MicroelectronicsR&DCentre;
InstituteofSemiconductors;
ChineseAcademyofSciences;
Beijing100083//DepartmentofPhysics;
JinanUniversity;
Jinan250022;
MicroelectronicsR&DCentre;
InstituteofSemiconductors;
ChineseAcademyofSciences;
Beijing100083;
InstituteofMicrosystemandInformationTechnology;
ChineseAcademyofSciences;
Shanghai200050;