Nanowire Arrays in Multicrystalline Silicon Thin Films on Glass: A Promising Material for Research and Applications in Nanotechnology

Controlled patterning of large grained crystalline silicon (Si) thin films of only ~6µm thickness on glass could be realized using nanosphere lithography (NSL) in combination with reactive ion etching (RIE). Thereby, silicon nanowires (SiNWs) formed with entirely pre-determined geometrical properties such as lengths, diameters and orientation. The SiNWs formed perpendicular to the layer surface, independently of the crystal orientation of the underlying grains. The SiNWs show properties which ideally qualify them for applications in photovoltaics and optoelectronics but they can be interesting for fundamental research in e.g. electronics and nano-mechanics as well. Electron backscatter diffraction (EBSD) studies in a scanning electron microscope (SEM) reveal the structural properties of this novel nano-material. X-ray photoelectron spectro-scopy (XPS) studies showed an excellent surface quality of the SiNWs, with no contamination of reaction gases (fluorine based chemistries). Integrating sphere measurements could prove that patterning of Si thin films with SiNWs permits an enhancement of the spectral absorption of visible light of up to 50% and results in resonant reflection depending on SiNW geometries.