Silicon nanowire solar cells grown by PECVD

Silicon nanowires offer an opportunity to improve light trapping in low-cost silicon photovoltaic cells. We have grown radial junctions of hydrogenated amorphous silicon over p-doped crystalline silicon nanowires in a single pump-down plasma enhanced chemical vapor deposition process on glass substrates. By using Sn catalysts and boosting p-type doping in the nanowires, the open-circuit voltage of the devices increased from 200 to 800 mV. Light trapping was optimized by extending the length of nanowires in these devices from 1 to 3 μm, producing currents in excess of – 13 mA cm− 2 and energy conversion efficiencies of 5.6%. The advantages of using thinner window layers to increase blue spectral response were also assessed.

► SiNW solar cells were grown on glass using standard a-Si:H deposition techniques.
► Energy conversion efficiencies of 5.6% were achieved.
► Approaches to reduce voltage losses in VLS-grown SiNW cells are discussed.
► SiNW length was optimized to maximize light trapping and short-circuit current.
► Approaches to boost spectral response in the blue are discussed.