PIN JUNCTION PHOTOVOLTAIC ELEMENT HAVING AN I-TYPE SEMICONDUCTOR LAYER WITH A PLURALITY OF REGIONS HAVING DIFFERENT GRADED BAND GAPS

摘要

A pin junction photovoltaic element having an i-type semiconductor layer formed of a band gap variable semiconductor material between a p-type semiconductor layer having a band gap wider than that of said i-type semiconductor layer and an n-type semiconductor layer having a band gap wider than that of said i-type semiconductor layer, characterized in that said i-type semiconductor layer contains a first region which is positioned on the side of said p-type semiconductor layer and has a graded band gap, a second region which is adjacent to said first region and has a graded band gap, and a third region which is positioned on the side of said n-type semiconductor layer and has a graded band gap; said i-type semiconductor layer has a minimum band gap at the boundary between said first region and said second region; the thickness of said first region is less than one second of the thickness of said i-type semiconductor layer; and the gradient of the graded band gap of said third region is larger than that of the band gap of said second region.