Multiple Nanowire Species Synthesized on a Single Chip by Selectively Addressable Horizontal Nanochannels

Abstract

The synthesis of horizontal porous anodic alumina (PAA) structures with individually addressable channel systems is demonstrated. This was achieved by developing a multicontact design of aluminum finger structures (two to five contacts) on silicon wafers. These aluminum contacts were electrically isolated from each other, allowing the individual anodization of each contact at different conditions. This way it is possible to synthesize different pore diameters, pore densities, and channel lengths on a single chip. Scanning electron microscopy (SEM) characterization revealed that the neighboring contacts are not significantly altered during the anodization procedure. After successful barrier-layer thinning, the individual finger structures of each contact were filled by electrodeposition and thermal chemical vapor deposition. The resulting metal (Au, Cu, Ni, Co) and semiconductor (Te, Si) nanowires embedded within the porous anodic alumina mold were characterized by SEM and energy dispersive X-ray measurements. The multicontact fabrication results open a new route toward complex nanoelectronic and sensing applications.

The Selective Growth of Silicon Nanowires and Their Optical Activation

“…They give easy access to self-organized pores with high aspect ratios and tunable pore sizes (Gao et al 2002;Masuda & Fukuda et al, 1995;Krishnan & Thompson, 2007;Nielsch et al, 2000). These pores are then used as a molding system for the synthesis of the desired nanostructures (Xiang et al, 2010). The VLS growth of SiNWs inside the pores of an unsupported PAA template using SiH 4 as the precursor gas has been completed (Bogart et al, 2005;Lew & Redwing, 2003;, as shown in Figure 1.12.…”

Mechanical constraint and release generates long, ordered horizontal pores in anodic alumina templates

“…Recently, other groups have realised similar horizontally-oriented nanochannels following this idea. [16][17][18][19] In these reports, an aluminium film deposited onto an oxidised silicon substrate was etched in parallel strips and then capped with a silicon oxide layer. [16][17][18][19] The short edges of the strips were dipped into the electrolyte and the anodisation proceeded along their lengths.…”

“…[16][17][18][19] In these reports, an aluminium film deposited onto an oxidised silicon substrate was etched in parallel strips and then capped with a silicon oxide layer. [16][17][18][19] The short edges of the strips were dipped into the electrolyte and the anodisation proceeded along their lengths. Cojocaru and coworkers [17] have shown scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of horizontal pores, 200-300 nm long, with pore diameters between 3-4 nm.…”

“…Xiang et al included a growth rate but no physical characterisation of pore length, morphology or ordering as a function of length. [19] An exhaustive study regarding in plane pore growth of confined Al fingers, including pore length and direction/orientation, morphology and ordering of pores, as a function of length, is therefore still required. Such a characterisation study will provide insight into the fundamental processes governing AAO pore formation in a constrained environment and enable subsequent exploitation of the governing factors to prepare highly ordered, long, planar oriented AAO, which has not yet been reported.…”

Optimization of organized silicon nanowires growth inside porous anodic alumina template using hot wire chemical vapor deposition process

“…Since then, such structure, usually called Porous Anodic Alumina (PAA) membrane, has been widely used in the field of nanowires/nanotubes growth because of its easilycontrollable features, and the high aspect ratio of the pores [7,8,9,10,11]. Despite this progress, SiNWs growth still lacks a good control and understanding of the mechanisms that rule their formation [5,12,13,14], especially in such a very particular case where a confined growth occurs.…”