The leakage current of SOI based Floating Body Memory (FBM) has been modeled. The model takes into account oxide/SOI interface traps (Dit) and Electric Field Enhanced (EFE) generation of electron hole pairs (EHPs) from trap states via the Poole-Frenkel Effect (PFE). This model has been used to improve the retention time of Z-RAM by a reduction of both Dit and electric field. It can also be extended to SOI based low power devices.