Fabrication of slantingly-aligned silicon nanowire arrays for solar cell applications

Abstract

Large-area slantingly-aligned silicon nanowire arrays (SA-SiNW arrays) on Si(111) substrate have been fabricated by wet chemical etching with dry metal deposition method and employed in the fabrication of solar cells for the first time. The formation of SA-SiNW arrays possibly results from the anisotropic etching of silicon by silver catalysts. Superior to the previous cells fabricated with vertically-aligned silicon nanowire arrays (VA-SiNW arrays), the SA-SiNW array solar cells exhibit a highest power conversion efficiency of 11.37%. The improved device performance is attributed to the integration of the excellent anti-reflection property of the arrays and the better electrical contact of the cell as a result of the special slantingly-aligned structure. The high surface recombination velocity of minority carriers in SiNW arrays is still the main limitation on cell performance.

Nanostructured Inorganic Solar Cells

“…Similar nanowire lengths and diameters can be produced. In work by Fang et al, slanted NW arrays were created, which was attributed to anisotropic etching of the Si underneath the metal clusters, and to competition between different etching directions [30]. Figure 6 (d) displays a SEM cross-section of a slantingly-aligned Si NW array created by MCEE of a Si substrate in a HF=H 2 O 2 =H 2 O solution [30].…”

“…In different etching solutions, the Si substrate can instead be dissolved at the location of the deposited Ag species, as shown in Figure 6 (c) [30,35]. Similar nanowire lengths and diameters can be produced.…”

Silicon-Based Third Generation Photovoltaics

“…Basically, a noble metal is deposited on the surface in the form of nanoparticles which act as catalyst for Si etching in HF solution containing an oxidizing agent. As a consequence, the etching only occurs in the vicinity of the metal nanoparticles and results in the formation of well defined mesopores (20-100 nm in diameter (Fang et al, 2008) (Peng et al, 2005) (Fig. 27 (a)).…”

“…In the radial case the pn junction covers the whole outer cylindrical surface of the NWs. This was achieved either by gas doping or by CVD deposition of a shell oppositely doped to the wire (Fang, 2008) (Peng, 2005) (Tian 2007). In the axial variant, the p-n junction cuts the NW in two cylindrical parts and require minimal processing steps (Andra 2008).…”

“…By using VLS method (Tian et al, 2007) (Kelzenberg et al, 2008) (Rout et al, 2008) (Fang et al, 2008) (Perraud et al, 2009) as well as by the etching method (Garnett et al, 2008) (Peng et al, 2005). SiNW based photovoltaic devices were experimentally demonstrated.…”