Growth and characterization of single crystals of ternary chalcogenides for laser applications

Abstract

Bulk single crystals up to 20 mm in diameter and 40 mm long for LiInS2 and up to 10 mm, 20mm, respectively, for LiInSe2 have been grown. Their color changed from colorless to rose for the first one and from yellow to dark red for the other. All crystals have wurtzite-type lattice, lattice parameters were determined. A band gap was found to be 3.72 and 3.57 eV for LiInS2 and 3.02, 2.86 eV for LiInSe2 at 80 and 300K respectively. Color variations are due to point defects, first of all to interstitial sulfur, resulting in additional wide absorption bands in the shortwave part of transparency range. For LiInS2 the SHG phase matching conditions were found to be similar for samples of different color and some difference from Boyd's predictions of 1973 was shown.