Incorporation Mechanism of Indium and Gallium during Electrodeposition of Cu(In,Ga)Se2 Thin Film

Abstract

The incorporation mechanism of Indium and Gallium during electrodeposition of Cu(In,Ga)Se2 thin film from chloride electrolytes using sodium sulfamate as a complexing agent has been investigated by means of cyclic voltammetry (CV) coupled with EDS and Raman techniques. Cyclic voltammetry study was performed in unitary Cu, In, Ga and Se systems, binary Cu-Se system, ternary Cu-In-Se and Cu-Ga-Se systems, and quaternary Cu-In-Ga-Se system. EDS and Raman analysis were carried out to determine the evolution of film composition and phases, respectively. The insertion of In involves three different routes: firstly, surface-induced reduction by copper selenides to form CuInSe2; secondly, reaction with H2Se to form indium selenide; thirdly, the direct reduction of In3+ to In in the presence of high concentration In3+. While the Gallium incorporates through two paths: Ga3+ reacts with H2Se to form gallium selenide; and Ga2O3 forms via Ga3+ hydrolysis from the increase of local pH. © 2011 The Electrochemical Society.