Abstract
In this paper, we study the impact of change in emitter diffusion profiles on the electrical characteristics of nanotextured surfaces formed by an inline plasma-less dry-chemical etching process. Our experimental results and process simulations suggest that a deeper highly doped region and a significantly higher inactive P concentration in the emitter plays a determining role in defining recombination, as well as the resistive losses in nanotextured surfaces. Low emitter saturation current densities on phosphorous-diffused surfaces are achievable after passivation with either SiNx (j0e,m in ≈ 81 fA/cm2) or AlOx/SiNx (j0e,m in ≈ 31 fA/cm2) if the emitter recombination channels are suppressed. Based upon macroscopic measurement of contact resistivity and microscopic analysis of the contact areas, we propose that the formation of numerous metal-semiconductor direct contact points on the peak and the plateaus of the nanostructures are mainly responsible for a low specific contact resistivity (ρc,m in ≈ 1.2 mΩ · cm2) achievable in these surfaces.