Effective passivation of highly aluminum-doped p-type silicon surfaces using amorphous silicon

Abstract

Highly aluminum-doped p-type emitters prepared by screen printing on crystalline silicon wafers are effectively passivated by plasma-enhanced chemical-vapor deposited amorphous silicon layers. Using the photoconductance decay technique, the authors measure emitter saturation current densities of 800±200fA∕cm2 for nonpassivated emitters and of 490±120fA∕cm2 for Al-p+ emitters passivated with a 20nm thick amorphous silicon layer deposited at 225°C. An additional annealing step at 300°C for 10min reduces the emitter saturation current density down to only 246±60fA∕cm2. The measured saturation current densities are the lowest values achieved so far for Al-doped p+ emitter.