Origin of Soft Breakdown in Thin-Barrier AlGaN/GaN SBD With C-Doped GaN Buffer
Hao Wu, Xuanwu Kang, Yingkui Zheng, Wei Ke, Rikang Zhao, Yafei Yuan, Xinyu Liu, Guoqi Zhang
Abstract
In this work, we investigate the soft breakdown (BD) behavior in thin-barrier (TB) AlGaN/GaN Schottky barrier diode (SBD) with carbon-doped GaN buffer. The soft BD behavior is the result of the coupling of multiple mechanisms. In the off-state, the ionized carbon (C) acceptors make the electric field ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}$ </tex-math></inline-formula> -field) crowd at the cathode and cause the impact ionization. Then, the holes generated by impact ionization compensate with the ionized C acceptors, thus suppressing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}$ </tex-math></inline-formula> -field crowding and preventing the further avalanche BD. The residual holes flow to and accumulate under the anode, which leads to a continuous increase in the Schottky <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}$ </tex-math></inline-formula> -field and Schottky leakage, eventually causing the soft BD. Due to the tunneling effect, Schottky leakage is highly sensitive to the Schottky <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}$ </tex-math></inline-formula> -field in TB structure, so the leakage rise rate during soft BD is abnormally high.