Field effect passivation of plasma oxidized SiOx layer on boron emitter surface by PECVD

An ultra thin surface passivation layer is essential to reduce the surface recombination and enhance the open circuit voltage for high efficiency crystalline silicon (c-Si) solar cells. In that, we developed charge injection controllable thin films of SiO
_X
and SiN
_X
layers by PECVD for surface passivation of boron emitter c-Si surface. The refractive index of the SiO
_X
/SiN
_X
stack was optimized by varying the SiH
₄
, NH
₃
and N
₂
O gas ratios. Lower D
_it
of 5 × 10
¹⁰
cm
^-2
eV
^-1
and high Q
_eff
of -1.71 × 10
¹¹
cm
^-2
was obtained for 10 nm thick SiO
_X
layer. The fabricated n-Si bifacial cell with insertion of 10 nm thick SiO
_X
layer archived efficiency (η) of 19.48 % with fill factor (FF) of 77.5 %, whereas the cell without SiO
_X
layer showed an η of 18.20 % with FF of 75.77.