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Enhanced photovoltaic performance of vapor–liquid–solid grown silicon nanowire array with radial heterojunction



We present the fabrication of a vapor–liquid–solid grown silicon nanowire array solar cell with a radial heterojunction. Lithography defined Cu catalyst patterning is used to grow a periodic array of 300 nm diameter nanowires with a center-to-center distance of 800 nm. A conformal a-Si:H layer is deposited on the nanowire surface to create the heterojunction and passivate the nanowire surface. Transparent conductive oxide and Ni–Al metal grid are then deposited to complete the solar cell fabrication. With a nanowire height of 1.6 µm, the solar cell has an open-circuit voltage of 467 mV. This clear improvement of the open-circuit voltage compared to previous works may be due to the conformal deposition of a-Si:H and to the use of a Cu catalyst. The parameters limiting the solar cell performances are discussed and explained. This work opens up the possibility to fabricate silicon nanowire array solar cells on low-cost substrates.