Structural study of flash evaporated CuInSe2 thin films

The flash evaporation technique was used to deposit thin films of the terna ry semiconductor CuInSe2. The influence of different preparation parameters , namely the substrate temperature (from room temperature (RT) to 350 degre esC) and the post-annealing period (1, 2 and 5 h) was studied. X-ray diffra ction was used to investigate the nature of the prepared films and to ident ify the formed phases. Rietveld whole-pattern fitting showed the presence o f mainly CIS phase with lattice parameter, a = 0.5782 nm and c = 0.1162 nm. An amorphous nature was shown for films prepared at RT which were not subj ected to post-annealing. Higher substrate temperatures( greater than or equ al to 200 degreesC) and post-annealing result in a crystalline nature. In a ddition to the ternary CuInSe2 as the predominant phase, other minor binary phases, mainly Cu7In4, are present. The preparation conditions greatly aff ect both the crystallinity of the films and the ratio between the ternary C IS and Cu7In4 phase. For the best crystallinity and the highest ratio of CI S, a substrate temperature of 250 degreesC and postannealing at 350 degrees C for 3-4h are recommended. (C) 2001 Elsevier Science Ltd. All rights reser ved.