High-speed low-temperature-grown GaAs p-i-n traveling-wave photodetector

We report a novel type of p-i-n traveling-wave photodetector utilizing low-temperature-grown GaAs (LTG-GaAs). The devices show a record impulse response time (530-fs fullwidth at half-maximum, /spl sim/560 GHz -3-dB bandwidth) which agrees with theoretical estimates. The effects of various limiting factors on the device performance were analyzed theoretically and compared with measurements obtained by electrooptic characterization of our devices. Calculations indicate that the device speed is dominated by the short carrier lifetime. DC external quantum efficiencies as high as 8% were obtained.