Near-Infrared All-Silicon Photodetectors

We report the fabrication and characterization of all-silicon photodetectors at 1550 nm based on the internal photoemission effect. We investigated two types of structures: bulk and integrated devices. The former are constituted by a Fabry-Perot microcavity incorporating a Schottky diode, and their performance in terms of responsivity, free spectral range, and finesse was experimentally calculated in order to prove an enhancement in responsivity due to the cavity effect. Results show a responsivity peak of about 0.01 mA/W at 1550 nm with a reverse bias of 100 mV. The latter are constituted by a Schottky junction placed transversally to the optical field confined into the waveguide. Preliminary results show a responsivity of about 0.1 mA/W at 1550 nm with a reverse bias of 1 V and an efficient behaviour in both C and L bands. Finally, an estimation of bandwidth for GHz range is deduced for both devices. The technological steps utilized to fabricate the devices allow an efficiently monolithic integration with complementary metal-oxide semiconductor (CMOS) compatible structures.