Dielectric functions and critical points of BexZn1−xTe alloys measured by spectroscopic ellipsometry

Abstract

Using a rotating analyzer spectroscopic ellipsometer, we have investigated the complex dielectric function of a series of ternary BexZn1−xTe thin films in the energy range between 0.7 and 6.5 eV for alloy concentrations between x=0.0 and x=0.52. After determining the alloy concentrations using x-ray diffraction and photoluminescence techniques, a standard inversion technique was used to obtain the optical constants from the measured ellipsometric spectra. Analyzing the second derivative of both the real and the imaginary parts of the dielectric constant, we have deduced the critical point parameters corresponding to the electronic transitions in the Brillouin zone. We find that the energy of the critical points with respect to Be concentration does not show any bowing effects unlike many other II–VI semiconductor ternary alloys.

FP‐LAPW investigations of Zn1–xBexS, Zn1–xBexSe and Zn1–xBexTe ternary alloys

“…Hence, the use of Be in ZnX-based ternary alloys (Zn 1-x Be x S, Zn 1-x Be x Se and Zn 1-x Be x Te) should be useful for increasing the hardness of the material and for decreasing degradation rates, which is important for improved device lifetime [7][8][9][10][11]. The other interesting property of beryllium chalcogenides is the possibility of lattice matching to Si substrates in the case of the Zn 1-x Be x Se ternary alloy [12].…”

DFT and X-RAY study of structural, electronic, elastic and optical properties in Be1–XZnXS alloys depending on vegard’s law

“…It is seen that beryllium chalcogens BeX (X = S, Se, Te) that indicate a unique relation between II-VI compounds and large band gaps have recently become focus of interest [5]. Hence, the ternary alloys (Zn 1-x Be x S) that Be composes with ZnX are significant in terms of increasing the hardness of material, decreasing the distortion level and extending the life time of an advanced device [6,7].…”

Determination and modeling of the optical constants of direct band gap Be x Zn 1− x Te grown by molecular beam epitaxy

“…Some authors [1] performed measurements of the ZnTe dielectric function but modeled the optical constants not including continuum exciton contributions, i.e., band-to-band Coulomb enhancement (BBCE) effects at E 0 , E 0 +∆ 0 , E 1 , E 1 +∆ 1 critical points (CPs). References [2] and [3] using Fourier analysis and a second derivative analysis of the dielectric function, respectively, were able to obtain the energies of features related to the CPs. Reference [3], using a second derivative analysis of the dielectric, function provided the only study available of the energies of features related to the CPs of Be x Zn 1-x Te for x > 0.…”

“…References [2] and [3] using Fourier analysis and a second derivative analysis of the dielectric function, respectively, were able to obtain the energies of features related to the CPs. Reference [3], using a second derivative analysis of the dielectric, function provided the only study available of the energies of features related to the CPs of Be x Zn 1-x Te for x > 0. In this work we present a study of the optical constants of direct band gap Be x Zn 1-x Te and their relationship with their band structure.…”

“…The determination of the dielectric function was done by spectroscopic ellipsometry (SE), the details of these measurements as well as the analysis performed are described in Ref. [3]. …”