Anisotropic absorption and emission of bulk<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:mn>1</mml:mn><mml:mover accent="true"><mml:mn>1</mml:mn><mml:mo>¯</mml:mo></mml:mover><mml:mn>00</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math>AlN

Feneberg, Martin; Romero, M. F.; Röppischer, Marcus; Cobet, Christoph; Esser, N.; Neuschl, Benjamin; Thonke, Klaus; Bickermann, Matthias; Goldhahn, R.

doi:10.1103/physrevb.87.235209

Cited by 68 publications

(49 citation statements)

References 61 publications

(52 reference statements)

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“…Substitution of Ga for Al in the corundum sesquioxide is expected to decrease transition energies. Similar behavior is reported for β sesquioxides [20] or when comparing AlN and GaN, both in the zinc-blende [65] and in the wurtzite polytype [66]. Also the classical III-V zinc-blende semiconductors AlAs and GaAs show a similar behavior [67].…”

Section: B Optical Properties In the Visible-to-ultraviolet Spectralsupporting

confidence: 63%

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Feneberg

Nixdorf

Neumann

et al. 2018

Phys. Rev. Materials

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The linear optical response of metastable α-Ga 2 O 3 is investigated by spectroscopic ellipsometry. We determine the ordinary dielectric function from lattice vibrations up to the vacuum ultraviolet spectral range at room temperature for a sample with a (0001) surface. Three out of four E u infrared-active phonon modes are unambiguously determined, and their frequencies are in good agreement with density functional theory calculations. The dispersion of the refractive index in the visible and ultraviolet part of the spectrum is determined. High-energy interband transitions are characterized up to 20 eV. By comparison with the optical response of α-Al 2 O 3 and with theoretical results, a tentative assignment of interband transitions is proposed.

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Section: B Optical Properties In the Visible-to-ultraviolet Spectralsupporting

confidence: 63%

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Feneberg

Nixdorf

Neumann

et al. 2018

Phys. Rev. Materials

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“…This yields E d ¼ ð64 6 1Þ meV, whereas effective mass theory (EMT) predicts $62 meV using an effective electron mass of m Ã e ¼ 0:32m 0 , 32 and the static dielectric constant s ¼ 8:39. 33 The small discrepancy is due to the chemical shift, which lowers the ground state of the donor electron. For this reason, we probably slightly overestimate, and EMT underestimates the total donor ionization energy.…”

mentioning

confidence: 99%

Direct determination of the silicon donor ionization energy in homoepitaxial AlN from photoluminescence two-electron transitions

Neuschl

Thonke

Feneberg

et al. 2013

Applied Physics Letters

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We report on the identification of a two-electron transition for the shallow donor silicon in homoepitaxial aluminum nitride (AlN). One c-oriented sample was analyzed by low temperature photoluminescence spectroscopy on multiple excitation spots. We find a unique correlation of one single emission band, 76.6 meV below the free excitonic emission, with the luminescence of excitons bound to neutral silicon proving the identity as a two-electron transition. The assignment is confirmed by temperature dependent photoluminescence investigations. We find a donor ionization energy of ð63:5 6 1:5Þ meV for silicon in AlN. V C 2013 AIP Publishing LLC.Recent interest in light emitting devices operating in the deep UV spectral region 1 is due to promising applications such as the deactivation of microorganisms by exposure to light with short wavelengths. Several research groups are working on light emitting diodes (LEDs) based on aluminum gallium nitride (AlGaN) fabricated on foreign substrates such as sapphire 2-4 or silicon carbide. 5 As a consequence, these structures suffer from high defect densities due to the lattice and thermal expansion coefficient mismatch between the substrate material and the epitaxial film, directly degrading the efficiency of the device. 6 One approach is to deposit the diode layer, with high Al content, directly on an AlN single crystal. This kind of substrate is promising for an improvement of the crystal quality, 7,8 and recently, well operating LEDs 9 and lasers 10,11 have been presented. Nevertheless, many fundamental properties such as the exact electronic structure for typical dopants are not known. Only recently, homoepitaxial AlN layers of good crystal quality became available allowing the proper identification of single bound excitonic emission bands. 12,13 However, for the mostly present donor silicon (Si), there is no agreement on the ionization energy. There is an ongoing discussion, whether Si Al undergoes a strong lattice relaxation and forms a deep DX center, where the dopant atom captures a second electron. Several theoretical studies predict DX center formation for Si Al , 14,15 whereas others find silicon to be a shallow donor in wurtzite AlN. 16,17 Experimentally, the majority of studies shows n-type conductivity after silicon doping, 18-24 although they find very different values for the ionization energy ranging from 86 to 570 meV. On the other hand, there are two detailed reports about DX center formation found by spectrally resolved photoconductivity and electron paramagnetic resonance. 25,26 In this letter, we present a detailed investigation of a homoepitaxially grown wurtzite AlN layer by means of temperature dependent photoluminescence (PL) spectroscopy. Exposure at multiple excitation spots and the temperature dependent behavior of the emission bands observed allow for an identification of a two-electron transition with shallow silicon donors involved. We further discuss the presented results in the framework of possible DX center formation.The sample under investigat...

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“…As proposed earlier [38,39,65], we model the absorption spectra α (E) using Elliot's theory [66,67] α…”

Section: Modeling Of Absorption and Emission Spectramentioning

confidence: 99%

Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

et al. 2017

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We measure temperature-dependent one-photon and two-photon induced photoluminescence from (CH3NH3)PbBr3 single crystals cleaved in ultrahigh vacuum. An approach is presented to extract absorption spectra from a comparison of both measurements. Cleaved crystals exhibit broad photoluminescence spectra. We identify the direct optical band gap of 2.31 eV. Below 200 K the band gap increases with temperature, and it decreases at elevated temperature, as described by the BoseEinstein model. An excitonic transition is found 22 meV below the band gap at temperatures < 200 K. Defect emission occurs at photon energies < 2.16 eV. In addition, we observe a transition at 2.25 eV (2.22 eV) in the orthorhombic (tetragonal and cubic) phase. Below 200 K, the associated exciton binding energy is also 22 meV, and the transition redshifts at higher temperature. The binding energy of the exciton related to the direct band gap, in contrast, decreases in the cubic phase. High-energy emission from free carriers is observed with higher intensity than reported in earlier studies. It disappears after exposing the crystals to air.

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Anisotropic absorption and emission of bulk(11¯00)AlN

Cited by 68 publications

References 61 publications

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Direct determination of the silicon donor ionization energy in homoepitaxial AlN from photoluminescence two-electron transitions

Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

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