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