The first and second electrodes are separately disposed on {HEAD ~ the epitaxial layer structure}, and the epitaxial layer structure has {TAIL ~ a root means square roughness} less than about 3 at a surface whereon the first electrode is formed 
The first and second electrodes are separately disposed on { HEAD ~ the epitaxial layer structure } , and the epitaxial layer structure has { TAIL ~ a root means square roughness } less than about 3 at a surface whereon the first electrode is formed
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH