Band Engineered (Heterostructure) IMOS Device

A novel model for impact ionization metal-semiconductor (IMOS) device with an engineered bandstructure (heterostructure) has been proposed and simulated. The IMOS intrinsic, wherein the carrier generation is mainly due to impact ionization, controls the band to band tunneling. In the proposed model, it is assumed the intrinsic region to be SixGe1−x (0.5≤x≤1) whose bandgap varies linearly from that of Si at the source edge to that of Si0.5Ge0.5 at the gate edge. Maximum gap difference of ΔEG=ΔEC=0.32 eV appears at the source /intrinsic region interface. As a consequence, the probability of band to band tunneling and hence the device dark current is reduced. The numerical result shows that the breakdown voltage and the dark current for the proposed heterostructure IMOS are respectively ~0.3 V and four times smaller than those of the homojunction Si0.5Ge0.5-IMOS, with the same dimensions.