Fabrication of a n–p–p tunnel junction for a protocrystalline silicon multilayer/amorphous silicon tandem solar cell

Abstract We have fabricated a n-μc-Si:H/p-a-Si:H/p-a-SiC:H tunnel junction for a protocrystalline silicon (pc-Si:H) multilayer/amorphous silicon (a-Si:H) tandem solar cell. In order to improve the hole injection from the a-Si:H bottom cell, we insert a thin conductive p-a-Si:H layer between the n-μc-Si:H and p-a-SiC:H layers. We deposit all layers by the photo-CVD method. Due to ion-damage free characteristics, we could obtain high quality films. We measure the current–voltage ( I – V ) characteristic and activation energy in order to characterize the fabricated tunnel junction. We have applied this n–p–p tunnel junction to a pc-Si:H multilayer/a-Si:H tandem solar cell and achieved 9.24% energy conversion efficiency whereas only 7.84% efficiency was obtained for a tandem solar cell with no p-a-Si:H insertion layer.