Single Crystalline Mesoporous Silicon Nanowires

Abstract

Porous semiconductors have garnered significant attention for their novel chemistry and potential applications as high surface area and optically active substrates [ 1-5 ]. Porous silicon in particular has long been studied for its potential applications in optoelectronics and sensing as a result of its light-emitting properties [ 6-10 ]. In addition, they can also serve as drug or gene delivery matrix because of their good biocompatibility [11][12] . Porous silicon is typically synthesized by applying a voltage bias to a silicon substrate immersed in an aqueous or ethanoic hydrofluoric acid (HF) solution. Surface and charge instabilities at the solid-solution interface are thought to nucleate pore formation, and accelerated etching of silicon at the pore tips propagates the voids into the substrate. The resulting pore networks and remaining silicon scaffold form the structure of porous silicon [ 13,14 ]. The synthetic method described in this study, on the other hand, relies on an electroless metal deposition process to provide the current flux necessary for porous silicon formation. Electroless metal deposition and subsequent sacrificial etching of the surrounding silicon lattice has been previously observed [ 15 ] and exploited to controllably etch arrays of silicon nanowires [ 16 ]. We have now found that it is possible to etch arrays of single-crystalline mesoporous silicon nanowires without the application of an external voltage.

Si-containing precursors for Si-based anode materials of Li-ion batteries: A review

“…Facile methods such as electroless etching [30][31][32][33][34][35][36][37][38][39][40][41] and electrochemical etching [42][43][44][45][46][47][48] are able to convert bulk silicon wafer into a porous structure with tunable pore size and porosity, which is called 'integral' porosity. For example, with an appropriately doped Si wafer, porous Si and Si nanowires can be synthesized in the presence of silver nitrate (AgNO3) in hydrofluoric acid (HF) etchant solution.…”

Silicon Nanowires and Related Nanostructures as Lithium-Ion Battery Anodes

“…This method has been widely studied for the synthesis of silicon nanowires starting from various types of silicon wafers with different doping levels and orientations, including lightly and highly doped p-type Si(100) and Si(111) wafers, lightly doped n-type Si(100) and Si(111) wafers and Si(110) and Si(113) wafers. [41][42][43][44][45][46][47][48][49][50][51][53][54][55][56][57][58] The metal-assisted chemical etching reactions can be classified into two types: one-step reaction and two-step reaction. Recent reports show that single crystalline porous silcion nanowires have been synthesized through both one-step and two-step reactions by adjusting the reaction conditions.…”

“…Recent reports show that single crystalline porous silcion nanowires have been synthesized through both one-step and two-step reactions by adjusting the reaction conditions. [41][42][43][44][45][46][47][48][49][50][51] Highly Doped p-type Si (100) Wafer 43 One-step chemical etching involves the immersion of clean p-type silicon substrates in an etchant solution containing 0.01-0.04 M AgNO 3 and 5 M HF. It was found that the surface morphology of the as-synthesized silicon nanowires was highly dependent on the resistivity of the original silicon wafers.…”

“…2,39,40 Recent reports of single crystalline porous silicon nanowires have combined these two features together and form both electrically and optically active silicon nanostructures. [41][42][43][44][45][46][47][48][49][50][51] The development of these multifunctional nanostructures may open new opportunities for a new generation of silicon based optoelectronics and photoelectrochemical devices. In this articles, we highlight recent progress in the synthesis of porous silicon nanowires, optical and electric properties, as well as their potential applications in the fields of energy and biology.…”

Effective antireflection properties of porous silicon nanowires for photovoltaic applications

“…Among the preparation methods for such nanostructures [11,12], metalassisted chemical etching is well-received as one of the viable technique to produce highly ordered Si nanostructure arrays, as this simple technique is effective and cost effective. Porous silicon nanowires (PSiNWs) prepared by metal-electroless etching technique (13,14) have been widely explored as an alternative top-down route for the fabrication of nanostructures that give visible light emission and good electronic transport properties [15,16]. In this paper, we study the morphology of PSiNWs and the optical properties of this nanostructures.…”