Partially Contacted Surfaces With Contact Size In The 1 Mu M Range For C-Si Perc Solar Cells

We examine the electrical benefits of creating contacts with sizes in the 1 mu m range on partially contacted surfaces for c-Si PERC/L solar cells. In such a design, a dielectric layer that provides surface passivation is periodically opened to create contacts. Analytical models demonstrate that small contacts in the 1 mu m range and separated by a few microns result in lower ohmic losses when compared to a typical contact configuration. In order to obtain a good surface passivation quality, surface recombination velocities below 10(3) cm/s are needed for the contacted area. From PC-1D simulations of a reference structure, a clear advantage for small contacts is deduced for surface recombination at the contacts in the 10(2)-10(5) cm/s range. Additionally, a fabrication process to achieve the desired contact configuration is described using Al2O3 and thermally grown SiO2 films. This process is based on colloidal lithography using polystyrene nanoparticles. For Al2O3 films, an incomplete contact opening is observed, while much more repeatable results are obtained for SiO2 films.