N-Type Polycrystalline Silicon Thin Films and Solar Cells Deposited by CVD

Abstract

We deposit n+ polycrystalline silicon (pc-Si) thin films on glass substrates by atmospheric pressure CVD, using trichlorosilane as a Si source and PCl3 as a phosphorous source. The structural and electrical characterization of the films, involving measurements of X-rays diffraction, reflectance in the UV region, SEM microscopy, electrical conductivity as a function of temperature and Hall effect, reveal a material suitable to act as emitter in a solar cell. To prove the concept we deposit c-Si (p) / pc-Si (n+) junctions, and we characterize them by measurements of the I-V curve and the quantum efficiency. Despite a high series resistance, which degrades the fill factor, the cells show high values of open circuit voltage (~500 mV) and short circuit current (~25 mA/cm2), and a wide spectral response. The results are encouraging for the deposition of low-cost polycrystalline thin film silicon solar cells on glass by CVD.