Surface Passivation and Simulated Performance of Solar Cells With Al $_{\bf 2}$O$_{\bf 3}$/SiN $_{\bm x}$ Rear Dielectric Stacks

Al
₂
O
₃
/SiN
_x
stacks that are prepared at low temperatures in chemical vapor deposition processes excel in terms of surface passivation applicable in industrial p-type Si solar cells. The conversion efficiencies that are feasible for solar cells with Al
₂
O
₃
/SiN
_x
rear dielectric stacks, have been investigated by numerical simulations, including the optical performance of the stacks, which was considered for various Al
₂
O
₃
and SiN
x
film thicknesses. The optically optimized film thicknesses were found to be 15-30 nm for Al
₂
O
₃
and 100-120 nm for the SiN
_x
films. Experimentally, the surface passivation was found to be similar for annealed Al
₂
O
₃
/SiN
_x
stacks and single-layer Al
₂
O
₃
films with an almost equal level of field-effect and chemical passivation, as determined by optical second harmonic generation and corona charging experiments.