CRYSTAL-GROWTH AND OPTICAL-PROPERTIES OF CUAL(SXSE1-X)(2) ALLOYS

Single crystals of CuA1(SxSe1-x)(2) alloys have been successfully grow n by the chemical vapor transport method. Photoreflectance (PR) and ph otoluminescence (PL) measurements have been carried out at 77K. From P R measurements, exciton energies (in eV) at 77K have been obtained as a function of alloy composition a: EA 3.546x + 2.736(1 - x) - 0.35x(1 - x), E-B = 3.709x + 2.849(1 - x) - 0.39x(1 - x); Ec = 3.692x + 3.012( 1 - x) - 0.33(1 - x). PL spectra are dominated by a broad emission ban d centered at 2.0 eV, although weak exciton and edge emission (2.9 eV) peaks have been observed for 0.84 less than or equal to x less than o r equal to 0.96 and 0.68 less than or equal to x less than or equal to 0.96, respectively.