Sharp Logic Switch Based on Band Modulation

The capability of Z
²
-FET (Zero Impact Ionization and Zero Subthreshold Slope FET) to operate as a sharp logic switch is demonstrated in advanced FD-SOI (Fully Depleted SOI) technology. The operation mechanism is band-modulation which enables remarkable DC performance in terms of ON/OFF current ratio and sharp switch (~1 mV/decade). Z
²
-FETs have successfully been used for ESD protection and capacitorless DRAM memory, but the presence of an inherent hysteresis has handicapped so far logic applications. However, this letter shows that fast pulses on the gate result in hysteresis-free switching: the device turns ON and OFF at same gate bias. The sharpness of the switch depends on device parameters, bias and speed of operation. Systematic experiments compare the performance of Z
²
-FETs with dual or single ground-planes.