Electrical spin injection in p-type Si using Fe/MgO contacts
Electrical spin injection in p-type Si using Fe/MgO contacts
复制标题
使用 Fe/MgO 接触在 p 型 Si 中进行电自旋注入
DOI：
10.1117/12.930839
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
K. Ando
中科院分区：
文献类型：
--
作者：
A. Spiesser;S. Sharma;H. Saito;R. Jansen;S. Yuasa;K. Ando
本文报道了利用外延的MgO(001)隧道势垒和Fe(001)电极在室温下成功地在p型硅中产生自旋极化。反射高能电子衍射观察表明，在(2×1)重构的Si表面上可以生长出外延的Fe/MgO(001)隧道接触，而在(1×1)Si表面上生长的隧道接触是多晶的。透射电子显微镜图像显示，与多晶结构相比，外延Fe/MgO/Si具有更平坦的界面。对于Fe/MgO/p-Si器件，利用三端子组态在300K观察到明显的Hanle效应和倒置Hanle效应，证明在室温下可以在Si中诱导自旋极化。由Hanle曲线的宽度推算出的有效自旋寿命分别为95±6ps和143±10ps。观察到的差异可以定性地解释为多晶样品界面粗糙度较大时产生的局部磁场。具有外延Fe/MgO隧道接触的样品表现出较高的自旋累积量，其自旋累积量与偏置极性几乎对称，而多晶MgO样品的自旋累积量表现出非常不对称的演化。这可能归因于作为自旋过滤器的外延Fe/MgO(001)隧道接触具有较高的自旋极化程度。我们的实验结果表明，外延氧化镁势垒有利于在硅中产生自旋。
We report the successful electrical creation of spin polarization in p-type Si at room temperature by using an epitaxial MgO(001) tunnel barrier and Fe(001) electrode. Reflection high-energy electron diffraction observations revealed that epitaxial Fe/MgO(001) tunnel contacts can be grown on a (2×1) reconstructed Si surface whereas tunnel contacts grown on the (1×1) Si surface were polycrystalline. Transmission electron microscopy images showed a more flat interface for the epitaxial Fe/MgO/Si compared to that of the polycrystalline structure. For the Fe/MgO/p-Si devices, the Hanle and inverted Hanle effects were clearly observed at 300 K by using a three-terminal configuration, proving that spin polarization can be induced in the Si at room temperature. Effective spin lifetimes deduced from the width of the Hanle curve were 95 ± 6 ps and 143 ± 10 ps for the samples with polycrystalline and epitaxial MgO tunnel contacts, respectively. The observed difference can be qualitatively explained by the local magnetic field induced by the larger roughness of the interface of the polycrystalline sample. The sample with epitaxial Fe/MgO tunnel contact showed higher magnitude of the spin accumulation with a nearly symmetric behavior with respect to the bias polarity whereas that of the polycrystalline MgO sample exhibited a quite asymmetric evolution. This might be attributed to the higher degree of spin polarization of the epitaxial Fe/MgO(001) tunnel contact, which acts as a spin filter. Our experimental results suggest that an epitaxial MgO barrier is beneficial for creating spins in Si.