Analysis of Inverse Lifetime Curves of TaOx Electron-Selective Contacts for Si Solar Cells

摘要

The analysis of Auger-corrected inverse minoritycarrier lifetime as a function of excess carrier concentration can impart information about many crucial solar cell material properties including: emitter saturation current density (J_o), surface recombination velocity (SRV), Shockley-Read-Hall (SRH) recombination in the bulk, trap density, band bending, surface Fermi-level pinning, and bandgap narrowing. This work demonstrates TaO_x as a potential electron selective contact and passivation layer on silicon. Increasing TaO_x thickness reduces the measured upper limit of effective surface recombination velocity (S_eff,UL)_. The minimum S_eff,UL is 55 cm/s for CZ n-Si/ 30 nm TaO_x interfaces. S_eff,UL increases for Si / TaO_x / ITO structures due to unfavorable band bending.