Tunneling or Pinholes: Understanding the Transport Mechanisms in SiO_x Based Passivated Contacts for High-Efficiency Silicon Solar Cells

摘要

We have compared the temperature dependence of the poly-Si/SiO_x/c-Si contact performance for 1.5 and 2.2 nm thick SiO_x. The optimum annealing temperature for these two is different, likely due to the SiO_x influencing the extent of dopant diffusion into c-Si. At 1050 °C, while a contact with 1.5 nm SiO_x significantly breaks up, the one with 2.2 nm SiO_x develops pinholes. Using scanning Kelvin probe microscopy, we demonstrate that there is enhanced dopant diffusion through these pinholes. Finally, using electron-beam induced current measurements, we show that pinholes affect the local passivation quality of the c-Si wafer surface.