Fabrication of Copper Indium Diselenide Nanowires
- PDF / 868,773 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 79 Downloads / 222 Views
1031-H13-28
Fabrication of Copper Indium Diselenide Nanowires Sovannary Phok1,2, Suresh Rajaputra1,2, and Vijay Singh1,2 1 Department of Electrical & Computer Engineering, University of Kentuky, 453 Anderson Hall, Lexington, KY, 40506-0046 2 Center for Nanoscale Science & Engineering, University of Kentucky, Lexington, KY, 40506 ABSTRACT We report on the fabrication of copper indium diselinide nanowires (CIS NWs), using a non vacuum and low cost template-assisted technique. Highly ordered nanoporous alumina templates (AAO), a few microns thick were prepared by two-step anodization in either 0.3 M oxalic acid or 3 % sulfuric acid at room temperature. Standardized 2D AAO templates with average length of 2.5 µm and pore size ranging from 8 nm to 40 nm were fabricated. A combination of voltage ramping and pore opening in phosphoric acid was applied to remove the oxide barrier layer at the bottom of the pore in order to expose aluminum, which was used as conducting substrate for electrodeposition. CIS was deposited into the nanoporous AAO by pulse cathodic electodeposition from an aqueous acidic mixture. The electrodeposited nanowires had diameter ranging up to 40 nm depending on the dimension of the template. The nanostructured CIS/AAO were annealed in various atmospheres: (i) in vacuum at 230ºC for several hours and (ii) in flowing argon gas at temperatures ranging from 300ºC to 600ºC for a few minutes. The nanowire composition was analyzed by energy dispersive X-ray (EDX) spectroscopy. High resolution transmission electron microscopy and X-ray diffraction revealed a preferred [112] orientation.
INTRODUCTION Nanostructured materials, including films [1,2] and nanowires (NWs) [3,4] 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 [5] in particular. Among semiconductors of the I-III-VI group, copper indium diselenide (CIS), a ptype semiconductor with direct band gap of about 1 eV has shown promise as an absorber for photovoltaic cells. In particular, polycrystalline gallium doped CIS based solar cells have been reported to exhibit efficiency over 19% [6]. It is generally known that to improve the efficiency of a cell, an absorber layer with an optimal band gap energy tailored to solar spectrum (about 1.45 eV) should be used. One method to tailor the bandgap is by doping the semiconductor. Another method is by size tuning the CIS bandgap, where the small diameter of CIS would lead to quantum confinement. Over the past couple of decades, the fabrication of CIS films by various physical and chemical techniques has been largely explored with various degree of success. On the contrary, the synthesis of nanostructured CIS is still unexplored due to the intrinsic property of CIS to growth into grains larger than 20 nm in size [7]. Yet, nanowires with diameter smaller than 20 n
Data Loading...
