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

We have fabricated a n-mu c-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-mu c-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 pe-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. (c) 2006 Elsevier B.V. All rights reserved.