MICRO-RAMAN SPECTROSCOPY ON POLYCRYSTALLINE CUINSE(2) FORMATION

The crystalline formation of CuInSe2 thin films has been investigated using micro-Raman spectroscopy and AES composition analysis. It is con firmed that the Raman peaks are stongly dependent on the surface morph ology and the Cu:In:Se ratio. In the films annealed at 315 degrees C, crystalline grains larger than 2 mu m show Raman peaks at 174 cm(-1) a nd 258 cm(-1). The In content is very low and the Cu:Se ratio is about 1:1 in these grains. The low In concentration is thought to be due to the formation of In2O3 on the surface. On the other hand, random stru ctures of 1-2 mu m grains found in films annealed at temperatures belo w 305 degrees C show peaks at 174 cm(-1) and 186 cm(-1) instead of 258 cm(-1) and have a Cu: In: Se ratio of 1 : 1 : 3-4. Thus the 186 cm(-1 ) peak is thought to be related to a Cu, In-deficient phase when compa red to stoichiometric CuInSe,. The optimum annealing condition was fou nd by analyzing the Raman spectra and composition of different crystal line CuInSe, grains. Films annealed under this condition exhibited a c lear Raman peak at 174 cm(-1) and consisted of clusters of crystals le ss than 1 mu m in size.