A study was made of Cu, In and Ga interdiffusion in In2Se3/CuGaSe2/SnO2/glass thin-film heterostructures annealed at various temperatures (table 18). The use of CuGaSe2 in place of Cu(In,Ga)Se2 was required for In diffusion studies. The CuGaSe2 layers were grown by close-spaced vapor transport for 2 types of source having different grain sizes. The In2Se3 films were deposited by thermal evaporation, and the heterostructures were annealed in vacuum at various temperatures and analyzed by secondary ion mass spectroscopy. The Cu, In and Ga secondary ion mass spectrometry concentration profiles showed that the Cu diffused up to the In2Se3 film surface and that the In could diffuse far away from the In2Se3/CuGaSe2 interface towards the SnO2. The Cu, In and Ga diffusion were studied, and the interdiffusion parameters were calculated. The simultaneous interdiffusion of Cu and In led to the formation of a p–n junction.

Diffusion of Cu, In and Ga in In2Se3/CuGaSe2/SnO2 Thin Film Photovoltaic Structures. K.Djessas, S.Yapi, G.Massé, M.Ibannain, J.L.Gauffier: Journal of Applied Physics, 2004, 95[8], 4111-6