Sputtering - a key technology for thin film deposition in crystalline silicon solar cell production?

The novel sputter source TwinMag is used to deposit silicon nitride as an antire flection layer for crystalline silicon solar cells. TwinMag consists of two pl anar magnetrons, standing side by side and supplied with MF-power. The source is developed for large area coating and is able to deposit metal oxides and nitr ides with high deposition rates. The characteristics of sputtered silicon nitri de films have been investigated in respect to solar cell technology. First sol ar cells have been processed using TwinMag sputtered silicon nitride as an ant i-reflection coating and simple industrial like processes. These cells yield eff iciencies of up to 13.2% on 2x2 cm² multi-crystalline and 15.6% on 10x10 cm² m ono-crystalline silicon and a corresponding open circuit voltage of up to 595 mV and 611 mV, respectively. These results imply that severe emitter damage does not occur due to the sputtering process. Also good optical characteristics have been found for the used layer. Surface recombination velocities below 1000 cm /s are deduced from lifetime measurements. The very high bond density of the s puttered films being measured by FTIR spectrometry demonstrates their high quali ty. Adding molecular hydrogen to the process a high content of up to 3x1022 h ydrogen atoms/cm3 could be determined. These results indicate, that high quality surface passivation should also be possible for sputtered silcion nitride films.