Planar GaAs p-i-n photodiode with picosecond time response

A high-speed planar GaAs p-i-n photodiode has been fabricated on a semi-insulating GaAs substrate. The time response and sensitivity have been characterized in the wavelength range typical of GaAlAs diode lasers. An optoelectronic correlation measurement technique was used to determine the time response. The device exhibits an impulse response of 19 ps full width at half-maximum to 4-ps near-infrared dye laser pulses with an external quantum efficiency of 15%. The device is operated at the low bias voltage of −2 V. The planar electrode design and fabrication on a semi-insulating substrate make the diode suitable for incorporation in monolithic optoelectronic circuits.