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A novel N-channel Si/SiGe heterostructure dynamic threshold voltage MOSFET (N-HDTMOS) has been proposed and fabricated. The Si/SiGe N-HDTMOS consists of an unstrained surface Si channel and heavily p-type doped SiGe body. The potential of the conduction band edge of the surface Si channel can be lowered by introducing a heavily p-type doped SiGe layer into a suitable position in the body region. As a result, the N-HDTMOS shows a threshold voltage reduction and a body effect factor (γ) enhancement while keeping high doping concentration in the SiGe layer. The fabricated SiGe N-HDTMOS exhibits superior properties, that is, 0.1 V reduction of Vth, 1.5 times enhancement of γ, and 1.3 times saturated current, as compared with those of Si N-DTMOS.
Date of Publication: Jan. 2004