Transconductance in nitride-gate or oxynitride-gate transistors

Experimental evidence is presented to support the argument that border traps are responsible for the anomalous shape of the transconductance-gate voltage curve in MOS transistors with nitride of oxynitride gate dielectric when compared with their oxide counterpart. Our measurements have revealed a high density of border traps in the gate dielectric containing a high concentration of nitrogen. These border traps appear to affect the transconductance in two ways: in the low gate field region, the trapping of carriers causes a significant reduction of the carrier density and thus a reduced transconductance, while in the high gate field region the "screening" effect of trapped carriers causes a smoothening of the electronic interface, and thus an increased transconductance.