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

Abstract

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 $0.87~\Omega \cdot $ mm was obtained. The H-diamond RF MOSFET with gate length of $0.45~{\mu }\text{m}$ achieved a high current density of −549 mA/mm and an extrinsic ${f} _{\mathrm{ T}}/{f}_{\max }$ 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.

Keywords

• H-diamond
• bi-layer passivation
• output power