^pof;
Optoclcctronic;
Information,;
State;
Key;
Laboratory;
of;
Electronic;
Thin;
Films;
and;
Integrated;
Devices,;
University;
of;
Electronic;
Science;
and;
Technology;
of;
China;
(UESTC),;
Chengdu,;
610054,;
China;
^pand;
Physical;
Science;
College,;
Sichuan;
Agricultural;
University,;
Ya'an;
625014,;
China;