RAPID THERMAL-PROCESSING OF HIGH-EFFICIENCY SILICON SOLAR-CELLS WITH CONTROLLED IN-SITU ANNEALING

Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid the rmal processing (RTP). These represent the highest reported efficienci es for solar cells processed with simultaneous front and back diffusio n with no conventional high-temperature furnace steps. Appropriate dif fusion temperature coupled with the added in-situ anneal resulted in s uitable minority-carrier lifetime and diffusion profiles for high-effi ciency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J(o)), however, this effect is material and base resistivity specific . PECVD antireflection (AR) coatings provided low reflectance and effi cient front surface and bulk defect passivation. Conventional cells fa bricated on FZ silicon by furnace diffusions and oxidations gave an ef ficiency of 18.8% due to greater short wavelength response and lower J (o).