Microcrystalline Silicon Solar Cells: Effect of Substrate Temperature on Cracks

Single junction microcrystalline silicon solar cells presently reach confirmed efficiencies up to 10.1%. Further improvement on device quality is now necessary to continuously increase the electrical performances of the solar cells. Zones of porous material, called “cracks”, appear when the substrate, such as glass covered with zinc oxide (ZnO), is too “rough”. Previous works have demonstrated that these cracks have mainly detrimental effects on the Fill Factor (FF), and act as bad diodes with a high reverse saturation current. The number of cracks can be decreased with appropriate surface treatment, but then, the light scattering is reduced (lower roughness). This study presents an alternative/complementary way to decrease crack density by increasing the substrate temperature during deposition, which leads to an increase of FF.