Power Performance at 40 GHz of AlGaN/GaN High-Electron Mobility Transistors Grown by Molecular Beam Epitaxy on Si(111) Substrate

This letter reports on the demonstration of microwave power performance at 40 GHz on AlGaN/GaN high-electron mobility transistor grown on silicon (111) substrate by molecular beam epitaxy. A maximum dc current density of 1.1 $\text{A}\cdot $ mm $^{-1}$ and a peak extrinsic transconductance of 374 mS $\cdot $ mm $^{-1}$ are obtained for 75-nm gate length device. At $V_{\rm DS} = 25$ V, continuous-wave output power density of 2.7 $\text{W}\cdot $ mm $^{-1}$ is achieved at 40 GHz associated with 12.5% power-added efficiency and a linear power gain ( $G_{p})$ of 6.5 dB. The device exhibits an intrinsic current gain cutoff frequency $F_{T}$ of 116 GHz and a maximum oscillation frequency $F_{\rm MAX}$ of 150 GHz. This performance demonstrates the capability of low cost microwave power devices up to Ka-band.