In this paper, a new approach for the near infrared sub-bandgap detection in Si-based devices is investigated. In particular, the design, the realization and the characterization of a back illuminated silicon resonant cavity enhanced Schottky photodetectors, working at 1.55 μm, are reported. The photodetectors are constituted by Fabry-Perot microcavity incorporating a Schottky diode. The working principle is based on the internal photoemission effect enhanced by cavity effect. Performances devices in terms of responsivity, free spectral range, finesse and estimated bandwidth are reported.