High-efficiency OECO Czochralski-silicon solar cells for mass production

To improve the economy of photovoltaics, efficiencies of solar cells have to be drastically increased without using complex technologies. This work demonstrates that with the obliquely evaporated contact metal-insulator-semiconductor (MIS)-n+p solar cell structure recently developed at ISFH efficiencies exceeding 21% can be obtained using only four simple fabrication steps: (i) mechanical surface grooving, (ii) P-diffusion, (iii) oblique vacuum evaporation of Al, and (iv) plasma silicon nitride deposition. Cell design and processing sequences are outlined together with the importance of MIS contacts as both low-cost and high efficiency features. The custom-made pilot line equipment for mass production of 20% efficient 10×10 cm2 Cz silicon solar cells including Ga doped wafers is described.