Simplified Model Of Interband Transitions Research Articles

Optical properties of AlxGa1−xN alloy

The optical response of the AlxGa1−xN alloy has been analyzed using a simplified model of interband transitions (E≤10 eV). The present model reveals distinct structures at energies of the E0, E1, F1, and E0′ critical points. The Cauchy−Lorentz expression popularly used for the modeling of the three-dimensional M0 and saddle-point excitonic transitions does not satisfy the Kramers−Krönig requirements but does so if its form is properly modified. As a result, excellent agreement is achieved between the experimental and calculated ε(E) spectra over the entire range of photon energies. Dielectric-related optical constants, such as the complex refractive index, absorption coefficient, and normal-incidence reflectivity, of the AlxGa1−xN alloy are also presented. The high-frequency and static dielectric constants of the AlxGa1−xN alloy are determined to be ε∞(x)=5.27−1.07x and εs(x)=9.28−1.45x, respectively.

Analysis of spectroscopic-ellipsometry and thermoreflectance spectra of Si

Spectroscopic-ellipsometry (SE) and thermoreflectance (TR) spectra of bulk single-crystalline Si are measured. Measurements are made on the same sample in the 2.5–6.0 eV range at room temperature. These data are analyzed on the basis of a simplified model of interband transitions, named the model dielectric function. Results are in satisfactory agreement with the experimental data over the entire range of photon energies. The finding definitely links the temperature-induced change in the dielectric function (TR) to the first derivative of the dielectric function (SE).

Optical Properties of (AlxGa1-x)0.5In0.5P Quaternary Alloys

The dielectric function spectra ε(E) of (Alx Ga1-x )0.5In0.5P quaternary alloys lattice-matched to GaAs have been measured at room temperature in the 1.2–5.5-eV photon-energy range using spectroscopic ellipsometry (SE). The measured SE spectra show distinct structures at energies of the E0, E1 and E2 critical points. These spectra are analyzed on the basis of a simplified model of interband transitions. This model enables us to obtain the, optical response in (Alx Ga1-x )0.5In0.5P alloys of arbitrary composition x and photon energy E=\\hbarω. Results are presented for the complex refractive index (n*=n+ ik), absorption coefficient (α) and normal-incidence reflectivity (R) of these alloys.

Optical Constants of Cubic ZnS

The real (?1) and imaginary (?2) parts of the dielectric function of cubic ZnS have been measured by spectroscopic ellipsometry in the 1.2-5.6 eV photon-energy range at room temperature. The measured dielectric-function spectra reveal distinct structures at energies of E0/(E0+?0) critical points. These data are analyzed on the basis of a simplified model of interband transitions. Results are in satisfactory agreement with the experimental data over the entire range of photon energies. Dielectric-related optical constants of cubic ZnS, such as the complex refractive index (n*=n+ik), the absorption coefficient (?) and the normal-incidence reflectivity (R), are presented and analyzed.

Optical Constants of In1-xGaxSb Ternary Alloys: Experiment and Modeling

The optical response of In1-xGaxSb ternary alloys in the 1.5-5.4-eV photon-energy range at room temperature is measured by spectroscopic ellipsometry (SE). The measured SE data show distinct structures at energies of the E1, E1+Δ1, E0′, E0′+Δ0′, E2 and E1′ critical points. These spectra are analyzed on the basis of a simplified model of interband transitions. The model proposed here enables us to obtain the optical response in In1-xGaxSb alloys of arbitrary composition (x) and photon energy (E=\\hbarω). Results of the surface-treatment effect on the pseudodielectric functions are also presented.