This paper presents the simulation of mid-infrared InAs/GaSb superlattice (SL) detectors by using a finite element FEMLAB code, which is a practical and useful tool to characterize and to define microelectronic devices with appropriate geometry. In the framework of this FEMLAB code, the electro-optic performances of the SL photodetectors for room temperature (RT) operation are theoretical evaluated in terms of zero-bias resistance-area product R"0A and of external quantum efficiency @h in order to estimate the specific detectivity D^*. In the case of realistic SL active zone, calculated results show an optimal active zone thickness of about [email protected] and a RT specific detectivity D"@l^*=2x10^9cmW^-^1Hz^1^/^2 at @[email protected] This expected value demonstrates that InAs/GaSb SL detector is a competitive technology suitable for third generation detectors.