Interband transitions and phonon modes inBxGa1−xAs(0<~x<~0.03)andGaNyAs1−y(0<~y<~0.037): A comparison

摘要: We report on the experimental observation of direct interband-critical-point transitions and phonon modes in ${\mathrm{B}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ alloys $(0l~xl~0.03)$ their evolution with increasing boron concentration using spectroscopic ellipsometry Raman scattering. Our results are compared to corresponding values ${\mathrm{GaN}}_{y}{\mathrm{As}}_{1\ensuremath{-}y}$ $(0l~yl~0.037)$ material system. For ${\mathrm{B}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As},$ we obtain only a small bowing coefficient ${E}_{g}(x)$ dependence contrast giant redshift band-gap energy y. The higher lying interband-transition energies ${(E}_{1}{,E}_{1}+{\ensuremath{\Delta}}_{1},$ ${E}_{0}^{\ensuremath{'}},$ ${E}_{2},$ ${E}_{1}^{\ensuremath{'}})$ slightly redshifted concentration. A similar behavior is found for critical points ${E}_{1}^{\ensuremath{'}}$ ${\mathrm{GaN}}_{y}{\mathrm{As}}_{1\ensuremath{-}y}.$ In observe, as ${\mathrm{GaN}}_{y}{\mathrm{As}}_{1\ensuremath{-}y},$ two-mode However, from infrared-ellipsometry or -transmission experiments, can estimate that oscillator strength polarity BAs-like at least one order magnitude smaller than GaN-like measured layer comparable thickness composition. All will be explained simple model takes into account different nature chemical bonds both alloy types.