defined NPs [20][21][22][23][24][25] (with respect to NP concentration, size, 26,27 crystallinity, 28 and chemical composition 29,30 ) that can be directly deposited onto textile fibers by diffusion, in a green and universal manner. The uniqueness of the proposed process lies in that diffusional deposition can be easily integrated into textile nanofinishing while providing a controlled loading profile within the textiles.…”

Semiconductor nanowires: a platform for exploring limits and concepts for nano-enabled solar cells

“…In addition, NW design 96 and synthesis efforts should minimize NW heterogeneity with regards to size and doping, because variations in these parameters can limit the power conversion efficiency of the system 97 . Finally, although the total systems cost of an assembled NW photovoltaic is difficult to quantify rigorously, synthetic advances including nanowire growth by aerotaxy 98 , use of cheaper metal catalysts and lower temperature processes 52 will likely be a primary driver of cost reductions. Ultimately, the assembly and large-scale integration of diverse NW building blocks could become a viable strategy for development of efficient and costeffective solar cells.…”

Nano-objects emitted during maintenance of common particle generators: direct chemical characterization with aerosol mass spectrometry and implications for risk assessments

“…In most cases a sintering process gives near spherical particles but can in some cases lead to hexagonal or cubic like shapes. Applications of sintered metal particles, synthesized with the described generator system, includes for instance nanowire production in the gas-phase using aerotaxy (Heurlin et al 2012). A DMA is included in the system downstream the sintering furnace.…”