Fabrication of Copper Indium Diselenide Nanowires

Abstract

AbstractNanostructured semiconductors have received a great deal of attention due to their unusual physical properties. The possibility of controlling these properties by varying the particle size, shape and surface properties is of great interest for nanoscale device applications in microelectronics, non-linear optics and optoelectronics in particular. Copper Indium diselenide (CIS), a p-type semiconductor with a band gap of about 1.04 eV has shown promise as an absorber for photovoltaic cells. Polycrystalline CIS film has been fabricated by various physical and chemical techniques over the past couple of decades. However, the preparation of nanostructured CIS is still challenging due to the fact that CIS tends to agglomerate resulting in large grains. Furthermore, an annealing step is also required to improve the film properties, which results in increased grain size. Here we report a simple, low cost solution to this problem through electrochemical deposition of CIS into the confined nanopores of an anodic aluminum oxide (AAO) template. The nanoporous aluminum oxide template, a few microns thick was prepared by either a one step or a two anodization in oxalic acidic media. CIS was deposited into the nanoporous AAO template by pulsed cathodic electro-deposition from an aqueous mixture. The electrodeposited nanowires had diameter ranging up to 40 nm and length ranging from 600 nm to 5 μm depending on the length of the template. The hybrid nanostructured CIS/AAO was annealed in vacuum at 230ºC for several hours to achieve stoichiometric CuInSe2 phase. The embedded CIS nanowires were characterized by X-ray diffraction and scanning electron microscopy. The optical bandgap was deduced from UV-Vis absorption spectroscopy measurements.