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)Se 2 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 CuInSe 2 ; secondly, reaction with H 2 Se to form indium selenide; thirdly, the direct reduction of In 3+ to In in the presence of high concentration In 3+ . While the Gallium incorporates through two paths: Ga 3+ reacts with H 2 Se to form gallium selenide; and Ga 2 O 3 forms via Ga 3+ hydrolysis from the increase of local pH.

Effects of sodium sulfamate on electrodeposition of Cu(In,Ga)Se2 thin film

“…The inhibition effect of sodium sulfamate on this reaction in Cu-Se binary system is much weaker than that in Cu unitary system, which might be because sodium sulfamate prefers to work on H 2 SeO 3 . According to the CV analysis in H 2 SeO 3 solution with different concentrations of CuCl 2 [33], the following reduction peak A at about À0.25 V corresponds to the reaction involving Cu + and H 2 SeO 3 preceded by Eq. (6), and the large peak B at about À0.35 V is attributed to formation of CuSe by Eq.…”

Electrochemistry of Gallium

“…They proposed that the insertion of In and Ga into the solid phase might proceed by an underpotential deposition mechanism which involved two different routes: In 3+ and Ga 3+ reduction by a surface-induced effect from Cu 3 Se 2 and/or a reaction with H 2 Se. The same research group also reported 80) the incorporation mechanism of gallium during electrodeposition of Cu(In,Ga)Se 2 thin film from chloride electrolytes using sodium sulfamate as a complexing agent. The insertion of gallium involved two different routes: firstly, Ga 3+ reacted with H 2 Se to form gallium selenide (Ga 2 Se 3 ); secondly Ga 2 O 3 was formed via hydrolysis of Ga 3+ due to the increase of local pH.…”

A short review on the advancements in electroplating of CuInGaSe2 thin films

“…11b) (Fig. 11c) for as-deposited and for annealed CIGSe thin films at 174 and 176 cm −1 , suggesting that the Ga 2 Se 3 phase must be in the dispersed nano-crystalline form which involves in the phase formation only during annealing [109].…”