Fabrication and characterization of SiC-based transparent passivating contacts for enhanced photovoltaic performance

Abstract

Silicon Carbide (SiC) passivating contacts are thought to be an emerging solution to bridge the existing gap in the silicon-based solar market. Passivating contacts directly tackle the intrinsic metal-semiconductor interfaces issues like recombination losses and Fermi-level pinning. Considering this approach, SiC-based Transparent Passivating Contacts (TPC) are fabricated on n-Si <100> using RF magnetron sputtering at multiple RF powers for enhanced solar cell performance. All said contacts were convolved through a variety of optical, and electrical techniques. It is confirmed that the passivating contacts grown by higher RF power have an enhanced provision for both transmission and contact passivation. Additionally, it has been found that a sufficient amount of oxygen vacancies (VO) are located at the SiC/Si interface and are mainly responsible for limiting of the contact passivation. This issue might be resolved by opting for larger RF power during the SiC growth that may suppress VO impact. Further, purely optical and electro-optical parameters and their dependence on VO have been readily studied. Most importantly the extent of contact passivation has been readily measured by the transient of photo voltages and Q-DLTS techniques and cross-verified by current kinetics studies. It is found by the current-voltage and energy band picture that the SiC grown at higher RF would provide better contact passivation with surface resistance of ∼109 Ω and positive trap centers, respectively.