Low capacitance, front-illuminated planar InGaAs PIN photodiode on semi-insulating InP substrate

Abstract

We have developed a simple, high yield process to fabricate low-capacitance, front-illuminated InGaAs/InP pin photodiodes on semi-insulating InP substrate. The fabricated devices have a very low capacitance smaller than 0.15pF with a 30 /spl mu/m junction diameter. The measured responsivity using fiber coupling is as high as 0.78 A/W at a wavelength of 1.55/spl mu/m. The low-capacitance photodiode results in a 3-dB bandwidth of 14.8 GHz which appears to be limited by carrier transit time rather than the RC time constant. These characteristics are expected to meet the stringent requirements in high speed and high sensitivity lightwave systems.