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Silicon Hetero Junction (SHJ) structures and ZnO:Al (AZO) were deposited completely by high throughput industrial inline CVD and PVD deposition systems, respectively. A design of experiment of the AZO deposition parameters was carried out, to find suitable AZO layers for the use in SHJ solar cells. A subsequential thermal treatment on the AZO layers was performed to investigate their performance in a solar cell production. Thin AZO layers with the lowest specific resistance of 0.69 10-3 Ωcm were achieved with low T annealing. The highest carrier mobility of 22 cm2 V-1 s-1 was reached with high temperature annealing.

The present work demonstrates the suitability of spectral ellipsometry (SE) to properly characterize ultra-thin (< 15nm) hydrogenated microcrystalline silicon (μc-Si:H) and its possible advantages over alternative methods, e.g. Raman spectroscopy. For very thin μc-Si the undesirable amorphous and void-rich initial incubation layer can make up a significant fraction of the actual film, thereby adversely affecting the effective electrical and optical film properties. Based on SE measurements and a suitable model to fit the experimental data, the strong material inhomogeneities induced by the incubation layer can be analyzed and accounted for. This allows for (i) the non-invasive determination of the μc-Si:H film thickness and crystalline volume fraction and (ii) the evaluation of the material density. Using this approach, the growth behavior of μc-Si:H on different surfaces, the influence of doping precursor gases and different deposition parameters has been determined. A strong dependence between the film thickness and its density has been observed as well as its correlation with the electrical and optical properties in silicon heterojunction (SHJ) structures. Additionally, a good monocrystalline silicon (c-Si) surface passivation and high selectivity for the extraction of charge carriers from the absorber into the Transparent Conductive Oxide (TCO) electrode using n-type μc-Si:H as front layer is being demonstrated by high open-circuit voltages of up to 730mV and good contacts to the TCO (both ITO and AZO). The approach described and demonstrated in this work provides a suitable tool to engineer the partially crystallized doped layers of SHJ cells with respect to their electrical and optical properties at a device relevant level.

The permanent deactivation called regeneration of light induced degradation in p-type Czochralski silicon solar cells is analyzed in this paper. Industrial solar cells were fabricated with varying hydrogen concentration in the silicon nitride anti-reflection layer but with an otherwise identical setup. They are subsequently degraded, annealed and regenerated by simultaneous illumination and heating. Measurements of cell parameters reveal the crucial effect of hydrogen on the regeneration.