Reflectance difference spectroscopy of GaAs(001) under a [110] uniaxial stress
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We report on reflectance-difference spectra of n-type GaAs(001) under a [110] uniaxial stress. Measurements where carried out in the energy range from 2.5-5.5 eV. This energy range comprises transitions E1, E l Δ1, E′0, E′ 0 Δ′0, E′0 Δ′ 0 Δ0 and E2. RD spectra shows sharp structures around 3.0 eV (E1 and E1 Δ1 transitions). Optical structure is also observed in the energy interval corresponding to the E′0-triplet (4.4 -5.0 eV). Despite the fact that the E2 transition dominates the GaAs reflectance spectrum around 5.0 eV, its contribution to the reflectance-difference (RD) spectra is found to be negligible. This fact was verified by polarized photoreflectance spectra. RD spectra are thus found to comprise only components associated to critical points of A and F symmetries. Furthermore, on the basis of a perturbative approach, we developed a theoretical RD line-shape model that shows an excellent agreement with experimental spectra. Results presented in this paper should probe to be useful in the identification of strain-related features in RD spectra and should contribute to the understanding of the different physical mechanisms leading to reflectance anisotropies.
We report on reflectance-difference spectra of n-type GaAs(001) under a [110] uniaxial stress. Measurements where carried out in the energy range from 2.5-5.5 eV. This energy range comprises transitions E1, E l%2bΔ1, E′0, E′ 0%2bΔ′0, E′0%2bΔ′ 0%2bΔ0 and E2. RD spectra shows sharp structures around 3.0 eV (E1 and E1%2bΔ1 transitions). Optical structure is also observed in the energy interval corresponding to the E′0-triplet (4.4 -5.0 eV). Despite the fact that the E2 transition dominates the GaAs reflectance spectrum around 5.0 eV, its contribution to the reflectance-difference (RD) spectra is found to be negligible. This fact was verified by polarized photoreflectance spectra. RD spectra are thus found to comprise only components associated to critical points of A and F symmetries. Furthermore, on the basis of a perturbative approach, we developed a theoretical RD line-shape model that shows an excellent agreement with experimental spectra. Results presented in this paper should probe to be useful in the identification of strain-related features in RD spectra and should contribute to the understanding of the different physical mechanisms leading to reflectance anisotropies.