A semiconductor device comprising: A substrate comprising a gate electrode formed over a channel region of the substrate , and a recessed source interface and a recessed drain interface formed on the substrate at opposite sides of the gate electrode ; a first spacer and a second spacer formed on opposite sidewalls of the gate electrode , wherein a portion of the recessed source interface extends laterally beneath the bottom surface of the first spacer , and a portion of the recessed drain interface extends laterally beneath the bottom surface of the second spacer ; a source region comprising a first epitaxial region formed over the recessed source interface , and a first cap layer formed over the first epitaxial region , wherein a portion of the first cap layer is formed between the first epitaxial region and the bottom surface of the first spacer ; and a drain region comprising a second epitaxial region formed over the recessed drain interface , and a second cap layer formed over the second epitaxial region , wherein a portion of the second cap layer is formed between the second epitaxial region and the bottom surface of the second spacer , characterized in that the first and second epitaxial regions each comprises silicon and carbon doped with phosphorus, wherein the first and second epitaxial regions each comprises silicon having a carbon concentration in the range of 0.5 atomic % to 4 atomic %, anda phosphorus concentration in the range of 9E19 cm-3 to 3E21 cm-3, and wherein each of the first and second cap layers is a phosphorous doped silicon cap layer having a phosphorus concentration in the range of 8E19 cm-3 to 3E21 cm-3. a gate electrode formed over a channel region of the substrate , and a recessed source interface and a recessed drain interface formed on the substrate at opposite sides of the gate electrode ; a first spacer and a second spacer formed on opposite sidewalls of the gate electrode , wherein a portion of the recessed source interface extends laterally beneath the bottom surface of the first spacer , and a portion of the recessed drain interface extends laterally beneath the bottom surface of the second spacer ; a source region comprising a first epitaxial region formed over the recessed source interface , and a first cap layer formed over the first epitaxial region , wherein a portion of the first cap layer is formed between the first epitaxial region and the bottom surface of the first spacer ; and a first epitaxial region formed over the recessed source interface , and a first cap layer formed over the first epitaxial region , wherein a portion of the first cap layer is formed between the first epitaxial region and the bottom surface of the first spacer ; and a drain region comprising a second epitaxial region formed over the recessed drain interface , and a second cap layer formed over the second epitaxial region , wherein a portion of the second cap layer is formed between the second epitaxial region and the bottom surface of the second spacer , a second epitaxial region formed over the recessed drain interface , and a second cap layer formed over the second epitaxial region , wherein a portion of the second cap layer is formed between the second epitaxial region and the bottom surface of the second spacer , characterized in that the first and second epitaxial regions each comprises silicon and carbon doped with phosphorus, wherein the first and second epitaxial regions each comprises silicon having a carbon concentration in the range of 0.5 atomic % to 4 atomic %, anda phosphorus concentration in the range of 9E19 cm-3 to 3E21 cm-3, and wherein each of the first and second cap layers is a phosphorous doped silicon cap layer having a phosphorus concentration in the range of 8E19 cm-3 to 3E21 cm-3. <EOS>