Boron diffused emitters passivated with Al2O3 films

In this work we study the fabrication and characterization of boron diffused emitters using FZ c-Si(n) substrates. Emitter surface was passivated with Al
₂
O
₃
(25 nm thick) layers deposited by thermal atomic layer deposition ALD technique. This study covers a broad emitter sheet resistance R
_sh
range from 20 to 250 Ω/sq using both polished and textured wafers. Emitter electrical quality was tested by means of lifetime measurements using quasi-stationary photoconductance QSS-PC method. Dark saturation emitter current densities Joe's were extracted from lifetime measurements resulting in Joe's values ranging from 10 to 150 fA/cm
²
depending on R
_sh
. These results are in the-state-of-the-art in boron emitter passivation.