each of said pair of SiGe mixed crystal regions including a main part formed right underneath an uppermost part of said SiGe mixed crystal region, said {HEAD ~ main part} having {TAIL ~ a sidewall surface}, 
having
each of said pair of SiGe mixed crystal regions including a main part formed right underneath an uppermost part of said SiGe mixed crystal region , said { HEAD ~ main part } having { TAIL ~ a sidewall surface } ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH