Interdigitated electrode and coplanar waveguide InAlAs/InGaAs MSMphotodetectors grown by LP MOVPE

摘要

The authors report on the layout and performance of interdigitatedelectrode and coplanar waveguide metal-semiconductor-metal (MSM)photodetectors based on the InAlAs/InGaAs material system and grown bylow pressure metal-organic vapor phase epitaxy (LP-MOCVD). Both thelow-capacitance interdigitated electrode and the impedance-matchedcoplanar waveguide structure exhibit a dynamic behavior with 35-psrising time, but with a slow turn-off behavior (full width at halfmaximum=225 ps), which is determined by the transit time of thephotogenerated carriers. The coplanar waveguide has an active area of1.6×10-3 cm2 and a space charge capacitanceof 200 pF. The results for this waveguide demonstrate that animpedance-matched large-area device may work withoutRC-limitation. Using this concept, high-speed operation is nolonger limited to small-area devices