According to an exemplary embodiment, a method for fabricating a MOS transistor, such as an LDMOS transistor, includes forming a gate stack over a well. The method further includes forming a recess in the well adjacent to a first sidewall of the gate stack. The method further includes forming a source region in the recess such that a heterojunction is formed between the source region and the well. The method further includes forming a drain region spaced apart from a second sidewall of the gate stack. In one embodiment, the source region can comprise silicon germanium and the well can comprise silicon. In another embodiment, the source region can comprise silicon carbide and the well can comprise silicon.