STRUCTURE AND PHYSICOCHEMICAL PROPERTIES OF CUIN5S8

CuIn5S8 single crystals 14 mm in diameter and 50 mm in length were gro wn by the Bridgman-Stock-barger technique. The compound crystallizes i n the spinel structure with a = 1.0769 nm. The crystals show n-type co nductivity with a resistivity of 10(-2) to 5 x 10(-3) Omega cm and ele ctron concentration of similar to(2-3) x 10(18) cm(-3). As determined from the transmittance near the the fundamental absorption edge, the d irect and indirect band gaps are, respectively, 1.51 and 1.29 eV at 29 5 K and 1.57 and 1.40 eV at 77 K. The linear thermal expansion coeffic ient determined from the temperature dependence of the lattice constan t is 11.1 x 10(-6), 8.0 x 10(-6), and 16.8 x 10(-6) K-1 at room temper ature, 80 K, and 650 K, respectively.