+Three-step H 2 Se/Ar/H 2 S reaction of metal precursors for large area Cu(In,Ga)(Se,S) 2 with uniform Ga distribution

A three-step H 2 Se/Ar/H 2 S reaction is used to process Cu-In-Ga metal precursors to form Cu(In,Ga)(Se,S) 2 films over 10 × 10 cm2 substrates. The 1st selenization step gives fine microstructure with Ga accumulation near the Mo back contact, primarily in a Cu 9 Ga 4 phase. Significant grain growth with homogenous through-film Ga distribution is obtained by the 2nd Ar annealing step. The 3rd sulfization step completes the reaction process and incorporates S near the Cu(In,Ga)Se 2 surface. The resulting films show good adhesion and yielded devices with η = 14.8% and V OC = 612 mV.