A review on plasma-assisted VLS synthesis of silicon nanowires and radial junction solar cells

Abstract

We use a metal assisted chemical etch process to fabricate silicon nanowire arrays (SiNWAs) onto a dense periodic array of pyramids that are formed using an alkaline etch masked with an oxide layer. The hybrid micro-nano structure acts as an anti-reflective coating with experimental reflectivity below 1% over the visible and near-infrared spectral regions. This represents an improvement of up to 11 and 14 times compared to the pyramid array and SiNWAs on bulk, respectively. In addition to the experimental work, we optically simulate the hybrid structure using a commercial finite difference time domain package. The results of the optical simulations support our experimental work, illustrating a reduced reflectivity in the hybrid structure. The nanowire array increases the absorbed carrier density within the pyramid by providing a guided transition of the refractive index along the light path from air into the silicon. Furthermore, electrical simulations which take into account surface and Auger recombination show an efficiency increase for the hybrid structure of 56% over bulk, 11% over pyramid array and 8.5% over SiNWAs.

Synthesis of silicon oxide nanowires by the GJ EBP CVD method using different diluent gases

“…Their use for the manufacture of SCs is a natural step in the development of methods for texturing thin-film SCs [4,5]. Nanowires of silicon, ZnO, CdSe, InP, and GaAs [5][6][7][8][9] or, more precisely, aligned, ordered, or disordered arrays of nanowires of these materials fit this purpose. They are used to produce SCs with axial [8] or radial junctions [5][6][7]9].…”

Birth of silicon nanowires covered with protective insulating blanket

“…This is useful in removing the surface oxide of SnONPs that mediate the adsorption of Si atoms into SnONPs. [12,14,15] In our experiments failing H 2 plasma, the growth of NWs is not observed due to inefficiency of Si adsorption posed by the surface oxide layer. It is worth mentioning that H 2 plasma helps in the formation of SnONPs and the reduction of the surface oxide layer caused due to the minimization of the energy.…”

“…Nevertheless, until now, these methods are used either to produce SiNWs, SiO x NWs or silica NWs. [3,[11][12][13] This work demonstrates the growth of Si-SiO x NWs simultaneously without additional process steps in large quantities, which are uniform, well defined, and better aligned. This process does not pose problems associated with non-conformal coating due to the shadowing of NWs and allows the optimization and controlled growth with a mature and already available PECVD technique at low temperatures (300°C).…”

“…Conversely, few thin NWs are observed without a shell for NWs grown from SnAcAc along with core-shell NWs that could arise from formation of tiny Sn NPs from complete dissociation of organic molecules attached to Sn atoms. However, the nucleation, supersaturation, and precipitation of Si atoms in metal NPs such as indium, tin, gold, bismuth, and gallium and many more metals are explained and thoroughly studied by many researchers, [12] whose underlying principle is based on the eutectic temperature, the morphology of catalyst, the equilibrium solubility concentration, surface tension, sidewall wetting by catalyst, and the fabrication procedure involved during growth process. In contrast, the core-shell NWs grown here are different with the use of metal-oxide NPs (MONPs) that are used for nucleation and precipitation.…”

Toward Efficient Radial Junction Silicon Nanowire‐Based Solar Mini‐Modules

“…However, thinning down the absorber layer will reduce light absorption, hence potentially limiting the performance of solar cells. Therefore, sophisticated nanotechnology approaches for advanced light trapping have been realized to improve the light trapping, including nanotubes, nanopillars, and nanowires (NWs) . In particular, NWs have gained attention due to the ability to deposit solar cells on top of them and achieving a very good performance with ultra‐thin absorbing layers .…”