Nitrogen dependence of the GaAsN interband critical points E1 and E1+Δ1 determined by spectroscopic ellipsometry

Leibiger, G.; Gottschalch, V.; Rheinländer, B.; Šik, J.; Schubert, M.

doi:10.1063/1.1309021

Cited by 43 publications

(22 citation statements)

References 18 publications

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“…5,6 SE could be particularly valuable for retrieving information on the CPs in dilute nitrides where the oscillator strengths of the N-induced transitions are relatively small ͑especially for low-N content samples as in our case͒ and there is N-induced broadening. [7][8][9] Figure 1 shows experimental ͑scatters͒ and best-fit calculated ͑solid lines͒ data in the GaAs 0.9−x N x Sb 0.1 pseudodielectric function representation for the different nitrogen compositions. We determine the dielectric function of GaAs 0.9−x N x Sb 0.1 from the experimental ellipsometric data analysis using a five-layer model: GaAs substrate/ GaAs 0.9−x N x Sb 0.1 layer/GaAs caplayer/GaAs native oxide/ ambient.…”

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Effect of nitrogen on the GaAs0.9−xNxSb0.1 dielectric function from the near-infrared to the ultraviolet

Sédrine

Bouhafs

Harmand

et al. 2010

Applied Physics Letters

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We study the effect of nitrogen on the GaAs0.9−xNxSb0.1 (x=0.00, 0.65%, 1.06%, 1.45%, and 1.90%) alloy dielectric function by spectroscopic ellipsometry in the energy range from 0.73 to 4.75 eV. The compositional dependences of the critical points energies for the GaAs0.9−xNxSb0.1 are obtained. In addition to the GaAs intrinsic transitions E1, E1+Δ1, and E0′, the nitrogen-induced Γ-point optical transitions E0 and E+, together with a third transition E#, are identified. We find that with increasing the N content, the E0 transition shifts to lower energies while the E+ and E# transitions shift to higher energies. We suggest that the origin of the E0, E+, and E# transitions may be explained by the double band anticrossing (BAC) model, consisting of a conduction BAC model and a valence BAC model.

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Effect of nitrogen on the GaAs0.9−xNxSb0.1 dielectric function from the near-infrared to the ultraviolet

Sédrine

Bouhafs

Harmand

et al. 2010

Applied Physics Letters

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“…We also observe a blueshift of the E 1 transition from about (3.675 AE 0.002) eV to (3.709 AE 0.006) eV for GaP 0.977 N 0.023 . This blueshift, which is due to the dominating influence of alloying (E 1 b-GaN % 7 eV), was also observed for GaAsN alloys using SE [9]. The CP's E 1 , E 0 1 , and E 0 0 , are due to transitions along the D direction and at the G-point of the first Brillouin zone (BZ), respectively [11,12].…”

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“…They observed a two-mode phonon behaviour, i.e., the GaP-like (w LO1 % 401-399 cm --1 ) and the GaN-like (w LO2 % 495-503 cm --1 ) longitudinal optical phonons. Recently, spectroscopic ellipsometry (SE) was used as novel technique for precise determination of phonon modes and critical points in GaN y As 1--y [8,9]. SE for mid-infrared (mir) and near-infrared (nir) to vacuum-ultraviolet (vuv) wavelengths are used in this study to investigate phonon modes and critical points of GaP 0.977 N 0.023 , respectively.…”

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Phonon Modes and Critical Points of GaPN

Leibiger

Gottschalch

Schwabe

et al. 2001

phys. stat. sol. (b)

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Spectroscopic ellipsometry in the mid-infrared and near-infrared to vacuum-ultra violet spectral range is employed to study the phonon properties and critical points of a GaP 0.977 N 0.023 layer grown on GaP. We observe a two-mode phonon behaviour, i.e., a GaN-like and a GaP-like phonon. We detect six critical-point structures, which we assign as E dir 0 , E 0 0 , E 1 , E 0 1 , E 1 2 and E 2 2 transitions. We observe a blueshift of the direct band gap E 0 dir and of the E 1 transition in contrast to the redshift of the photoluminescence peak and the absorption tail, which we observed on the same sample. The critical-point energies E 0 0 , E 0 1 , and E 2 do not show any significant composition dependence.Introduction Nitrogen-doped GaP has been used for decades as active material in green light emitting diodes. With the availability of modern non-equilibrium growth techniques, metastable GaNP alloys, with nitrogen concentrations above the impurity limit can be grown successfully [1]. Similar to GaN y As 1--y , incorporation of only a few percent of nitrogen in GaN y P 1--y leads to a strong redshift of the fundamental band-gap energy [2]. The underlying microscopic picture of this effect is still in discussion [3-6]. However, up to now no report on the observation of critical-point transitions, with energies larger than that of the photoluminescence-emission energy has been published. Likewise, only little is known about the phonon properties of GaNP. Kent et al. [6] performed large-supercell pseudopotential calculations and predicted a negligible y dependence of the E 1 transition. Buyanova et al. [7] reported on Raman measurements of GaP 1--y N y (y 0.03) layers. They observed a two-mode phonon behaviour, i.e., the GaP-like (w LO1 % 401-399 cm --1 ) and the GaN-like (w LO2 % 495-503 cm --1 ) longitudinal optical phonons. Recently, spectroscopic ellipsometry (SE) was used as novel technique for precise determination of phonon modes and critical points in GaN y As 1--y [8,9]. SE for mid-infrared (mir) and near-infrared (nir) to vacuum-ultraviolet (vuv) wavelengths are used in this study to investigate phonon modes and critical points of GaP 0.977 N 0.023 , respectively.

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“…In this figure, we observed that the E 1 and E 1 +D 1 transitions in the GaAsN alloys shift to high energies with increasing nitrogen content in the samples. This shift is originated by the combined effects of strain and alloying in the films [10]. The strain produces a red shift that can be estimated for E 1 by…”

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confidence: 99%