High Phosphorus-doped Seed Layer in Microcrystalline Silicon Oxide Front Contact Layers for Silicon Heterojunction Solar Cells

In this paper, we investigated the application of n-type hydrogenated microcrystalline silicon oxide (n-μcSiO
_x
:H) as the front surface field (FSF) to improve the shortcircuit current density (J
_SC
) of silicon heterojunction (SHJ) solar cells. The advantage of employing n-μc-SiO
_x
:H layer is due to its low optical absorption coefficient and tunable refractive index. However, the SHJ solar cell performance was otherwise limited by the amorphous oxygen alloyed silicon-based films which probably deteriorate the incubation stage of the n-μc-SiO
_x
:H layer. To reduce amorphous/microcrystalline mixture phase during the growth, we implemented high phosphorus-doped seed layer deposited prior to n-μc-SiO
_x
:H layer with refractive indices in the range of 2.7 to 2.9. Finally, optimization of the nμc-SiO
_x
:H layer led to a conversion efficiency of 23.9%, with J
_SC
of 39.1mA/cm
²
, open circuit voltage (V
_OC
) of 740mV, and fill factor (FF) of 82.6%.