A method of fabricating a MOSFET is provided, including: depositing an oxide layer on a silicon substrate for device isolation; forming a silicon based alloy island above a gate region in the substrate, wherein the silicon based alloy comprises a silicon germanium alloy or a silicon tin alloy or another alloy of Group IV-B elements; building a sidewall about the silicon based alloy island; forming a source region and a drain region in the substrate; removing the silicon based alloy island, thereby leaving a void over the gate region; filing the void and the areas over the source region and the drain region; and planarizing the upper surface of the structure by chemical mechanical polishing. Alternative embodiments providing conventional and raised source/drain structures are disclosed.