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