Focused Electron Beam Deposition of Nanowires from Cobalt Tricarbonyl Nitrosyl (Co(CO)3NO) Precursor

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• 作者：Gian Carlo Gazzadi ; Hans Mulders ; Piet Trompenaars ; Alberto Ghirri ; Marco Affronte ; Vincenzo Grillo ; Stefano Frabboni
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：October 13, 2011
• 年：2011
• 卷：115
• 期：40
• 页码：19606-19611
• 全文大小：992K
• 年卷期：v.115,no.40(October 13, 2011)
• ISSN：1932-7455

文摘

Nanowires deposited by focused electron beam-induced deposition (FEBID) of cobalt tricarbonyl nitrosyl (Co(CO)₃NO) precursor have been thoroughly characterized from an electrical, magnetic, and structural point of view. Deposit composition and deposition yield have been studied as a function of beam energy and current. Atomic concentrations are weakly dependent on beam parameters and have average values of 49 at % for Co, 27 at % for O, 14 at % for N, and 10 at % for C. Deposition yield decreases as the beam energy increases, and strong enhancement (67脳) is observed for deposition at 130 掳C substrate temperature. FEBID nanowires are highly resistive (蟻 = 6.3 m惟 cm at RT), and resistivity increases as T decreases with a power-law behavior typical of metal鈥搃nsulator (M鈥揑) nanogranular systems. Nonmagnetic behavior is revealed by magnetoresistance (MR) measurements. After 400 掳C vacuum annealing, conductivity of the nanowire is greatly improved (蟻 = 62 渭惟 cm at RT), and a metallic-like resistivity is fully recovered. MR angular plots display a (cos 胃)² dependence typical of anisotropic MR (AMR) in ferromagnets, with AMR values of 0.85%. Co concentration in the deposit is not significantly increased though. TEM structural analysis reveals that before annealing the deposit has a CoO fcc structural phase with nanograins size around 1 nm. After annealing, a new Co hcp phase shows up beside CoO fcc, and coarsening (10 鈥?15 nm) and interconnection of the Co nanograins are observed, providing the conditions for ferromagnetism and metallic electrical transport.