After distributing a nonmetal element in {TAIL ~ a region} in the vicinity of {HEAD ~ a surface portion} of a semiconductor layer, a metal film is deposited on the semiconductor layer 
After distributing a nonmetal element in { TAIL ~ a region } in the vicinity of { HEAD ~ a surface portion } of a semiconductor layer , a metal film is deposited on the semiconductor layer
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH