Ultra-thin body (UTB) SOI MOSFETs are considered as one of most promising candidates for deca-nano-scale regimes. The device characteristics of two different UTB MOSFETs with raised source/drain (RSD) and lowered source/drain (LSD), respectively, are investigated with DC and AC considerations. The results suggest that LSD-UTB SOI MOSFETs show better control of the off-state leakage current, about one order of magnitude lower than that of RSD-UTB MOSFETs. The short-channel effect (SCE) and drain-induced-barrier-lowering (DIBL) effect are more effectively suppressed in LSD-UTB MOSFETs. And the intrinsic delay of LSD-UTB device is smaller than that of RSD-UTB as a result of the greatly reduced parasitic capacitance. In addition, the LSD-UTB MOSFETs demonstrate better scaling capability than RSD-UTB MOSFETs. And LSD-UTB can greatly relax the requirement for silicon body thickness by similar to60%. (C) 2004 Elsevier Ltd. All rights reserved.