Electronic and optical properties of HgIn2S4 thiospinels

Abstract

Photoluminescence (PL), transmission (T), reflection (R), wavelength modulated transmission (ΔT/Δλ) and reflection (ΔR/Δλ) spectra of thiospinel HgIn2S4 crystals were investigated in temperature interval form 10 to 300 K. The band gap 1.64 eV (300 K) and 1.666 eV (10 K) are formed by electron transitions from L to Γ points of Brillouin zone. The edge temperature shift coefficient β (ΔEg/ΔT) is equal to 4.3 10–3 eV K−1. The direct energy gap in Γ point (Egdir) corresponds to 1.748 eV. The top valence bands in k = 0 are split by the crystal field on 25 meV. Direct electron transitions a1–a7, observed in energy range 1–6 eV, were interpreted conform the theoretically calculated band structure. The optical functions (n, k, ε1 and ε2) were determined by Kramers-Kronig analysis.