ABSTRACT
Contact (TEC) structures were utilized in design and fabrication of NPS/poly-Si solar cells, aiming to reduce the series resistance and enhance the conversion efficiency of devices.
2 EXPERIMENTAL
To prepare NPS layers, n+-type poly-Si surface layers were firstly formed on p-type poly-Si wafers by an iterative-diffusion doping technique using POCL:O2 at 850oC. Then NPS films were prepared on the heavily-doped n+-poly-Si layers by an anodic etching process. The anodization was carried out under etching parameters of HF:C2H5OH:H2O = 18:1:1 at a current density of 5 mA/cm2 for 2 min. Thereafter, inter-digitated trenched structures were formed in the NPS layers by a RIE process through a metal mask. Finally, by using the same mask, Cr/Al metals were deposited onto the trenches by e-beam evaporation to construct the TEC structures.
