Split-gate field-effect transistor

We propose a new field-effect transistor (FET) where the gate voltage swing (i.e., the difference between the gate voltage and the threshold voltage) is varied along the channel in such a way that charge carriers are accelerated more rapidly and the average carrier velocity in the channel is increased. This can be achieved either by making the threshold voltage to be a function of position or by using a new device structure—split-gate FET (SFET). In both cases a smaller gate voltage swing close to the source leads to a higher electric field in this portion of the channel and, hence, to a more rapid increase of the carrier drift velocity with distance. Calculations of the device transconductances for a heterostructure SFET using a charge-control model show that the performance in the split-gate device is considerably improved compared to a conventional device. The improved electric field and potential distributions in a SFET should make it possible to utilize ballistic effects in this lateral device.