Experimental Validation of Depolarization Field Produced Voltage Gains in Negative Capacitance Field-Effect Transistors

For the first time, this study experimentally validates that the depolarization field (E
_DE
) in the ferroelectric (FE) film leads to voltage gains in negative capacitance (NC) field-effect transistors (FETs). For both NCFETs with and without a floating gate, the steeper subthreshold swing (SS) and the enhanced I
_ON
are achieved under dc and pulse measurements corresponding to the measured voltage gains (dV
_int
/dV
_GS
> 1). Furthermore, the voltage gains are theoretically calculated based on the depolarization theory and the voltage distribution across the gate-stack, showing good agreements with the measured results. In conclusion, EDE in an FE film produces the NC effect and the voltage gains. Even with P <; 1.5 μC/cm
²
, sufficient EDE is still produced in NCFETs to achieve improved electrical performance over the reference MOSFET. These findings suggest a way for low-voltage and high-reliability NCFETs.