[1] Solid-State Electronics Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, United States
[2] MS 177, One AMD Place, Sunnyvale, CA 94088-3453, United States
[3] Department of Electronic Device Engineering, Graduate School of Information Science and Electrical Engineering, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan