Departamento de Física, Universidade Federal Rural de Pernambuco, Recife, Brazil.
Nanotechnology. 2010 Sep 17;21(37):375401. doi: 10.1088/0957-4484/21/37/375401. Epub 2010 Aug 19.
Spin polarization is a key characteristic in developing spintronic devices. Diluted magnetic heterostructures (DMH), where subsequent layers of conventional and diluted magnetic semiconductors (DMS) are alternate, are one of the possible ways to obtain it. Si being the basis of modern electronics, Si or other group-IV DMH can be used to build spintronic devices directly integrated with conventional ones. In this work we study the physical properties and the spin-polarization effects of p-type DMH based in group-IV semiconductors (Si, Ge, SiGe, and SiC), by performing self-consistent [Formula: see text] calculations in the local spin density approximation. We show that high spin polarization can be maintained in these structures below certain values of the carrier concentrations. Full spin polarization is attained in the low carrier concentration regime for carrier concentrations in the DMS layer up to approximately 2.0 x 10(19) cm(-3) for Si and up to approximately 6.0 x 10(19) cm(-3) for SiC. Partial, but still important spin polarization can be achieved for all studied group-IV DMH, with the exception of Ge for carrier concentrations up to 6.0 x 10(19) cm(-3). The role played by the effective masses and the energy splitting of the spin-orbit split-off hole bands is also discussed throughout the paper.
自旋极化是发展自旋电子器件的关键特性。稀释磁性异质结构（DMH），其中后续层的常规和稀释磁性半导体（DMS）交替，是获得自旋极化的可能方法之一。硅是现代电子学的基础，因此硅或其他 IV 族 DMH 可用于构建直接与传统器件集成的自旋电子器件。在这项工作中，我们通过在局域自旋密度近似下进行自洽[公式：见文本]计算，研究了基于 IV 族半导体（硅、锗、硅锗和碳化硅）的 p 型 DMH 的物理性质和自旋极化效应。我们表明，在一定的载流子浓度下，这些结构可以保持较高的自旋极化。对于 DMS 层中的载流子浓度高达约 2.0×10(19)cm(-3)的硅和约 6.0×10(19)cm(-3)的碳化硅，在低载流子浓度范围内可以实现完全自旋极化。对于所有研究的 IV 族 DMH，除了载流子浓度高达 6.0×10(19)cm(-3)的锗之外，都可以实现部分但仍然重要的自旋极化。本文还讨论了有效质量和自旋轨道分裂空穴带的能量分裂在自旋极化中的作用。
