Isotropic dielectric functions of highly disordered AlxGa1−xInP (0⩽x⩽1) lattice matched to GaAs

Abstract

Determination of the complex dielectric function and the critical-point energies of (Al x Ga 1Ϫx) 0.51 In 0.49 P, over the full range of composition x and for photon energies E from 0.75 to 5 eV is reported from variable angle of incidence spectroscopic ellipsometry. Native-oxide effects on the (Al x Ga 1Ϫx) 0.51 In 0.49 P optical functions are removed numerically. The highly disordered state of the metalorganic vapor-phase epitaxy grown samples is analyzed by transmission electron microscopy. Optical anisotropy investigations revealed that the order-induced optical birefringence is negligible throughout. The augmentation of A. D. Rakić and M. L. Majewski ͓J. Appl. Phys. 80, 5909 ͑1996͔͒ to Adachi's critical-point model, i.e., consideration of Gaussian-like broadening function instead of Lorentzian broadening, is used for calculation of the isotropic (Al x Ga 1Ϫx) 0.51 In 0.49 P dielectric function. The optical functions spectra consistently match the experimental data, whereas previously reported model dielectric functions fail to reproduce the correct absorption behavior of the quaternary, especially near the fundamental band-to-band transition. The results are compared to those presented previously, and influence of spontaneous chemical ordering is discussed.

AlGaInP growth parameter optimisation during MOVPE for opto-electronic devices

“…Using the recently published room temperature data from Ref. [10] as a starting point, we analysed quantitatively the reflectance transients taken during growth of different RT-lattice matched AlGaInP layers for establishing a high temperature database of the optical constants n and k. The dependence of these constants on the aluminium content is shown in Fig. 4a and b for a growth temperature of 700 1C at two wavelengths (l ¼ 563 nm (2.2 eV) and 950 nm (1.30 eV)).…”

“…These are of importance both for quantitative analysis of curvature measurements and for an in situ determination of the aluminium content x of the lattice matched AlGaInP layers. For this purpose we established a high-temperature database for the AlGaInP optical constants derived from recently published room temperature (RT) data [10] and in situ measured transients in the UV-vis range. This database is applied for an in-situ determination of the growth rate and the aluminium composition.…”

Dielectric function of amorphous tantalum oxide from the far infrared to the deep ultraviolet spectral region measured by spectroscopic ellipsometry

“…45 are often utilized. 43,46 Separate MDFs are employed in this work for the tantalum oxide IR and NIR-VUV dielectric function spectra, respectively. For the NIR-VUV data a general parametric functional model based on the Kim and Garland approach [47][48][49] is used to describe and fit ⑀ Ta for amorphous tantalum oxide.…”

Optical properties of undoped AlN/GaN superlattices grown by metalorganic vapor phase epitaxy

“…3 Results and discussion Figure 1 shows experimental and best-fit calculated data in the pseudodielectric function hei representation, [6] where only the real part he 1 i is included for brevity. An isotropic five-phase model (substrate/AlN buffer/GaN buffer/SL/ambient) was used, where the SL was treated as homogeneous layer with thickness according to growth parameters, and all other thickness values were allowed to vary during the best-fit calculation.…”

“…1 as well. The same MDF approach, as described in [6], was then used to obtain e for the SL layer. The MDF comprised contributions from two M 0 -type band-to-band transitions, static dielectric polarizability, and an undamped harmonic oscillator (pole) to account for higher energy transitions outside the studied spectral range.…”