The high quality of the AAO obtained makes it very promising for nanofabrication. Silicon nanowires Silicon nanowire (NW) arrays are widely studied nowadays because of their potential applications in microelectronics or detectors. Among the fabrication techniques, CVD is favoured. However, conventional techniques do not allow a good control on the position nor the homogeneity of the wires. Highly organised porous ITF2357 molecular weight alumina has been successfully used

as a template for the catalytic CVD growth of defect-free array of Si NW. For this, alumina is build on a <100> Si conductive wafer as described previously. Mould and anodization characteristics are adapted to the desired diameters, period and thickness of the future Si NW arrays. Energy dispersive X-ray analysis was performed on the cross section of the NW array before removal of the alumina template. High voltage of the electron

beam of an GDC-0449 molecular weight ultra-Zeiss SEM was settled at 5 kV, and the sample was positioned at a working distance (WD) of 7 mm. Atoms of aluminium, oxygen, gold and silicon were mapped. Figure 3a,b,c,d,e shows the map of these atoms, and an intensity profile of Si, Al and O atoms is presented in Figure 3f. As expected, silicon is present in the template’s pores, the template is composed of aluminium and oxygen, and gold is present at the upper end of the silicon wires. click here Figure 3 Energy dispersive X-ray (EDX) analysis of Si NW. (a) SEM image of the cross section, (b) aluminium cartography, (c) oxygen cartography, nearly (d) silicon cartography, (e) gold cartography and (f) profile counts of oxygen, aluminium and silicon, along the arrow of (a). The EDX analyses were conducted at 5-kV high voltage

and for a 7-mm WD. Top view of silicon wires are reported in Figure 4a, showing a good filling rate around 80%. Different periods and diameters for the NWs are shown in Figure 4b,c,d,e, before or after the removal of the catalyst. One can notice the very good quality of the triangular lattice as well as the smooth cylindrical surface of the wires. On the foreground of Figure 4b, a few disordered wires have grown above the hexagonal array. Those wires are due to gold droplet coalescence above the alumina array. Indeed, when the wires reach the top surface of the alumina template, the gold droplets coalesce and nanowires with a bigger diameter grow above the array. As the <111> direction is the prefer orientation for NW growth [35] and because the growing conditions widely change outside the alumina, these nanowire kink with an angle of 54.7°. Besides, according to the homogeneity of the catalyst deposition, a difference in the speed of growth of the wires can be observed over the substrate between wires. It leads to small differences in the wires’ height, as shown in Figure 4d.