Density of states, hybridization, and band-gap evolution in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Al</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:math>alloys

Duda, Laurent; Stagarescu, Cristian; Downes, James E.; Smith, Kevin; Korakakis, D.; Moustakas, T. D.; Guo, Jinghua; Nordgren, Joseph

doi:10.1103/physrevb.58.1928

Cited by 80 publications

(59 citation statements)

References 22 publications

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“…To directly measure the band positions we used the combination of soft x-ray emission (SXE) and absorption (XAS) spectroscopies. XAS and SXE directly probe the partial density of states (DOS) of the conduction band and valence band, respectively [31]. Overlapping the SXE and XAS spectra with reference to the core level provides a direct measurement of the energy positions of the valence and conduction band states in semiconductor materials.…”

Section: Structure Of Lt-mbe Gan 1-x As Xmentioning

confidence: 99%

Highly mismatched crystalline and amorphous GaN1−xAsx alloys in the whole composition range

Новиков

Broesler

et al. 2009

Journal of Applied Physics

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Alloying is a commonly accepted method to tailor properties of semiconductor materials for specific applications. Only a limited number of semiconductor alloys can be easily synthesized in the full composition range. Such alloys are, in general formed of component elements that are well matched in terms of ionicity, atom size and electronegativity. In contrast there is a broad class of potential semiconductor alloys formed of component materials with distinctly different properties. In most instances these mismatched alloys are immiscible under standard growth conditions. Here we report on the properties of GaN 1-x As x a highly mismatched, immiscible alloy system that was successfuly synthesized in the whole composition range using a non-equilibrium low temperature molecular beam epitaxy technique. The alloys are amorphous in the composition range of 0.170.2, and to the upward movement of the valence band for alloys with x<0.2. The unique features of the band structure offers an opportunity of using GaN 1-x As x alloys for various types of solar power conversion devices. 3 1. The Ga-N-As Alloy system Dilute alloysSemiconductor alloys formed through substitution of atoms with very different electronegativity and/or size have been known as highly mismatched alloys (HMAs).Because of large miscibility gaps, typically HMAs consist of a semiconductor matrix (elemental or compound) with the substitution of a small amount (up to several percents) of distinctly different isovalent atoms. The HMAs show large band gap reduction and their electronic structure is drastically different from their host materials. This is in contrast to conventional semiconductor alloys such as AlGaAs and GaAsP whose physical, electronic and optical properties can be deduced from a linear interpolation between their corresponding end point compounds with only a slight deviation, as predicted by the virtual crystal approximation (VCA). A most notable example of HMAs is the As-rich GaN x As 1-x in which strong band gap reduction by as much as 180 meV per mole percent of N has been observed [1,2,3,4]. The strong dependence of the band gap on the N content has made these diluted III-V nitrides important materials for a variety of applications, including long wavelength optoelectronic devices [5,6] and high efficiency hybrid solar cells [7,8].In contrast to the very extensively studied As-rich GaNAs alloys much less work has been devoted to HMAs on the N-rich side of this alloy system. It was found that GaN doped with As at low, impurity like levels shows a characteristic blue emission at room temperature. At higher As doping levels an abrupt decrease in the band gap of...

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Section: Structure Of Lt-mbe Gan 1-x As Xmentioning

confidence: 99%

Highly mismatched crystalline and amorphous GaN1−xAsx alloys in the whole composition range

Новиков

Broesler

et al. 2009

Journal of Applied Physics

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“…A low-energy peak at −17.5 eV ͑enhanced by a factor of 10͒ is due to N 2p-N 2s-Ga 3d hybridization. 8,11 The magnitude of the Rayleigh elastic scattering primarily depends on the surface roughness and the experimental geometry. Note that the elastic scattering ͑enhanced by a factor of 10͒ at the resonant excitation energy ͑402.8 eV͒ is very weak which is a sign of low surface roughness.…”

