The method 6, wherein the first refractive index adjustment layer is formed on {HEAD ~ the n type nitride semiconductor layer} and has {TAIL ~ a refractive index} less than that of the n type nitride semiconductor layer, and 
The method 6 , wherein the first refractive index adjustment layer is formed on { HEAD ~ the n type nitride semiconductor layer } and has { TAIL ~ a refractive index } less than that of the n type nitride semiconductor layer , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH