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.