This paper analyzes the impact of femtosecond laser pulse irradiation on the crystallinity of silicon wafers by means of electron backscatter diffraction (EBSD) measurements. EBSD based image quality maps and orientation imaging microscopy maps are correlated to the grade of the silicon crystallinity. We analyze the impact of accumulated net laser irradiation originating from a laser spot overlap that is necessary to process macroscopic areas, e.g., for sulfur doping of semiconductor devices. Furthermore, we demonstrate that post processing annealing recovers crystallinity and therefore allows fs-laser processed silicon to be used in semiconductor device manufacturing
We fabricated an efficient hybrid solar cell by spin coating poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) on planar multicrystalline Si (mc-Si) thin films. The only 5 μm thin Si absorber layers were prepared by diode laser crystallization of amorphous Si deposited by electron beam evaporation on glass. On these absorber layers, we studied the effect of SiOx and Al2O3 terminated Si surfaces. The short circuit density and power conversion efficiency (PCE) of the mc-Si/Al2O3/PEDOT:PSS solar cell increase from 20.6 to 25.4 mA/cm2 and from 7.3% to 10.3%, respectively, as compared to the mc-Si/SiOx/PEDOT:PSS cell. Al2O3 lowers the interface recombination and improves the adhesion of the polymer film on the hydrophobic mc-Si thin film. Open circuit voltages up to 604 mV were reached. This study demonstrates the highest PCE so far of a hybrid solar cell with a planar thin film Si absorber.
In this paper, we demonstrate a two‐step laser crystallization process for thin film silicon solar cells on glass. In a first step a 5 µm thick amorphous silicon layer is crystallized by a diode laser to get the absorber. The multicrystalline layer consists of grains with sizes in the range of 1 mm to 10 mm. In a second step a thin amorphous silicon layer is epitaxially crystallized by an excimer laser to form the emitter.Epitaxy was investigated in a fluence range of 700 to 1200 mJ/cm2. The resulting thickness of the emitter is measured and numerically simulated, both resulting in 185 nm for a fluence of 1100 mJ/cm2. The solar cells achieve maximum open circuit voltages of 548 mV, short‐circuit current densities of up to 22.0 mA/cm2 and an efficiency of 8.0%.
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