RECESSED-GATE DOPED-CHANNEL HETERO-MISFETS (DMTS) FOR HIGH-SPEED LASER DRIVER IC APPLICATION

Recessed-gate DMTs (doped-channel hetero-MISFETs) with i-AlGaAs/n-GaAs structure and pseudomorphic i-AlGaAs/n-InGaAs/i-GaAs structure have b een developed. Broad plateaus in g(m) and f(T) provide evidence that t he DMTs make the devices suitable for high-speed large-signal operatio n. GaAs DMTs with 0.35 mum-length have gate turn on voltage of 0.7 V, maximum transconductance of 320 mS/mm and f(T) of 41 GHz. Pseudomorphi c DMTs have gate turn on voltage of 0.9 V, maximum transconductance of 320 mS/mm, f(T) of 42 GHz and have the enhanced advantages of high cu rrent drivability and large gate swing. Further more, with the use of the recessed-gate DMTs, a high-speed laser driver IC for multi-Gb/s op tical communication systems are demonstrated. This laser driver IC ope rates at 10 Gb/s with rise and fall times as fast as 40 psec, and it c an drive up to 60 mA into a 25 OMEGA load.