Spectroscopic properties of nonlinear optical LiGaTe2 crystal

Abstract The nonlinear crystal LiGaTe 2 (LGT) with chalcopyrite structure was grown by the Bridgman–Stockbarger technique. LGT is transparent in the 0.52–16 μm range. Fundamental absorption edge is due to direct allowed transitions; Band gap values are 2.65 and 2.41 eV at 80 and 300 K, respectively. Vibrational, Raman and IR absorption spectra demonstrate four groups of lines in the 50–350 cm −1 . Intense orange photoluminescence (PL) in a broad 605 nm band, excited at band-to-band transitions and quenched in the 180–250 K range is related to self-trapped excitons. Weaker PL components at 510, 729 and 898 nm are associated supposedly with F-centers and their complexes. According to PL excitation spectra valence band is split into three components: Γ 7 (A), Γ 6 (B) and Γ 7 (C), from which electrons are excited to the bottom of the conduction band Γ 6 . The crystal field splitting ( Δ CF ) and the spin–orbit splitting ( Δ SO ) were determined to be −0.75, and 0.62 respectively, at liquid nitrogen temperature.