Effect of reaction temperature on Cu(InGa)(SeS)2 formation by a sequential H2Se/H2S precursor reaction process

The effect of sulfization temperature on Ga through-film uniformity in a 2-reaction H2Se/H2S precursor process for Cu(InGa)(SeS)2 was studied. Cu0.8Ga0.2/In bi-layer precursors were prepared by sputter deposition. The precursors were then partially selenized at 450 °C, followed by sulfization at temperatures ranging from 450 to 550 °C. The observed threshold temperature for Ga homogenization during sulfization was ∼500 °C. It is speculated that this threshold temperature possibly derives from a solid→liquid phase transition at 485 °C on the Ga-rich edge of the γ1-Cu9Ga4 phase region.