InGaSb n-MOSFET: Modeling & Performance Analysis

Abstract

Antimonide-based III-V materials are highly interested in the channel of low power and high-speed all-antimonide CMOS digital logic devices. In this thesis work InGaSb-based double gate (DG) nMOSFET architectures with DG-nMOSFET are proposed and numerically simulated. To assess and hence to compare the ballistic performance of DG-JnMOSFET and, non-equilibrium greens function method is utilized under the framework of well-known SILVACO’s ATLAS device simulation package without taking into account of scattering. Wave function penetration to the oxide is taken into account in the simulation. In this study the effect of gate length on drain current and other logic figures of merit like subthreshold slope (SS), ION, IOFF, and ION/IOFF are investigated. The results obtained for DG-nMOSFET demonstrate that there is negligible dependence on the “ON” current with the gate length. Small increase in the OFF current is found for decreasing gate length from 15 nm to 13 nm, however, the OFF current increases significantly when the gate length decreases from 13 nm. Subthreshold slope decreases with increasing gate length. The maximum subthreshold swing is evaluated 80 mV/decade for the gate length 7nm, which reduces to 70 mV/decade for the gate length 15 nm. Also the threshold voltage decreases with decreasing gate length. Effect of the gate oxides (Al2O3 and HfO2) in same equivalent oxide thickness (EOT) is also studied. The shift in threshold voltage and change in ION/IOFF are found strong dependence with gate oxides having different dielectric constants. Further, the effect of gate underlap is analyzed for the gate lengths 10nm and 15nm with different underlap lengths. Drain current found to vary significantly for different underlap lengths when gate length is 10nm. However, for the gate length 15 nm the variation of drain current is insignificant with underlap length. The threshold voltage is also found to have strong dependence with gate length and gate underlap length.