Experimental I–V and C–V Analysis of Schottky-Barrier Metal-Oxide-Semiconductor Field Effect Transistors with Epitaxial NiSi_2 Contacts and Dopant Segregation

We present an experimental analysis of Schottky-barrier metal-oxide-semiconductor field effect transistors (SB-MOSFETs) fabricated on ultrathin body silicon-on-insulator substrates with a steep junction by the dopant implantation into the silicide process. The subthreshold swing of such SB-MOSFETs reaches 69 mV/dec. Emphasis is placed on the capacitance-voltage analysis of p-type SB-MOSFETs. According to the measurements of gate-to-source capacitance C_\rm gs with respect to V_\rm gs at various V_\rm ds, we find that a maximum occurs at the accumulation regime due to the most imbalanced charge distribution along the channel. At each C_\rm gs peak, the difference between V_\rm gs and V_\rm ds is equal to the Schottky barrier height (SBH) for NiSi_2 on highly doped silicon, which indicates that the critical condition of channel pinching off is related with SBH for source/drain on channel. The SBH for NiSi_2 on highly doped silicon can affect the pinch-off voltage and the saturation current of SB-MOSFETs.