The effect of rapid thermal annealed seed layer on the epitaxial poly-Si thin film solar cell׳s structure quality and performance

•RTA for the seed layer can improve the electronic quality of seed layer.•RTA for the seed layer can reduce defect density in the epi-layer.•Epitaxial poly-Si solar cell performance is improved by RTA treated seed layer.•High RTA temperature slightly decreases blue response of EQE.

Epitaxial polycrystalline Si solar cell performance is directly related to the seed layer crystal quality. In order to achieve a good crystal template for epitaxial growth, rapid-thermal annealing was used to eliminate the intragrain defects in the seed layer. Rapid thermal annealing can effectively activate the dopants and improve seed layer electronic properties. The resulted epitaxial solar cell׳s efficiency increases from 3.46% to 4.42% by applying rapid thermal annealing at 950 °C on the seed layer. The improved solar cell performance is related to the reduced amount of microtwins and dislocations grown from the seed layer to the epi-layer by rapid thermal annealing for the seed layer. However, higher rapid-thermal annealing temperature slightly decreases seed layer׳s free carrier concentration and blue response of external quantum efficiency due to the possible B diffusion from partially melted glass to the emitter.