<title>Low-cost GaAs MESFET and InP HFET technologies for 40-Gb/s OEICs</title>

Abstract

40 Gb/s are expected to become the future standard fiber- optic operating speed for the data communication and telecommunication systems. High performance and low cost technologies are required to lower the system cost, yet maintain the overall performance. In this paper, a state of the art ion implant GaAs MESFET and a simple layer structure InP/InGaAs doped channel HFET were described, compared and proposed for 40 Gb/s OEICs. We have developed 0.10 (mu) M gate direct ion implanted GaAs MESFET process with current cutoff frequency (ft) of 120GHz which is the highest reported ft for 0.1 micrometers gate MESFET device. Bas4ed on this result, we believe a low cost solution of ion implant GaAs MESFET with ft greater than 200GHz process is available in the n ear future with 0.05micrometers gate. The 0.14 micrometers InP/InGaAs doped channel HFET has ft of 188GHz, which is the highest reported doped channel HFET device. The measured device performance of both devices are described in the paper. Compared to the epitaxial device, the ion implant MESFET has the significant advantage in the low cost solution of 40 Gb/s OEIC. The doped channel HFET provides superior performance than MESFET, yet it needs only 5 epitaxial layers which provide advantage over HEMT device. 40Gb/s OEIC receiver was studied and designed using HFET HSPICE model. The simulation shows the circuit has bandwidth of greater than 30GHz with greater than 40 dB ohms gain which make it suitable for 40 Gb/s application. Using this circuit, a 1 by 4 OEIC receiver array in a wavelength division multiplexing system will have overall data rate of 160 Gb/s.