TY - JOUR
T1 - Interband transitions and phonon modes in BxGa1−xAs (0 < x < 0.03) and GaNyAs1−y (0 < y < 0.037)
T2 - A comparison
AU - Leibiger, Gunnar
AU - Gottschalch, Volker
AU - Riede, Volker
AU - Schubert, Mathias
AU - Hilfiker, James N.
AU - Tiwald, Thomas E.
PY - 2003/5/22
Y1 - 2003/5/22
N2 - We report on the experimental observation of direct interband-critical-point transitions and phonon modes in BxGa1−xAs alloys (0 < x < 0.03) and their evolution with increasing boron concentration using spectroscopic ellipsometry and Raman scattering. Our results are compared to the corresponding values in the GaNyAs1−y (0 < y < 0.037) material system. For BxGa1−xAs, we obtain only a small bowing coefficient of the Eg(x) dependence in contrast to the giant redshift of the GaNyAs1−y band-gap energy with y. The higher lying interband-transition energies of BxGa1−xAs (E1, E1 + Δ1, E0′, E2, and E1′) are slightly redshifted with increasing boron concentration. A similar behavior is found for the critical points E0′, E2, and E1′ in GaNyAs1−y. In BxGa1−xAs, we observe, as in GaNyAs1−y, a two-mode phonon behavior using Raman scattering. However, from infrared-ellipsometry or -transmission experiments, we can estimate that the oscillator strength or polarity of the BAs-like phonon is at least one order of magnitude smaller than the oscillator strength of the GaN-like phonon measured at a GaNyAs1−y layer with comparable thickness and composition. All results will be explained using a simple model that takes into account the different nature of the chemical bonds in both alloy types.
AB - We report on the experimental observation of direct interband-critical-point transitions and phonon modes in BxGa1−xAs alloys (0 < x < 0.03) and their evolution with increasing boron concentration using spectroscopic ellipsometry and Raman scattering. Our results are compared to the corresponding values in the GaNyAs1−y (0 < y < 0.037) material system. For BxGa1−xAs, we obtain only a small bowing coefficient of the Eg(x) dependence in contrast to the giant redshift of the GaNyAs1−y band-gap energy with y. The higher lying interband-transition energies of BxGa1−xAs (E1, E1 + Δ1, E0′, E2, and E1′) are slightly redshifted with increasing boron concentration. A similar behavior is found for the critical points E0′, E2, and E1′ in GaNyAs1−y. In BxGa1−xAs, we observe, as in GaNyAs1−y, a two-mode phonon behavior using Raman scattering. However, from infrared-ellipsometry or -transmission experiments, we can estimate that the oscillator strength or polarity of the BAs-like phonon is at least one order of magnitude smaller than the oscillator strength of the GaN-like phonon measured at a GaNyAs1−y layer with comparable thickness and composition. All results will be explained using a simple model that takes into account the different nature of the chemical bonds in both alloy types.
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U2 - 10.1103/PhysRevB.67.195205
DO - 10.1103/PhysRevB.67.195205
M3 - Article
AN - SCOPUS:0038164871
VL - 67
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 19
ER -