Film properties of alumina passivation layer for silicon solar cells prepared by spin-coating method

We prepared alumina passivation films deposited by a sol-gel wet process for silicon substrates. Aluminum acetylacetonate was used as a precursor, and the solution was spin-coated onto silicon substrates. Calcination temperature dependence of the passivation quality of the films was evaluated mainly by measuring effective lifetime using a photo conductance decay technique and capacitance-voltage measurements. Also, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were carried out to evaluate film properties. A large amount of negative fixed charge density (Qf = − 3.1 × 1012 cm− 2) exists in the films calcined at 300 °C. On the other hand, a long effective lifetime of 400 μs was obtained for the sample calcined at 600 °C, and the passivation films had a large amount of positive fixed charge density (Qf = 3.6 × 1012 cm− 2) with a low interface state density.