Abstract
Periodically ordered arrays of vertically aligned Si nanowires (Si NWs) are successfully fabricated by nanosphere lithography combined with metal-assisted chemical etching. By adjusting the etching time, both the nanowires’ diameter and length can be well controlled. The conductive properties of such Si NWs and particularly their size dependence are investigated by conductive atomic force microscopy (CAFM) on individual nanowires. The results indicate that the conductance of Si NWs is greatly relevant to their diameter and length. Si NWs with smaller diameters and shorter lengths exhibit better conductive properties. Together with the I–V curve characterization, a possible mechanism is supposed with the viewpoint of size-dependent Schottky barrier height, which is further verified by the electrostatic force microscopy (EFM) measurements. This study also suggests that CAFM can act as an effective means to explore the size (or other parameters) dependence of conductive properties on individual nanostructures, which should be essential for both fabrication optimization and potential applications of nanostructures.
Highlights
Silicon nanowires (Si Si nanowires (NWs)) have gained promising applications in electronic, photonic, optoelectronic and many other fields due to their high aspect ratio and unique electrical, thermoelectric and photoelectrical properties, as well as the compatibility with traditional silicon technology [1– 5]
Our study reveals the sizedependent properties of Si NWs and suggests that conductive atomic force microscopy (CAFM) can act as an effective means to explore the size dependence of conductive properties on individual nanostructures
By changing the Reactive ion etching (RIE) time, the diameter of polystyrene spheres (PS) spheres can be reduced to desired values, and Si NWs with controllable diameters can be achieved
Summary
Silicon nanowires (Si NWs) have gained promising applications in electronic, photonic, optoelectronic and many other fields due to their high aspect ratio and unique electrical, thermoelectric and photoelectrical properties, as well as the compatibility with traditional silicon technology [1– 5]. Many methods have been developed to prepare Si NWs, including bottom-up methods such as vaporliquid-solid method, chemical vapor deposition, and molecular beam epitaxy [6–10] and top-down approaches using electron-beam lithography, reactive ion etching or metal-assisted chemical etching [11–16]. Among these methods, nanosphere lithography (NSL) combined with metal-assisted chemical etching (MACE) has been intensively adopted to fabricate large-area ordered arrays of vertically aligned Si NWs for its simplicity, low cost, and versatility [15–23]. In recent decades, scanning probe microscopy (SPM)based electrical measurements reveal themselves as powerful techniques for electrical characterizations at nanoscale [29, 30] Among these SPM techniques, conductive atomic force microscopy (CAFM) has been successfully applied to study the conductive properties on single or individual
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