Fabrication and performance characteristics of high-speed ion-implanted Si metal-semiconductor-metal photodetectors

We have fabricated high-speed Si metal-semiconductor-metal photodetectors using(19) F(+) ion implantation in low-doped Si. Bandwidths in excess of 6 GHz have been obtained that represent more than an order-of-magnitude improvement over unimplanted counterparts. Measurements with short optical pulses show that the increase in bandwidth is due primarily to a shorter carrier lifetime in implanted devices. In the absence of implantation, the response under short optical pulse excitation has a long decay with a time constant of ~0.35 ns. We carried out an optical fiber transmission experiment using a GaAs (lambda ~ 0.85 mum) laser source and the implanted Si photodetector. Error-free transmission (bit error rate < 10(-11)) with good receiver sensitivity was obtained at 2 Gbits/s. These results demonstrate that implanted Si can be used as a detector for short-wavelength fiber-optic communication systems for speeds to a few gigabits per second. Monolithic integration of this detector technology with conventional Si processing offers the potential for low-cost receiver designs.