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±200 fA cm2 for nonpassivated emitters and of 490±120 fA cm2 for Al- p+ emitters passivated with a 20 nm thick amorphous silicon layer deposited at 225 °C. An additional annealing step at 300 °C for 10 min reduces the emitter saturation current density down to only 246±60 fA cm2. The measured saturation current densities are the lowest values achieved so far for Al-doped p+ emitter. © 2007 American Institute of Physics.