Hui Xu,
Siddharth Alur,
Yaqi Wang,
An-Jen Cheng,
Kilho Kang,
Yogeshkumar Sharma,
Minseo Park,
Claude Ahyi,
John Williams, Chaokang Gu,
Andrew Hanser,
Tanya Paskova,
Edward A. Preble,
Keith R. Evans,
Yi Zhou
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ABSTRACT: We have fabricated vertical Schottky rectifiers based on a free-standing GaN substrate and have measured the temperature of
the device under operation insitu using micro-Raman spectroscopy. The n-type bulk GaN wafer with 500μm thickness was prepared using hydride vapor-phase epitaxy. The carrier concentration of the wafer was ~2.4×1016cm−3. Semitransparent Ni and multilayered Ti/Al/Pt/Au were used to make a Schottky and a full backside ohmic contact, respectively.
In this investigation, Raman spectra were collected as a function of the forward power applied to the Schottky diode. A systematic
shift and broadening of the Raman E
2 peak were observed as a function of increasing bias. This was caused by device heating due to the increase in current as
the forward bias was increased. It was demonstrated that micro-Raman spectroscopy can serve as an excellent insitu diagnostic tool for analyzing thermal characteristics of the GaN Schottky diode. Moreover, the strain caused by the piezoelectric
effect was calculated to lead to a shift of the Raman peak at the level of 0.001cm−1. This confirmed that the observed Raman peak shift was predominantly produced by a thermal not piezoelectric effect.
KeywordsGaN-Schottky rectifier-Raman spectroscopy
Journal of Electronic Materials 04/2012; 39(10):2237-2242. · 1.47 Impact Factor
