School;
of;
Physics;
and;
Microelectronics,;
Shandong;
University,;
Jinan;
250100,;
China;
School;
of;
Physics;
and;
Microelectronics,;
Shandong;
University,;
Jinan;
250100,;
China;
School;
of;
Physics;
and;
Microelectronics,;
Shandong;
University,;
Jinan;
250100,;
China;
School;
of;
Physics;
and;
Microelectronics,;
Shandong;
University,;
Jinan;
250100,;
China;
Institute;
of;
Semiconductor,;
Shandong;
Normal;
University,;
Jinan;
250014,;
P.R.;
China;
Institute;
of;
Semiconductor,;
Shandong;
Normal;
University,;
Jinan;
250014,;
P.R.;
China;