Influences of /spl delta/-doping position on the characteristics of SiGe-Si DCFETs

SiGe-Si doped channel field-effect-transistors with different positions of /spl delta/ layers in SiGe wells have been proposed and fabricated. High forward gate to drain turn-on voltage (>0.87 V) and reverse breakdown voltage up to 25 V was obtained for center and bottom /spl delta/-doped channel devices. For device structures with the same 1×100 μm² gate, center /spl delta/-doped channel device display the best dc maximum extrinsic transconductance of 22.1 mS/mm. Compared with conventional Si-SiGe MODFETs, center /spl delta/-doped channel device exhibits improved gate voltage swings as wide as 3 V due to the better carrier confinement and the absence of parallel conduction, which is promising to provide an additional degree of freedom for Si-based device applications.