TiO2 / p-Si paste heterojunction fabricated by rapid thermal annealing

Abstract TiO2/p-Si paste heterojunction structure, which showed photovoltaic characteristics, was successfully fabricated by rapid thermal annealing (RTA). To reduce the oxidation of Si paste during the RTA, Ti was sputtered on the p-type Si paste. It was found that the RTA condition of 1200 °C/2 s enabled the Si paste to achieve the lowest oxidation and the best crystallization conditions, as well as the transformation of the Ti layer into the rutile TiO2 phase. It was observed that some molten Si grain lumps appeared on the surface of the sample annealed at 1200 °C for 2 s. This phenomenon was due to the melting process of the surface Si particles promoted by the Ti layer. Typical rectifying characteristics and photocurrent density of 36 μA/cm2 under AM1.5 were observed with the TiO2/p-Si paste heterojunction device annealed at 1200 °C for 2 s. This study shows an application potential of Si paste films for such devices as future solar cell.