Vertical GaN Schottky Barrier Diode With Record Low Contact Resistivity on N-Polarity Using Ultrathin ITO Interfacial Layer
Xinke Liu, Haofan Wang, Junye Wu, Ping Zou, Yudi Tu, Shaojun Chen, Xinbo Xiong, Xinzhong Wang, Jiajun Han, Wenrong Zhuang, Zhichao Yang, Feng Qiu, Hsien‐Chin Chiu, Ze Zhong
Abstract
In this article, an ohmic contact structure based on indium tin oxide (ITO)/Ti/Al/Ni/Au is explored for high-performance GaN-on-GaN Schottky barrier diode (SBD) for the first time. Owing to the ultrathin ITO interfacial layer, the Fermi-level pinning (FLP) effect in metal-semiconductor interface could be mitigated, thus the specific contact resistivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rho _{c}{)}$ </tex-math></inline-formula> on N-polarity was reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.32\times 10^{-{3}}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.36\times 10^{-{5}}\,\,\Omega $ </tex-math></inline-formula> cm2, and the specific ON-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ON}}{)}$ </tex-math></inline-formula> of the device was reduced from 3.14 to 1.17 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> cm2 under the same testing condition. With the Helium ion implantation technology, a high breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {BR}}{)}$ </tex-math></inline-formula> of 1100 V, low turn-on voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {ON}}$ </tex-math></inline-formula> of 0.63 V, and a high figure of merit ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {BR}}^{{2}}/{R}_{\text {ON}}{)}$ </tex-math></inline-formula> of 1.04 GW/cm2 were achieved in this work. The vertical GaN SBD with ITO interfacial layer fabricated in this work achieved the lowest <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rho _{c}$ </tex-math></inline-formula> in the reported GaN-on-GaN SBDs with an indicated anode size.