Hui Xu1, Siddharth Alur1, Yaqi Wang1, An-Jen Cheng1, Kilho Kang1, Claude Ahyi1, John Williams1, Minseo Park1*, Chaokang Gu2, Andrew Hanser3, Tanya Paskova3, Edward A. Preble3, Keith R. Evans3, and Yi Zhou4
1Department of Physics, Auburn University, Auburn, AL 36849 2Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, 36849 3Kyma Technologies, Inc., 8829 Midway West Road, Raleigh, NC 27617 4Department of Electrical Engineering, University of California, Los Angeles, CA 90095 *corresponding authorKeywords: GaN, Schottky diode, Raman
Intensive research has been focused on the GaN based electronic devices due to their intrinsic properties such as large band gap, high critical breakdown field and high electron saturation velocity, which provide great potential for high power and high frequency applications. Schottky diodes are useful components for high power electronics because of their fast switching. However, a significant limitation of device performance is the self-heating problem. Therefore, accurate determination of the device temperature is very important. In our experiment, we fabricated vertical Schottky rectifiers based on freestanding GaN substrate, where semi-transparent Ni was patterned on the Ga-face as the Schottky contact and full backside ohmic contact Ti/Al/Pt/Au was deposited on the N-face. Afterwards, Raman spectra were collected as a function of forward bias. The Raman E2 peak was found to shift and broaden systematically with device operating power. We conclude that micro-Raman spectroscopy is a great non-contact tool to monitor the thermal characteristics of electronic devices under operation.