[1] Samsung Elect, Samsung Adv Inst Technol, Frontier Res Lab, Gyeonggi Do 446712, South Korea
[2] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA
[3] Myongji Univ, Dept Phys, Yongin 449728, South Korea
[4] Myongji Univ, Dept Nano Sci & Engn, Yongin 449728, South Korea
[5] Korea Elect Technol Inst, Energy Nanomat Res Ctr, Songnam 463816, Gyeonggi Do, South Korea