A 200-GHz True E-Mode Low-Noise MHEMT

In this paper, a fully passivated true Enhancement-mode 110-nm metamorphic high-electron mobility transistor (E-MHEMT) on GaAs substrate with excellent dc and RF performance has been developed. By choosing an indium content of 40% for the AlInAs/GaInAs/AlInAs MHEMT, the difference between the Schottky-barrier height and the conductance band-offset (channel/barrier) of the device is enhanced compared with 53% indium devices lattice matched to an InP substrate. A true E-MHEMT is demonstrated with an extremely low leakage current, wide gate-voltage swing, and excellent dynamic performance. The threshold-voltage standard deviation is only 12 mV on four wafers. The device presents an excellent unity gain cutoff frequency of 204 GHz with state-of-the-art $\hbox{NF}_{\min} = \hbox{0.69}\ \hbox{dB}$ and $\hbox{Gass} = \hbox{10}\ \hbox{dB}$ at 30 GHz. This transistor is a good candidate for high-speed digital, high-frequency analog, or mixed applications, where the low noise, low-power consumption, and digital capabilities of this technology are distinct advantages.