wherein a thickness of the Mg Ag layer is in {TAIL ~ a range} of {HEAD ~ 170 Å} to 200 Å, 
wherein a thickness of the Mg Ag layer is in { TAIL ~ a range } of { HEAD ~ 170 Å } to 200 Å ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH