高截止频率优值的AlGaN/GaN异质结MSM-2DEG变容二极管

In this letter, we present the fabrication and characterization of metal-semiconductor-metal (MSM) varactors based on an AlGaN/GaN heterostructure, featuring two-dimensional electron gas (2DEG) channels. A novel device design employing $4~\mu $ m-length rectangular anodes combined with a 166 nm T-gate cathode and a narrowed device width of $10~\mu $ m is introduced to minimize the ${R}_{s} \cdot {C}_{j}$ constants and significantly enhance high-frequency performance. The optimized varactor demonstrates an extremely low normalized resistance ( ${R}_{s} \cdot {W}$ ) of $0.106~\Omega \cdot $ mm with a high capacitance switching ratio ${C}_{\textit {rati}{o}}$ of 3.04 and, the device achieves a record figure of merit (FOM) of 10.4 THz among GaN-based varactors. In comparison, a reference varactor with $2~\mu $ m-length rectangular anodes exhibits an FOM of 7.59 THz. The low leakage current density of ${1}.{33}\times {10} ^{-{7}}$ A/mm confirms robust metal-semiconductor contacts. This study also elucidates the dynamic evolution of carrier concentration in 2DEG channel of the heterojunction under bias voltage modulation, clarifying the characteristics of capacitance and resistance variations in response to the dynamic regulation of carrier concentration.