But, the dark current by holes is reduced by providing an n type wide band gap layer with a larger band gap than the first layer and the π layer that suppresses {HEAD ~ the hole diffusion} between {TAIL ~ the first layer} and the π layer  
But , the dark current by holes is reduced by providing an n type wide band gap layer with a larger band gap than the first layer and the π layer that suppresses { HEAD ~ the hole diffusion } between { TAIL ~ the first layer } and the π layer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH