1. Center for Device Thermography and Reliability (CDTR), H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K.
2. School of Advanced Materials and Nanotechnology, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi’an 710071, P. R. China
3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, P. R. China
4. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States