Impurities in electron beam recrystallised silicon absorbers on glass

Electron beam recrystallised polycrystalline silicon films on float glass for the use as solar cell absorber are investigated. The silicon layer is deposited in a high rate PECVD process using trichlorosilane SiHCl3 and hydrogen H2 . The initial nanocrystalline layer is zone melted and recrystallised to a polycrystalline film using a line shaped electron beam assembly. The layer set up consists of a 20 m thick silicon layer on a sputtered tungsten film. To prevent balling up, the silicon is covered with silicon dioxide SiO2 . The amount of chlorine and hydrogen in the initial layer is in the order of 0.1 1at and is reduced by the zone melting recrystallisation ZMR to maximum value of 0.05at . The ZMR also leads to a more uniform concentration in depth due to a fast diffusivity in the silicon melt. Outgassing of the chlorine and hydrogen is observed during the ZMR by mass spectroscopy of the remaining gas atmosphere in the recrystallisation chamber. Keywords PECVD, Thin Film, Recrystallisatio