A new body tied to gate (BTG) n-channel metal-oxide-semiconductor field-effect-transistor (NMOSFET) with a diode in partially depleted SOI (PD SOI) is proposed and investigated. We first compare the transfer and output characteristics between the regular and BTG NMOSFETs with grounded body and floating body. The steep subthreshold slope (<6 mV/dec) and low OFF current (similar to 0.01 pA/mu m) of the BTG NMOSFET with floating body are observed at V-D = 3. 3 V. Mechanisms of the floating body effect (FBE) and the diode are analyzed to explain the outstanding performance. The hysteresis characteristics of BTG NMOSFETs are also presented in comparison to regular ones. Finally, the steep subthreshold characteristics of the BTG NMOSFET with floating body at low drain voltage are studied for ultralow power application. (C) 2017 Elsevier Ltd. All rights reserved.