Array density effect on the optical and photoelectric properties of silicon nanowire arrays via Ag-assisted chemical etching

Abstract

Ag-assisted chemical etching (AgACE) is a low-cost method to produce silicon nanowires (SiNWs) for photoelectric applications. Structure parameters of SiNWs have great impact on their optical and photoelectric properties, which are worth studying for fabricating high-performance devices. However, array density of SiNWs via AgACE, as an important structural parameter, has not been sufficiently investigated. Here, array density effect on the optical and photoelectric properties of SiNWs is experimentally investigated. SiNW arrays with different densities (silicon occupation ratio of 7%–34.5%) were prepared through controlling the reaction time of silicon wafers in the seed solution (t seed). The SiNW array with a t seed of 90 s shows optimum light absorption over 98% in the wavelength range of 300–1000 nm, though all the samples have light absorption over 95% due to the light trapping effect of nanowire array structure. In addition, the SiNW array with a t seed of 90 s exhibits the best photoelectric property. SiNW arrays with shorter t seed and higher density suffer more surface recombination, harming the photoelectric property. In SiNW arrays with longer t seed than 90 s and lower density, some SiNWs topple down and break, which has an adverse effect on transport and collection of carriers. These results indicate that the array density of SiNWs via AgACE has obvious effect on their photoelectric property. SiNW arrays via AgACE with a t seed of 90 s are ideal for photoelectric devices. This work is potential to guide SiNW fabrication for photoelectric applications.