Effect of c-Si doping density on heterojunction with intrinsic thin layer (HIT) radial junction solar cells

Radial junction Si pillar array solar cells based on the heterojunction with intrinsic thin layer (HIT) structure were fabricated from p-type crystal Si (c-Si) wafers of different doping densities. The HIT structure consisting of intrinsic/n-type hydrogenated amorphous Si (a-Si:H) deposited by plasma-enhanced chemical vapor deposition (PECVD) at low temperature (200°C) was found to effectively passivate the high surface area of the p-type Si pillar arrays resulting in open circuit voltages (V_oc>0.5) comparable to that obtained on planar devices. At high c-Si doping densities (>10¹⁸ cm^-3), the short-circuit current density (J_sc) and energy conversion efficiency of the radial junction devices were higher than those of the planar devices demonstrating improved carrier collection in the radial junction structure.