In this paper, a methodology for the analysis of a resonant cavity enhanced (RCE) photodetector, based on internal photoemission effect and working at 1.55 μm, is reported. In order to quantify the performance of photodetector, quantum efficiency including the image force effect, and its dependence from the inverse voltage applied, are calculated. We propose a comparison among three different Schottky barrier Silicon photodetectors, having as metal layers gold, silver or copper respectively. We obtain that the highest efficiency (0.2%) is obtained with metal having the lowest barrier (Copper). The device fabrication is completely compatible with standard silicon technology.