Schottky Photodiodes in Bulk CMOS for High-Speed 1310/1550 nm Optical Receivers

This paper presents a very thorough analysis of the potential of Schottky diodes as photodetectors for fully integrated optical receivers in bulk CMOS. By absorbing photons in the metal, these devices can detect the 1310/1550 nm telecommunication wavelengths, unlike silicon PN-diodes. Moreover, besides being sensitive to a broader range of wavelengths, Schottky photodiodes in CMOS have a very high intrinsic bandwidth. Schottky photodiodes of various types and sizes were fabricated in several bulk CMOS processes. As a case study, the photodiodes in 40 nm CMOS have been extensively characterized. By enabling 1310/1550 nm detection in CMOS, we envision that optical receivers for these applications will become significantly cheaper, smaller, lower power, and more densely integrated.