The effect of hydrogenated amorphous silicon (a-Si:H) intrinsic layers, deposited on boron-doped multicrystalline silicon (mc-Si) wafers at various deposition temperatures, on heterojunction solar cells prepared using the radio-frequency remote PECVD method are investigated. The structural and optical properties of the a-Si:H films formed at various deposition temperatures that ranged from 50 to 400°C changed with increasing temperature. The effective carrier lifetimes of the mc-Si wafers with the a-Si:H films increased with increasing deposition temperature to a maximum of 250°C. Furthermore, the wafers passivated with the a-Si:H films deposited temperatures below 250°C, and the effective carrier lifetime drastically improved to about 2-5 times its as-deposited value and over the chemical passivation lifetime after annealing treatment at 350°C. It was found that a combination of a-Si:H film deposition and annealing treatment provides excellent bulk passivation. [DOI: 10.1380/ejssnt.2008.124]