High Curie Temperature Achieved in the Ferromagnetic Mn<sub>x</sub>Ge<sub>1−x</sub>/Si Quantum Dots Grown by Ion Beam Co-Sputtering
Xiaoxiao Duan,
Shuming Ye,
Jing Yang,
Chen Li,
Chunjiang Lu,
Xinpeng He,
Luran Zhang,
Rongfei Wang,
Feng Qiu,
Jie Yang,
Haoyang Cui,
Chong Wang
Affiliations
Xiaoxiao Duan
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Shuming Ye
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Jing Yang
Key Lab of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, China
Chen Li
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Chunjiang Lu
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Xinpeng He
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Luran Zhang
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Rongfei Wang
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Feng Qiu
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Jie Yang
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Haoyang Cui
College of Electronic and Information Engineering, Shanghai University of Electric Power, Shanghai 200090, China
Chong Wang
National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China
Ferromagnetic semiconductors (FMSs) exhibit great potential in spintronic applications. It is believed that a revolution of microelectronic techniques can take off, once the challenges of FMSs in both the room-temperature stability of the ferromagnetic phase and the compatibility with Si-based technology are overcome. In this article, the MnxGe1−x/Si quantum dots (QDs) with the Curie temperature (TC) higher than the room temperature were grown by ion beam co-sputtering (IBCS). With the Mn doping level increasing, the ripening growth of MnGe QDs occurs due to self-assembly via the Stranski–Krastanov (SK) growth mode. The surface-enhanced Raman scattering effect of Mn sites observed in MnGe QDs are used to reveal the distribution behavior of Mn atoms in QDs and the Si buffer layer. The Curie temperature of MnxGe1−x QDs increases, then slightly decreases with increasing the Mn doping level, and reaches its maximum value of 321 K at the doping level of 0.068. After a low-temperature and short-time annealing, the TC value of Mn0.068Ge0.932 QDs increases from 321 K to 383 K. The higher Ge composition and residual strain in the IBCS grown MnxGe1−x QDs are proposed to be responsible for maintaining the ferromagnetic phase above room temperature.
