Optical Properties of CuIn1-xGaxSe2 Mixed Crystals

I-III-VI2 compounds are of interest for their use in solar cells and photodiodes. CuIn1-xGaxSe2 is studied for x = 0 - 0.5. Direct linear relationships are established between x and Eg and dEg/dT, and inverse linear with lattice parameters a and c. ( alpha h nu )2 increases mainly linearly with h nu at temp. 296 -22 deg K, and Eg decreases linearly with temp. for 100 - 300 deg K (in both cases the initial parts of the lines are curved), alpha is the absorption coeff. Replacement of Se by S, and energy gap bowing, are also discussed in terms of residual crystal field and disorder, and p - d hybridisation. 12 ref.--R.D.P.