Typical ω-2θ scan of the (Al x Ga1− x )0.52In0.48P layers grown on GaAs(001) illustrated using the sample with x = 0.627.
Best matched curves (continuous lines) and experimental (dotted lines) data for the Ψ and Δ spectra of (Al x Ga1− x )0.52In0.48P layers grown on GaAs(001), illustrated using the sample with x = 0.627. The arrows are provided as guides to indicate the direct transitions related to the Γ, L, and X points of symmetry. The ellipses with arrows identify the set of curves associated with the Ψ or Δ spectra.
(a) Real (ε1) and (b) imaginary (ε2) parts of the dielectric function of (Al x Ga1− x )0.52In0.48P for x = 0.052, 0.331, 0.427, 0.627, and 1. The transitions related to the Γ, L, and X points of symmetry are highlighted.
(a) Dispersion curve of the index of refraction and (b) absorption coefficient spectra for the (Al x Ga1− x )0.52In0.48P films. The values indicate the Al compositions x of the different curves indicated by the arrows.
Illustration of the difference in transition probability near the fundamental band edge between an indirect transition and a direct transition, using the joint density of states (JDOS) as a function of the energy near the fundamental band edge.
Best matched parameter values (symbols) for the dielectric function of the (Al x Ga1− x )0.52In0.48P films expressed as a function of the Al composition x. The energy values are represented in (a), the amplitude values A 0 and A 1 in (b), and the broadening B 0 and B 1 values in (c). The indices 0 and 1 refer to the E 0 and E 1 transitions, respectively. The continuous line describing E 0(x) is taken from Ref. 23 , whereas the continuous line describing E 1(x) is a linear regression of the energies obtained from the VASE analysis. The continuous curves describing the composition dependency of the amplitude and broadening values are the results of quadratic regressions of the parametric values obtained from the VASE analysis. The symbols for which no error bar is apparent have uncertainties within the dimension of the symbol.
Comparison between the change in amplitude A1 as a function of the Al composition x in (Al x Ga1− x )0.52In0.48P. The symbols represent the values reported in this work and the continuous line the quadratic regression obtained with these values. The dashed curve is the empirical behavior reported in Ref. 8 and normalized to our data at x = 0 for comparison.
(Al x Ga1− x )0.52In0.48P VASE magnitude parameters. The values of the energy E, the broadening B, and the amplitude A are given for the different CPs and the pole. The estimated uncertainties on the Al, In, and Ga compositions are at most ±0.003, ±0.001, and ±0.003, respectively. For the sample Al0.326In0.484Ga0.190P, the uncertainty on the Al, In, and Ga compositions is estimated to be ±0.010. For the ternary film, the uncertainty on the Al composition is ±0.001. The estimated uncertainties for the thicknesses are well within ±1 nm. The estimated uncertainties for the amplitude and broadening parameters are ±0.004 for A 0, ±0.08 for A 1, ±0.06 for A 2, ±0.7 meV for B 0, ± 2 meV for B 1, and ±3 meV for B 2, while they are within ±2 meV for the energies. Finally, the estimated uncertainties for the amplitude and energy parameters of the pole for all compositions are within ±0.39 and ±10 meV, respectively.
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