Submitted on: 13 July 2013.
Revised on: 06 August 2013.
Accepted on: 30 August 2013.
Optoelectronics and Advanced Materials-Rapid Communications
http://reply.papertrans.cn/3/238/23746/23746-32.png
http://reply.papertrans.cn/3/238/23746/23746-33.png
Submitted on: 23 June 2015.
Revised on: 07 July 2015.
Accepted on: 14 July 2015.
Optoelectronics and Advanced Materials-Rapid Communications
http://reply.papertrans.cn/3/238/23746/23746-35.png
http://reply.papertrans.cn/3/238/23746/23746-36.png