+Three-step H2Se/Ar/H2S reaction of metal precursors for large area Cu(In,Ga)(Se,S)2 with uniform Ga distribution

A three-step H2Se/Ar/H2S 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 1^st selenization step gives fine microstructure with Ga accumulation near the Mo back contact, primarily in a Cu9Ga4 phase. Significant grain growth with homogenous through-film Ga distribution is obtained by the 2^nd Ar annealing step. The 3^rd sulfization step completes the reaction process and incorporates S near the Cu(In,Ga)Se2 surface. The resulting films show good adhesion and yielded devices with η = 14.8% and VOC = 612 mV.