The embodiments of processes and structures described provide mechanisms for improving the mobility of carriers. A dislocation is formed in a source or drain region between gate structures or between a gate structure and an isolation structure by first amortizing the source or drain region and then recrystallizing the region by using an annealing process with a low pre-heat temperature. A doped epitaxial material may be formed over the recrystallized region. The dislocation and the strain created by the doped epitaxial material in the source or drain region help increase carrier mobility.