Broadband transparent conductive oxide layers with high electron mobility (μ_e) are essential to further enhance crystalline silicon (c-Si) solar cell performances. Although metallic cation-doped In₂O₃ thin films with high μ_e (>60 cm² V^-1 s^-1) have been extensively investigated, the research regarding anion doping is still under development. In particular, fluorine-doped indium oxide (IFO) shows promising optoelectrical properties; however, they have not been tested on c-Si solar cells with passivating contacts. Here, we investigate the properties of hydrogenated IFO (IFO:H) films processed at low substrate temperature and power density by varying the water vapor pressure during deposition. The optimized IFO:H shows a remarkably high μ_e of 87 cm² V^-1 s^-1, a carrier density of 1.2 × 10²⁰ cm^-3, and resistivity of 6.2 × 10^-4 ω cm. Then, we analyzed the compositional, structural, and optoelectrical properties of the optimal IFO:H film. The high quality of the layer was confirmed by the low Urbach energy of 197 meV, compared to 444 meV obtained on the reference indium tin oxide. We implemented IFO:H into different front/back-contacted solar cells with passivating contacts processed at high and low temperatures, obtaining a significant short-circuit current gain of 1.53 mA cm^-2. The best solar cell shows a conversion efficiency of 21.1%.

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A study is presented giving the response of three types of fiber-optic interferometers by which a standing wave through an object is investigated. The three types are a Sagnac, Mach¿Zehnder and Michelson¿Morley interferometer. The response of the Mach¿Zehnder interferometer is similar to the Sagnac interferometer. However, the Sagnac interferometer is much harder to study because of the fact that one input port and output port coincide. Further, the Mach¿Zehnder interferometer has the advantage that the output ports are symmetric, reducing the systematic effects. Examples of standing wave light absorption in several simple objects are given. Attention is drawn to the influence of standing waves in fiber-optic interferometers with weak-absorbing layers incorporated. A method is described for how these can be theoretically analyzed and experimentally measured. Further experiments are needed for a thorough comparison between theory and experiment.@en

Positron annihilation depth profiling is applied as a sensitive probe to investigate the defect evolution of hydrogenated amorphous silicon (a-Si:H) absorber layers fabricated by the PE-CVD method with typical thicknesses of 300-500 nm. The Doppler broadening lineshape parameter S of the layers was found to depend significantly on the applied hydrogen-to-silane flow ratio during their deposition, related to hydrogen-induced changes in the microstructure and local composition at the positron trapping site. Light-soaking degradation induces a time-dependent variation in the S parameter which seems to correlate with the evolution of defect densities extracted from FT-Photocurrent Spectroscopy measurements.@en