Abstract
InP-based InGaAs/AlAs/InAs resonant tunneling diodes (RTDs) and a uni-traveling-carrier photodiode (UTC-PD) are monolithically integrated to construct an optoelectronic logic gate. RTD structures are regrown by molecular beam epitaxy on the top of UTC-PD structures grown by metalorganic chemical vapor deposition. The characteristics of the regrown RTDs are almost the same as those of conventional RTDs directly grown on semi-insulating InP substrates. The UTC-PD provides a sufficient current drivability along with a high-speed operation demonstrated by the 3-dB bandwidth of 80 GHz, even at the low bias voltage corresponding to the peak voltage of the RTD. An optoelectronic logic gate using two RTDs and one UTC-PD was fabricated. This simple optoelectronic logic gate exhibited high-speed delayed flip-flop operation of 40 Gbit/s at a small power consumption of 7.75 mW. These results suggest that an optoelectronic logic gate using RTDs and a UTC-PD is suitable for the construction of ultrahigh-speed and low-power optoelectronic circuits.