Ellipsometric study of optical properties of GaS x Se 1-x layered mixed crystals

Isik, M.; Gasanly, Nizami

doi:10.1016/j.optmat.2016.02.034

Cited by 8 publications

(1 citation statement)

References 19 publications

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“…However, it is important to note that this measurement did not include the majority of critical point (CP) energies. More recently, Choi et al [29] and Isik et al [36] determined CP energies on the cleavage plane of GaSe over a wider range.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Study of the Temperature Dependence of the Dielectric Function of GaSe Uniaxial Crystals from 27 to 300 K

Le,

Nguyen,

Nguyen

et al. 2024

Nanomaterials

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We report the temperature dependences of the dielectric function ε = ε1 + iε2 and critical point (CP) energies of the uniaxial crystal GaSe in the spectral energy region from 0.74 to 6.42 eV and at temperatures from 27 to 300 K using spectroscopic ellipsometry. The fundamental bandgap and strong exciton effect near 2.1 eV are detected only in the c-direction, which is perpendicular to the cleavage plane of the crystal. The temperature dependences of the CP energies were determined by fitting the data to the phenomenological expression that incorporates the Bose–Einstein statistical factor and the temperature coefficient to describe the electron–phonon interaction. To determine the origin of this anisotropy, we perform first-principles calculations using the mBJ method for bandgap correction. The results clearly demonstrate that the anisotropic dielectric characteristics can be directly attributed to the inherent anisotropy of p orbitals. More specifically, this prominent excitonic feature and fundamental bandgap are derived from the band-to-band transition between s and pz orbitals at the Γ-point.

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Section: Introductionmentioning

confidence: 99%