Solar cell and manufacturing method thereof

Abstract

A solar cell includes a semiconductor substrate of a first conductivity; a pillar-shaped structure constituted by a semiconductor of the first conductivity, the pillar-shaped structure being formed on the semiconductor substrate; a superlattice layer including a barrier layer and a quantum structure layer that are alternately deposited on a side wall of the pillar-shaped structure, the quantum structure layer being constituted by a material having a smaller energy bandgap than that of the barrier layer, the quantum structure layer including a wurtzite type crystal part and a zinc blende type crystal part that are alternately arranged along an axial direction of the pillar-shaped structure; and a semiconductor layer of a second conductivity that is formed so as to surround the superlattice layer, the second conductivity being an opposite conductivity to that of the first conductivity.

1 - 7 . (canceled) 
     
     
         8 . A manufacturing method of a solar cell, the manufacturing method comprising:
 forming a pillar-shaped structure of a first conductivity on a semiconductor substrate of the first conductivity, the pillar-shaped structure being formed by alternately growing a semiconductor of a wurtzite type crystal and a semiconductor of a zinc blende type crystal such that a wurtzite type crystal part and a zinc blende type crystal part are alternately arranged along an axial direction;   forming a superlattice layer by alternately depositing a barrier layer and a quantum structure layer so as to surround the pillar-shaped structure, the quantum structure layer being constituted by a material having a smaller energy bandgap than that of the barrier layer, a part of the superlattice layer contacting the wurtzite type crystal part of the pillar-shaped structure being a wurtzite type crystal and a part of the superlattice layer contacting the zinc blende type crystal part of the pillar-shaped structure being a zinc blende type crystal; and   depositing a semiconductor layer of a second conductivity so as to surround the superlattice layer, the second conductivity being an opposite conductivity to that of the first conductivity.   
     
     
         9 . The manufacturing method according to  claim 8 , wherein
 the forming of the superlattice layer includes selectively forming the superlattice layer on a side wall part of the pillar-shaped structure.   
     
     
         10 . The manufacturing method according to  claim 8 , wherein
 the forming of the superlattice layer includes forming the superlattice layer so as to cover a side wall part and a top part of the pillar-shaped structure.