Above-bandgap ordinary optical properties of GaSe single crystal

Abstract

We report above-bandgap ordinary optical properties of -phase GaSe single crystal. Reference-quality pseudodielectric function ͗͑E͒͘ = ͗ 1 ͑E͒͘ + i͗ 2 ͑E͒͘ and pseudorefractive index ͗N͑E͒͘ = ͗n͑E͒͘ + i͗k͑E͒͘ spectra were measured by spectroscopic ellipsometry from 0.73 to 6.45 eV at room temperature for the light polarization perpendicular to the optic axis ͑E ៝ Ќ ĉ͒. The ͗͘ spectrum exhibited several interband-transition critical-point structures. Analysis of second-energy derivatives calculated numerically from the measured data yielded the critical-point energy values.

Optical characterization of Ga2SeS layered crystals by transmission, reflection and ellipsometry

“…This value is much smaller than the sample thickness of 320 μm. Similar oscillations were also observed in the ellipsometry analysis of GaSe layered crystal reported by Choi et al 26 According to researchers, a group of layers partially lose its binding to the remaining bulk due to its weak interlayer binding energy when the top few layers are cleaved. 1.8 μm corresponds to the total thickness of group of layers mentioned in the explanation.…”

“…This is also verified from the CP analysis. The obtained spectra of Ga 2 SeS seem similar to those of GaS 25 and GaSe 26 as a shape and number of peaks but gets a position between these spectra in terms of energy. This is an expected result since the band gap energy value of Ga 2 SeS is between those of GaSe and GaS.…”

Growth and optical parameters of GaSe:Te crystals

“…The general view of the dependences n(λ) and k(λ) is similar to the dependences determined by spectral ellipsometry for pure GaSe crystals [15]. However, a number of differences in the curve parameters are observed.…”

“…At the same time, the energy position 3.79 eV (327 nm) is the same as in pure GaSe. The intrinsic absorption edge of the GaSe:Te crystals lies in the region of shorter wavelengths as compared to the known data, which is related to special features of the measurement technique and rules of selection for polarized radiation [15].…”

Structural and thermal investigations of an amorphous GaSe9 alloy using EXAFS, cumulant expansion, and reverse Monte Carlo simulations

“…There is strong covalent bonding within the layers, but between them the interaction is weak, caused by van der Waals forces, 16 and this fact introduces a high anisotropy in the optical and electrical properties of GaSe. Different methods can be used to produce Ga-Se alloys in bulk, powder or thin films forms, such as chemical vapour deposition, 6 molecular beam epitaxy, 17 melt-quenching (MQ), 13,14,[18][19][20][21] Bridgman method, [22][23][24][25] vacuum evaporation, 13,14,26 and mechanical alloying (MA). 15,27,28 Many experimental techniques were used to investigate optical (transmittance, reflectance and absorption spectroscopies, [13][14][15]23,26 ellipsometry 25 ), vibrational (Raman spectroscopy 15,27,29 ), electrical (conductivity 26 ), thermal, 15,[18][19][20][21]27,28 and photothermal 28 properties of Ga-Se alloys.…”