Submicron MOSFET having asymmetric channel profile

A MOSFET semiconductor device having an asymmetric channel region between the source region and the drain region. In one embodiment, the device comprises a mesa structure on a silicon substrate with the source region being in the substrate and the mesa structure extending from the source region and substrate. The asymmetric channel region can include silicon abutting the source region and a heterostructure material such as Si1-xGex extending to and abutting the drain region. The mole fraction of Ge can increase towards the drain region either uniformly or in steps. In one embodiment, the doping profile of the channel region is non-uniform with higher doping near the source region and lower doping near the drain region.