[1] Chonbuk Natl Univ, Semicond Phys Res Ctr, Sch Semicond & Chem Engn, Jeonju 561756, South Korea
[2] Korea Elect Power Res Inst, Power Integr Grp, Taejon 305380, South Korea
[3] Korea Basic Sci Inst, Jeonju Ctr, Jeonju 561756, South Korea
[4] Elect & Telecommun Res Inst, Future Technol Res Grp, Taejon 305700, South Korea
[5] Sri Venkateswara Univ, Dept Phys, Tirupati 517502, Andhra Pradesh, India