Effect of doping profile on the potential performance of buried channel SiGeC/Si heterostructure MOS devices

We investigate in this paper issues related to the charge control and direct tunneling gate leakage of buried channel SiGeC MOSFETs entering the deep sub-View the MathML source gate length range. Within the study of SiGeC heterostructure MOS capacitors with a Schrödinger–Poisson solver, we show that with doping levels required to control short channel effects of such ultra-short gate length devices, i.e. higher than View the MathML source, it is extremely hard to maintain a significant part of the electron density into the buried quantum well. It is shown that the spacer layer has thus to be kept as thin as possible to benefit from strain enhancement of carrier transport. We prove that such a MOSFET channel design is compatible with a rather strong reduction of gate leakage (∼10) obtained through purely-strain-induced properties.