Section: A N K X-ray Emissionmentioning

confidence: 99%

“…9 and 11͒ and its intensity was found to depend on the Ga content. 8 However, the electronic structure and chemical bonding of N with Ga is still largely unknown in GaN. This includes, in particular, the Ga 4p states at the top of the valence band, the N 2s hybridization with the Ga 4s states at the bottom of the valence band, and the potentially important role of the shallow Ga 3d semicore states.…”

Section: Introductionmentioning

confidence: 99%

“…Soft x-ray absorption ͑SXA͒ and emission ͑SXE͒ spectroscopy employing dipole selection rules has also been applied at the N K edge of GaN. [6][7][8] The top of the valence band in GaN is dominated by N 2p states whereas the Ga 4s states are much weaker and located at somewhat lower energy. SXE of GaN has been utilized at the Ga L 3 edge, but the position and shape of the weak Ga 4s valence states could not be resolved or identified.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure of GaN and Ga investigated by soft x-ray spectroscopy and first-principles methods

et al. 2010

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The electronic structure and chemical bonding of wurtzite-GaN investigated by N 1s soft x-ray absorption spectroscopy and N K, Ga M 1 , and Ga M 2,3 emission spectroscopy is compared to that of pure Ga. The measurements are interpreted by calculated spectra using first-principles density-functional theory ͑DFT͒ including dipole transition matrix elements and additional on-site Coulomb interaction ͑WC-GGA+ U͒. The Ga 4p-N 2p and Ga 4s-N 2p hybridization and chemical bond regions are identified at the top of the valence band between −1.0 and −2.0 and further down between −5.5 and −6.5 eV, respectively. In addition, N 2s-N 2p-Ga 4s and N 2s-N 2p-Ga 3d hybridization regions occur at the bottom of the valence band between −13 and −15 eV, and between −17.0 and −18.0 eV, respectively. A bandlike satellite feature is also found around −10 eV in the Ga M 1 and Ga M 2,3 emission from GaN, but is absent in pure Ga and the calculated ground-state spectra. The difference between the identified spectroscopic features of GaN and Ga are discussed in relation to the various hybridization regions calculated within band-structure methods.

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“…For example, the electron energy-loss near-edge structure or the x-ray absorption near-edge structure of nitrogen K-edges has been used as a ''fingerprint'' to identify the chemical environment of the nitrogen atom, [5][6][7][8][9][10] the phase composition, 11,12 as well as phase orientations. 11,12 In anisotropic wurtzite structures, because of the dipole selection rule, the experimental K-edge spectra are normally composed a mixture of p xy and p z components with a varying ratio determined by the experimental condition.…”

Section: -12mentioning

confidence: 99%

Anisotropic spectroscopy of nitrogen K-edge in group-III nitrides

Gao

Zhang

Zhu

et al. 2004

Applied Physics Letters

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Ab initio calculation of nitrogen K-edges for use in the core-level spectroscopy of industrially important group-III nitrides ͑AlN, GaN, InN͒ has been carried out systematically including the core-hole effect. The theoretical spectra for transition into final states with p x,y and p z symmetries are in good agreement with the available anisotropic electron energy-loss measurements. Our spectra can be used as ''fingerprints'' to characterize the group-III nitrides, for example, not only to distinguish between different polymorphs of group-III nitrides, but also to identify the presence of surface oxidation. We have also presented our simulated results in terms of an orientation-average spectrum and a sample orientation-dependent dichroic spectrum for future reference.

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Density of states, hybridization, and band-gap evolution inAlxGa1−xNalloys

Cited by 80 publications

References 22 publications

Highly mismatched crystalline and amorphous GaN1−xAsx alloys in the whole composition range

Highly mismatched crystalline and amorphous GaN1−xAsx alloys in the whole composition range

Electronic structure of GaN and Ga investigated by soft x-ray spectroscopy and first-principles methods

Anisotropic spectroscopy of nitrogen K-edge in group-III nitrides

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