%0 Journal Article
%T Photoconductive Properties of Brush Plated Copper Indium Gallium Selenide Films
%A N. P. Subiramaniyam
%A P. Thirunavukkarasu
%A K. R. Murali
%J Journal of Coatings
%D 2013
%R 10.1155/2013/109176
%X Copper indium gallium selenide (CIGS) films were deposited for the first time by the brush electrodeposition technique. X-ray diffraction studies indicated the formation of single phase chalcopyrite CIGS. Lattice parameters, dislocation density, and strain were calculated. Band gap of the films increased from 1.12£¿eV to 1.63£¿eV as the gallium concentration increased. Room temperature transport parameters of the films, namely, resistivity increased from 0.10£¿ohm£¿cm to 12£¿ohm£¿cm, mobility decreased from 125£¿cm2V£¿1s£¿1 to 20.9£¿cm2V£¿1s£¿1, and carrier concentration decreased from 4.99 ¡Á 1017£¿cm£¿3 to 2.49 ¡Á 1016£¿cm£¿3 as the gallium concentration increased. Photosensitivity of the films increased linearly with intensity of illumination and with increase of applied voltage. 1. Introduction In recent years, quaternary chalcopyrite compound (CIGS) has been one of the most promising absorber materials for high efficiency thin film solar cells [1]. Thin film solar cells based on coevaporated CIGS absorbers ( close to 0.3) have reached up to 20.3% conversion efficiencies at the laboratory scale by using a process requiring high vacuum [2]. From ¡°lab to large-scale production,¡± one of the main challenges is to find an alternative deposition method using nonvacuum equipment that yields economically viable solar cells and is easily scalable. From this point of view, electrochemical deposition is a simple and nonvacuum technique and has a natural advantage of large-area deposition [3]. Therefore, over the last two decades, there has been considerable work done on the growth of CIGS thin films using electrodeposition technique [4¨C6]. So far all electrodeposited (ED) CIGS films need a selenization step under a Se-containing atmosphere to recrystallize the films, as in most cases electrodeposition is employed at low temperature. In the present work we report the properties of CIGS films deposited by the brush plating technique for the first time. 2. Experimental Methods Brush plating was carried out using Selectron Power Pack MODEL 150A-40 V. Layers were brush plated on tin oxide coated conducting substrates of about 50£¿cm2, which is the negative electrode. The stylus, consisting of a carbon rod wrapped in cotton wool, served as the anode. The cotton wool was held in position by a porous sleeve. A sketch of the system is shown in Figure 1. Prior to plating, the stylus was wired to the power supply and the cotton wool was soaked in the electrolyte. The stylus was then brought into contact with the substrate and moved at uniform speed. An electrical current was found passing
%U http://www.hindawi.com/journals/jcoat/2013/109176/