1. Institute
of Microelectronics, Tsinghua University, Beijing, China 100084
2. Tsinghua National Laboratory for Information Science and Technology (TNList), Beijing, China, 100084
3. Institute
of Microelectronics, Chinese Academy of Sciences, Haidian District, Beijing, China 100029
4. Shenyang
National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China, 110016