Extension of Universal Mobility Curve to Multi-Gate MOSFETs
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The concept of "universal mobility" was successfully extended to multi-gate transistors. We developed a novel method to determine the effective electric field (E<sub>eff</sub>) in multi-gate transistors experimentally taking all charges in and around the silicon body into account. By applying this method to double-gate (DG) transistors, we showed that E<sub>eff</sub> goes from positive to negative, which depends on whether the front- or back- side channel is dominant. The validity of the universal relationship between mu<sub>eff</sub> and E<sub>eff</sub> was confirmed even with negative E<sub>eff</sub>. Moreover, in the case of a symmetric DG transistor (V<sub>fg</sub>=V<sub>bg</sub>) like FinFETs, a high mu<sub>eff</sub> can be obtained even at high gate-overdrive voltages because E<sub>eff</sub> is always approximately zero.
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