A metal-semiconductor-metal photodetector in Si-based, standard CMOS technologies

A metal-semiconductor-metal photodetector (MSM PD) that operates at a wavelength of 850 nm is presented based on Si-based, standard CMOS technologies. It consists of two back-to-back, interdigitated Metal1/Nwell schottky diodes. The MSM PD was designed and implemented in a Chartered 0.35 µm standard CMOS process. It has a measured responsivity of 0.21 A/W at low DC bias from 0.1 V to 5.4 V, which is almost larger than that of a standard CMOS, high-speed p-n junction photodetector by one order of magnitude. In addition, the measured photo-current-to-dark-current ratio is 8000 at 0.1V, and −3 dB bandwidth is 919 MHz. The good responsivity and large bandwidth, combined with its very low operating voltage and complete compatibility with standard CMOS processes, make this MSM PD a promising candidate for standard CMOS optoelectronic integrated receivers in short and ultra-short distance optical communications, and optical interconnects.