Formation of AgGaTe₂ films from (Ag₂Te+Ga₂Te₃)/Ag₂Te or Ga₂Te₃/Ag₂Te bilayer structures

AgGaTe₂ is a novel photovoltaic material, and thin films can be prepared by the close spaced sublimation (CSS) method. AgGaTe₂ films are formed from two types of bilayer structures, namely (Ag₂Te+Ga₂Te₃)/Ag₂Te and Ga₂Te₃/Ag₂Te. The latter structure would exhibit simpler mole ratio controllability for the preparation of the AgGaTe₂ film. The characteristics of AgGaTe₂ layers formed from the Ga₂Te₃/Ag₂Te bilayer structure and the (Ag₂Te+Ga₂Te₃)/Ag₂Te bilayer structure are compared. The formation of AgGaTe₂ is confirmed from both structures, and a remarkable difference in the surface morphologies is observed. Control of the source mole ratio between Ga and Te is also shown to be important for the preparation of Ga₂Te₃ films, because Te vapor leaks from the boat during the sublimation process.