Integrated BiCMOS p-i-n Photodetectors With High Bandwidth and High Responsivity

The integration of the fast and efficient silicon p-i-n photodetectors is presented. The suggested advanced p-i-n design speeds up the detectors, avoiding slow carrier diffusion: the p
⁺
anode is arranged in a thick n
^$
low-doped intrinsic region placed inside an n
⁺
-doped region. Two p-i-n detector concepts are compared: a plain p-i-n photodiode and a structured p-i-n fingerdiode that is optimized for shorter wavelengths. Due to this setup and a thick intrinsic region, a responsivity of R=0.25 A/W (0.42 A/W) {0.27 A/W} at a wavelength of lambda=410 nm (660 nm) {850 nm} for the p-i-n fingerdiode, a bandwidth up to f
_3dB
=3GHz and a dark current of I
_dark
=0.36 pA at V
_p-
i
_-
n=17 V for the p-i-n photodiode could be reached. As a system-on-chip (SOC), BiCMOS circuitry is combined with the integrated photodetector to an optoelectronic integrated circuit (OEIC) as shown on an exemplary application of a 6-Gb/s monolithic optical receiver. The chips are realized in a modified 0.5 mum BiCMOS process