Silicon solar cell efficiencies of 16.9% have been achieved on 0.2 OME
GA cm float zone silicon, using a simplified cost effective rapid ther
mal process (RTP). Although the individual processing steps are not fu
lly optimized yet, this represents the highest reported efficiency for
solar cells processed with simultaneous front and back diffusion with
no conventional high-temperature furnace steps. A diffusion temperatu
re schedule coupled with an added short in situ slow cooling during RT
P resulted in greater than 200 mum diffusion length and appropriate di
ffusion profiles for high efficiency cells. Plasma enhanced chemical v
apor deposition (PECVD) of SiN/SiO2 was used for surface passivation a
nd antireflection coating. Conventional cells fabricated by furnace di
ffusions and oxidations gave an efficiency of 18.8%. Process optimizat
ion can further reduce the gap between the conventional and RTP/PECVD
cells. (C) 1994 American Institute of Physics.