Wang Liming, Zhang Yichi, Liu Tao, Zhang Zhi, Hu Huiyong, Zou Jin, Jia Quanjie, Jiang Zuimin
State Key Discipline Laboratory of Wide Bandgap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, China.
State Key Laboratory of Surface Physics, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
Nanoscale. 2020 Feb 14;12(6):3997-4004. doi: 10.1039/c9nr09315j. Epub 2020 Feb 4.
Self-assembled MnGe quantum dots (QDs) on a Si substrate or GeSi virtual substrate (VS) were grown by molecular beam epitaxy. The GeSi VS of different thicknesses and Ge compositions x were utilized to modulate the ferromagnetic properties of the above QDs. The MnGe QDs on GeSi VS show a significantly enhanced ferromagnetism with a Curie temperature above 220 K. On the basis of the microstructural and magnetization results, the ferromagnetic properties of the QDs on GeSi VS are believed to come from the intrinsic MnGe ferromagnetic phase rather than any intermetallic ferromagnetic compounds of Mn and Ge. At the same time, we found that by increasing the Ge composition x of GeSi VS, the ferromagnetism of QDs grown on VS will markedly increase due to the improvements of hole concentration and Ge composition inside the QDs. These results are fundamentally important in the understanding and especially in the realization of high Curie temperature MnGe diluted magnetic semiconductors.
通过分子束外延生长在硅衬底或锗硅虚拟衬底（VS）上的自组装锰锗量子点（QDs）。利用不同厚度和锗成分x的锗硅VS来调节上述量子点的铁磁性能。锗硅VS上的锰锗量子点表现出显著增强的铁磁性，居里温度高于220K。基于微观结构和磁化结果，认为锗硅VS上量子点的铁磁性能来自本征锰锗铁磁相，而非锰和锗的任何金属间铁磁化合物。同时，我们发现通过增加锗硅VS的锗成分x，由于量子点内部空穴浓度和锗成分的改善，生长在VS上的量子点的铁磁性将显著增加。这些结果对于理解尤其是实现高居里温度的锰锗稀磁半导体具有根本重要性。
