Photoluminescence imaging of thin film silicon on glass

Photoluminescence (PL) imaging over a large area (4.5×4.5 cm2) is demonstrated on polycrystalline silicon thin films and solar cells on glass. PL imaging is a well-established technique for characterisation of silicon wafers and wafer-based solar cells, however its application to crystalline silicon thin films on glass was not possible due to low material quality and volume, and IR noise from the glass substrate. This paper reports methods to overcome these limitations, the design of a thin-film silicon PL imaging system, examples of PL images of silicon films at different processing stages and preliminary findings. It is demonstrated that the observed PL images qualitatively correlate with the silicon film crystal grain structure and quality.