1. Department of Electrical Engineering, Stanford University, Stanford, California 94305-6104, United States
2. Center for Device Thermography and Reliability, University of Bristol, Bristol BS8 1TL, U.K.
3. George W. Woodruff School of Mechanical Engineering and Heat Lab, Georgia Institute of Technology, Atlanta, Georgia 30332-0405, United States
4. Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States