Formation of highly aluminum-doped p-type silicon regions by in-line high-rate evaporation

Highly aluminum-doped p-type silicon regions are formed by in-line high-rate evaporation of aluminum. We deposit aluminum layers of 28 μm thickness at dynamic deposition rates of 20 μm×m/min on p-type silicon substrates. Due to the high substrate temperature of up to 770 °C during deposition an Al-doped p+ region is formed. Using the camera-based dynamic infrared lifetime mapping technique we measure emitter saturation current densities of 695±65 fA/cm2 for the fully metalized Al-p+ regions, which corresponds to an implied solar cell open-circuit voltage of 635±2 mV.