Unusual floating body effect in fully depleted MOSFETs

The transconductance of fully depleted SOI MOSFETs may feature a sudden drop to zero. This surprising behavior, observed for low as well as high drain voltage, exhibits hysteresis, time dependence, and other intriguing properties. The experimental conditions are systematically investigated and a preliminary model is proposed. The new effect is a combination of several mechanisms: floating body, back-gate biasing, transient drain and gate currents, and poly-depletion.