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Radial heteroemitter solar cells based on VLS grown silicon nanowires

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Abstract

Silicon nanowires (SiNWs) are an interesting system for the realization of solar cells, as they offer an enhanced light absorption compared to bulk Si. However, due to their large surface, nanowire solar cells suffer from high surface recombination which results in small carrier lifetimes. They therefore need perfect passivation. The use of an amorphous silicon heteroemitter on such structures enables a good surface passivation and therefore enables a higher open circuit voltage (VOC) than in crystalline core–shell structures. In this paper, we present the realization of radial junction SiNW solar cells by the vapor–liquid–solid (VLS) growth of n-doped SiNWs and subsequent coating by amorphous silicon in a PECVD process. The cells were contacted using atomic layer deposition of a transparent conductive oxide (aluminum-doped zinc oxide) as a front contact. The results of the SiNW solar cells are compared to a planar device to exclude the influence of the supporting wafer structure. The onset presented in this paper can possibly be used to realize SiNW based solar cells on low cost materials, as VLS enables the growth of SiNWs on almost any kind of surfaces.

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