Laser doping through anodic aluminium oxide silicon solar cell

• The final cell efficiency of laser-doped through AAO PERL cell as high as 652 mV while the original implied Voc was ~620 mV for all cells after SiNx deposition.
• laser doping through AAO layers can be performed without introducing any voids into the Si and form a local BSF ~5 µm into Si which is advantageous for PERL cell structure.
• Laser-doping through a B-doped AAO layer can introduce aluminium into silicon to at least 10 µm.

This paper reports on the use of AAO layers as a source of p-type dopants for laser doping processes that forms localised p+ regions on Si surfaces. Sheet resistances as low as 2 Ω/sq were demonstrated when a laser was used to scribe through a region of AAO using a speed of 500 mm/s and power of 9 W. Unlike laser-doping through spin-coated polyboron sources, it was shown that laser doping through AAO layers can be performed without introducing any voids into the Si and form a local BSF ~5 µm into Si which is advantageous for PERL cell structure. This co-doping process was used to fabricate rear-passivated cells with efficiencies of up to 19.9%. However, although the heavily-doped local p+ regions could reduce Rs to values as low as 0.54 Ω cm2, there was a penalty in terms of a high ideality factor in the Vmp –Voc voltage range which limited FFs to ~76%.