LAUSR

Semiconductor nanowires offer the opportunity to incorporate novel structures and functionality into electronic and optoelectronic devices. A clear understanding of the nanowire growth mechanism is essential for well-controlled growth of structures with desired properties, but the understanding is currently limited by a lack of empirical measurements of important parameters during growth, such as catalyst particle composition. However, this is difficult to accurately determine by investigating post-growth. We report direct in situ measurement of the catalyst composition during nanowire growth for the first time. We study Au-seeded GaAs nanowires inside an electron microscope as they grow and measure the catalyst composition using X-ray energy dispersive spectroscopy. The Ga content in the catalyst during growth increases with both temperature and Ga precursor flux. Semiconductor nanowires are promising materials for miniaturized devices, but a thorough understanding of their growth mechanism is necessary for controlled synthesis. Here, the authors use in situ spectroscopy and microscopy to measure the composition of the catalyst droplet as a function of different growth parameters during Au-seeded GaAs nanowire growth.