Optics and Spectroscopy, 2025 Volume 133, Issue 3,Pages 274–280(Mi os1610)
Proceedings of The XXVIII Annual International Conference "Saratov Fall Meeting 2024", September 23-27, 2024, Saratov, Russia. Advanced materials in optoelectronics, laser physics, and photonics Optical materials
Influence of tellurium and zinc stoichiometry on the ellipsometric spectra of ZnTe/GaAs (100)
Abstract:
The effect of Zn:Te molecular flux stoichiometry on the optical properties of zinc telluride was studied. The considered ZnTe structures were obtained on GaAs (100) substrates using molecular beam epitaxy. The ellipsometric spectra of the $\psi$ parameter were determined using optical ellipsometry. The study showed that the Van Hove singularities $E_1$ and $E_1+\Delta_1$, corresponding to 3.65 eV and 4.27 eV, are characteristic of the ZnTe compound. Excess tellurium in the incident substance flux leads to a simultaneous decrease in the amplitude and broadening of the extrema in the $\psi(\lambda)$ spectrum due to the formation of defects that absorb visible radiation. The spectra of the psi parameter and the imaginary component of the permittivity in the $E>E_g$ region have extrema that are similar in energy position. When one of the components predominates in the Zn:Te ratio, the energy positions of the critical points remain constant at different sample thicknesses. However, excess Zn in the Zn:Te ratio leads to uncertainty in the energy position of the absorption edge. The results of the study will be useful for ellipsometric express control of stoichiometry and assessment of the crystalline quality of binary solid solutions of the À$_2$Â$_6$ group in the composition of epitaxial layers.
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