A novel metamorphic high electron mobility transistors with (InxGa1-xAs)m/(InAs)n superlattice channel layer for millimeter-wave applications
High performance MHEMTs using (In<inf>x</inf>Ga<inf>1-x</inf>As)<inf>m</inf>/(InAs)<inf>n</inf> superlattice structure as a channel layer have been fabricated successfully. These HEMTs with 80 nm gate length exhibit high drain current density of 392 mA/mm at drain bias 1.0 V and transconductance of 991 mS/mm at drain bias 1.2 V. Comparison with regular In<inf>x</inf>Ga<inf>1-x</inf>As channel, the superlattice channel HEMTs show an outstanding performance because of high electron mobility, and better carrier confinement in the (In<inf>x</inf>Ga<inf>1-x</inf>As)<inf>m</inf>/(InAs)<inf>n</inf> channel layer. The current gain cutoff frequency (f<inf>T</inf>) and maximum oscillation frequency (f<inf>max</inf>) were extracted to be 304 GHz and 162 GHz, respectively. The device demonstrated a 0.75 dB noise figure with an associated gain 9.6 dB at 16 GHz. The excellent device performance shows that the superlattice channel can be practically used for high-frequency and millimeter-wave application.