SEMICONDUCTOR SCIENCE AND TECHNOLOGY, cilt.40, sa.12, 2025 (SCI-Expanded, Scopus)
TlInS2 exhibits remarkable optical properties, making the compound strong candidate for next-generation optoelectronic and nonlinear optical (NLO) applications. In this study, linear and NLO characteristics of TlInS2 crystal were systematically investigated using spectroscopic ellipsometry. The optical band gap was determined to be 2.41 eV, confirming its indirect nature, which plays a crucial role in tailoring its optoelectronic behavior. The dispersion energy and single effective oscillator energy were found to be 23.2 and 4.69 eV, respectively, based on the Wemple-DiDomenico model. The zero-frequency refractive index was calculated as 2.44, corresponding to a dielectric constant of 5.94. Using the linear refractive index, the nonlinear refractive index and first- and third-order susceptibilities were calculated, indicating a potentially strong NLO response. Additionally, the high oscillator strength and optical moments suggest its potential for efficient light-matter interactions. These results indicate that TlInS2 is a promising material for optical modulators and nonlinear frequency conversion.