Optical properties of the quaternary alloy system Culn(SxSe1-x)(2) investigated by spectroscopic ellipsometry

Experimental results for the pseudodielectric function <epsilon > of CuIn(S xSe1-x)(2) alloy system are reported. The investigation has been performed on the full composition range using crystals cut from ingots of 10 mm diame ter and 40 mm length. The ingots were grown using the classical Bridgman me thod. Ellipsometric measurements were performed at room temperature in the range 1.5-5.5 eV. The energies of critical points have been determined from the imaginary part of the dielectric function. The transition energies (E- 1, E-2, E-3, and E-4) are found to shift linearly to higher energies as the sulfur content increases. The copper d level is found to be dominant in th e ranges 2.5-3.5 eV for CuInSe2 and 2.8-4 eV for CuInS2. (C) 1999 American Institute of Physics. [S0021-8979(99)06524-X].