1 W/mm Output Power Density for H-Terminated Diamond MOSFETs With Al₂O₃/SiO₂ Bi-Layer Passivation at 2 GHz

• Main Authors: Xinxin Yu, Wenxiao Hu, Jianjun Zhou, Bin Liu, Tao Tao, Yuechan Kong, Tangsheng Chen, Youdou Zheng
• Format: Article
• Language: English
• Published: IEEE 2021-01-01
• Series: IEEE Journal of the Electron Devices Society
• Subjects: H-diamond; bi-layer passivation; output power
• Online Access: https://ieeexplore.ieee.org/document/9305694/

We have demonstrated a novel method of depositing ALD-Al₂O₃/PECVD-SiO₂ bi-layer dielectric to passive the surface channels of the hydrogen-terminated diamond (H-diamond). After Al₂O₃/SiO₂ passivation, the surface current increased with time and then tended to be saturated. Afterwards, it became much more stable and showed a larger current than an unpassivated counterpart. The H-diamond MOSFETs were fabricated by using this bi-layer passivation structure and an extremely low Ohmic contact resistance of <inline-formula> <tex-math notation="LaTeX">$0.87~\Omega \cdot $ </tex-math></inline-formula>mm was obtained. The H-diamond RF MOSFET with gate length of <inline-formula> <tex-math notation="LaTeX">$0.45~{\mu }\text{m}$ </tex-math></inline-formula> achieved a high current density of &#x2212;549 mA/mm and an extrinsic <inline-formula> <tex-math notation="LaTeX">${f} _{\mathrm{ T}}/{f}_{\max }$ </tex-math></inline-formula> of 15/36 GHz. By load-pull measurement, a high output power density of 1.04 W/mm was obtained at frequency of 2 GHz. The results reveal that it is a promising solution for high-stable and high-power diamond transistors by using the Al₂O₃/SiO₂ bi-layer passivation.