S3 Center, Nanoscience Institute - CNR, Via Campi 213/a, 41125 Modena, Italy.
S3 Center, Nanoscience Institute - CNR, Via Campi 213/a, 41125 Modena, Italy ; FIM Department, University of Modena and Reggio Emilia, Via Campi 213/a, 41125 Modena, Italy.
Beilstein J Nanotechnol. 2015 Jun 11;6:1298-305. doi: 10.3762/bjnano.6.134. eCollection 2015.
Suspended nanowires (SNWs) have been deposited from Co-carbonyl precursor (Co2(CO)8) by focused electron beam induced deposition (FEBID). The SNWs dimensions are about 30-50 nm in diameter and 600-850 nm in length. The as-deposited material has a nanogranular structure of mixed face-centered cubic (FCC) and hexagonal close-packed (HCP) Co phases, and a composition of 80 atom % Co, 15 atom % O and 5 atom % C, as revealed by transmission electron microscopy (TEM) analysis and by energy-dispersive X-ray (EDX) spectroscopy, respectively. Current (I)-voltage (V) measurements with current densities up to 10(7) A/cm(2) determine different structural transitions in the SNWs, depending on the I-V history. A single measurement with a sudden current burst leads to a polycrystalline FCC Co structure extended over the whole wire. Repeated measurements at increasing currents produce wires with a split structure: one half is polycrystalline FCC Co and the other half is graphitized C. The breakdown current density is found at 2.1 × 10(7) A/cm(2). The role played by resistive heating and electromigration in these transitions is discussed.
采用聚焦电子束诱导沉积（FEBID）技术，从 Co-羰基前体（Co2(CO)8）中沉积出悬浮纳米线（SNWs）。SNWs 的直径约为 30-50nm，长度为 600-850nm。透射电子显微镜（TEM）分析和能谱（EDX）分析分别显示，沉积材料具有混合面心立方（FCC）和六方密排（HCP）Co 相的纳米颗粒结构，组成分别为 80 原子%Co、15 原子%O 和 5 原子%C。高达 10^7 A/cm^2 的电流（I）-电压（V）测量确定了 SNWs 中的不同结构转变，这取决于 I-V 历史。单次测量中突然的电流爆发会导致整个纳米线扩展为多晶 FCC Co 结构。在增加电流的重复测量中，产生了具有分裂结构的纳米线：一半是多晶 FCC Co，另一半是石墨化的 C。击穿电流密度为 2.1×10^7 A/cm^2。讨论了电阻加热和电迁移在这些转变中所起的作用。
