Threshold Voltage Variation in SOI Schottky-Barrier MOSFETs

The inhomogeneity of Schottky-barrier (SB) heightΦBis found to strongly affect the threshold voltageVₜₕof SB-MOSFETs fabricated in ultrathin body silicon-on-insulator (SOI). The magnitude of this influence is dependent on gate oxide thicknesstₒₓand SOI body thicknesstₛᵢ; the contribution of inhomogeneity to theVₜₕvariation becomes less pronounced with smallertₒₓand/or largertₛᵢ. Moreover, an enhancedVₜₕvariation is observed for devices with dopant segregation used for reduction of the effectiveΦB. Furthermore, a multigate structure is found to help suppress theVₜₕvariation by improving carrier injection through reduction of its sensitivity to theΦBinhomogeneity. A new method for extraction ofΦBfrom room temperature transfer characteristics is also presented.