[1] Seoul Natl Univ, Inst Basic Sci, Ctr Nanoparticle Res, Seoul 151744, South Korea
[2] Seoul Natl Univ, Dept Elect & Comp Engn, Seoul 151744, South Korea
[3] Seoul Natl Univ, Interuniv Semicond Res Ctr, Seoul 151744, South Korea
[4] Seoul Natl Univ, Interdisciplinary Program Bioengn, Seoul 151744, South Korea