Local Current Distribution in a Ferromagnetic Tunnel Junction Fabricated Using Microwave Excited Plasma Method
Local Current Distribution in a Ferromagnetic Tunnel Junction Fabricated Using Microwave Excited Plasma Method
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微波激发等离子体法制造的铁磁隧道结中的局部电流分布
DOI：
10.4283/jkms.2003.13.2.047
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发表时间：
2003
影响因子：
4.5
通讯作者：
Ying Li
中科院分区：
文献类型：
--
作者：
T. Yoon;Cheolgi Kim;Chong‐Oh Kim;M. Tsunoda;M. Takahashi;Ying Li
采用直流磁控溅射和等离子体氧化工艺制备铁磁隧道结。使用接触模式原子力显微镜（AFM）和局部电流-电压分析研究了铁磁隧道结的局部输运特性。在热氧化硅片上制备了 sub./Ta/Cu/Ta/NiFe/Cu/Mn75/Ir25//Co70/Fe30//Al-氧化物结构的隧道结。使用径向线缝隙天线（RLSA）用微波激发等离子体形成Al-氧化物层5秒和7秒。使用Kr气体作为与用于等离子体氧化的气体混合的惰性气体。当同时测量时，未观察到形貌和当前图像之间的相关性。局部电流分布与局部势垒高度的分布很好地识别。假设局部势垒高度呈高斯分布，氧化时间较长的铁磁隧道结与实验结果很好地吻合。相反，在较短时间的氧化结的情况下，由于氧不足，电流主要流经低势垒高度区域。这种漏电流可能会导致隧道磁阻（TMR）比降低。
Ferromagnetic tunnel junctions were fabricated by dc magnetron sputtering and plasma oxidation process. The local transport properties of the ferromagnetic tunnel junctions were studied using contact-mode Atomic Force Microscopy (AFM) and the local current-voltage analysis. Tunnel junctions with the structure of sub./Ta/Cu/Ta/NiFe/Cu/Mn75/Ir25//Co70/Fe30//Al-oxide were prepared on thermally oxidized Si wafers. Al-oxide layers were formed with microwave excited plasma using radial line slot antenna (RLSA) for 5 and 7 sec. Kr gas was used as the inert gas mixed with gas for the plasma oxidization. No correlation between topography and current image was observed while they were measured simultaneously. The local current distribution was well identified with the distribution of local barrier height. Assuming the gaussian distribution of the local barrier height, the ferromagnetic tunnel junction with longer oxidation time was well fitted with the experimental results. As contrast, in the case of the shorter time oxidation junction, the current mainly flow through the low barrier height area for its insufficient oxygen. Such leakage current might result in the decrease of tunnel magnetoresistance (TMR) ratio.