The solar cells were deposited using radio frequency plasmaenhanced
chemical vapor deposition (rf-PEVCD) using up-to-date
optimized deposition conditions. The single junction a-Si:H and μc-
Si:H solar cells were deposited in superstrate configuration on Corning
glass with ZnO:Al as front contact and ZnO:Al/Ag/ZnO:Al as back
contact/reflector. The thicknesses of the absorber layers in the single
junction cells were respectively 300 and 1000 nm. The tandem and
triple-junction cells were deposited on SnO2:F coated glass type Asahi-
VU. The tandem cells have superstrate configuration with a top a-Si:H
p-i-n, n-type μc-Si:H as the tunnel recombination junction (TRJ) and a
bottom μc-Si:H p-i-n [17]. The triple-junction cells also have the
superstrate configuration with the structure composed of a-Si:H/μc-
Si:H/μc-Si:H (hereafter refered to as Triple A) and a-Si:H/a-Si:H/μc-
Si:H (hereafter refered to as Triple B) absorber layers. The detailed
deposition conditions and the characterization procedure for the
multijunction cells as carried out in our group are presented elsewhere