A monolithically integrated silicon NMOS-PIN photoreceiver

For large-volume optoelectronics applications, the low cost, manufacturability and reliability of silicon MOSFET technology are advantageous. In addition, silicon photodetectors operate quite efficiently at the 0.8 /spl mu/m wavelength of economical AlGaAs light sources. In this paper, we report on a silicon-based monolithic optical receiver. The fabrication of the integrated lightwave receiver was carried out on a nominally undoped p-type Si substrate. The p-i-n photodetector was fabricated directly on the high-resistivity substrate so that the thickness of the detector depletion layer was approximately equal to the optical absorption length of 0.8 /spl mu/m light in silicon. A more heavily-doped p-well was formed for the NMOSFET fabrication. The silicon photodiodes had a dark current of 20 nA at 5 V, a break-down voltage greater than 60 V, and a zero-bias capacitance of 40 fF. The external quantum efficiency of the photodiode at 870 nm was approximately 45% at 5 V without an AR coating, and the bandwidth of the device was approximately 1.5 GHz. Frequency response evaluation of the receiver indicated a bandwidth of 30 MHz with open eye diagrams demonstrated at 40 MB/s.