The Mechanism of Ni-Assisted GaN Nanowire Growth

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• 作者：Carina B. Maliakkal ; Nirupam Hatui ; Rudheer D. Bapat ; Bhagyashree A. Chalke ; A. Azizur Rahman ; Arnab Bhattacharya
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：December 14, 2016
• 年：2016
• 卷：16
• 期：12
• 页码：7632-7638
• 全文大小：429K
• ISSN：1530-6992

文摘

Despite the numerous reports on the metal-catalyzed growth of GaN nanowires, the mechanism of growth is not well understood. Our study of the nickel-assisted growth of GaN nanowires using metalorganic chemical vapor deposition provides key insights into this process. From a comprehensive study of over 130 nanowires, we observe that as a function of thickness, the length of the nanowires initially increases and then decreases. We attribute this to an interplay between the Gibbs–Thomson effect dominant in very thin nanowires and a diffusion induced growth mode at larger thickness. We also investigate the alloy composition of the Ni–Ga catalyst particle for over 60 nanowires using energy dispersive X-ray spectroscopy, which along with data from electron energy loss spectroscopy and high resolution transmission electron microscopy suggests the composition to be Ni<sub>2sub>Ga<sub>3sub>. At the nanowire growth temperature, this alloy cannot be a liquid, even taking into account melting point depression in nanoparticles. We hence conclude that Ni-assisted GaN nanowire growth proceeds via a vapor–solid–solid mechanism instead of the conventional vapor–liquid–solid mechanism.