Quantitative study of molecular<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>trapped in disordered GaN:O films

Ruck, B. J.; Koo, Annette; Lanke, U. D.; Budde, F.; Granville, S.; Trodahl, H. J.; Bittar, A.; Metson, James B.; Kennedy, J.; Markwitz, A.

doi:10.1103/physrevb.70.235202

Cited by 37 publications

(34 citation statements)

References 31 publications

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“…The sharp peak at 401 eV and subsequent structure corresponds to the absorption by molecular nitrogen into the N 2 π* state with the higher vibrational states being clearly identifiable. This has previously been noted in ion-assisted deposition of GaN films [6]. The presence of trapped molecular N 2 is further confirmed by examining the RXES measurements carried out on the Ga 0.8 Mn 0.2 N shown in Fig.…”

Section: Methodssupporting

confidence: 61%

Resonant soft X‐ray emission and X‐ray absorption studies on Ga_1‐xMn_xN grown by pulsed laser deposition

Krishnamurthy

Kennedy

McGee

et al. 2011

Phys. Status Solidi C

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In this study thin film samples of Ga1‐xMnxN were grown by pulsed laser deposition on Al2O3 (0001) substrates. X‐ray diffraction measurements have confirmed these thin films exhibit hexagonal wurtzite structure. SQUID measurements show room temperature ferromagnetism of these dilute magnetic semiconductors (DMS). The techniques of X‐ray absorption and soft X‐ray emission spectroscopy at the N K‐edge were used to study the changes in the unoccupied and occupied N 2p partial density of states respectively as a function of dopant concentration. These element and site specific spectroscopies allow us to characterise the electronic structure of these doped materials and reveal the influence of the Mn doping on the valence band as measured through the N 2p partial density of states. X‐ray absorption measurements at the Mn L‐edge confirm significant substitutional doping of Mn into Ga‐sites. Finally, measurements of heavily Mn‐doped films using both soft X‐ray absorption and resonant soft X‐ray emission at the N K edge reveal the presence of trapped molecular nitrogen. The trapped molecular nitrogen may be due to the high instantaneous deposition rate in the PLD process for these samples (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Methodssupporting

confidence: 61%

Resonant soft X‐ray emission and X‐ray absorption studies on Ga_1‐xMn_xN grown by pulsed laser deposition

Krishnamurthy

Kennedy

McGee

et al. 2011

Phys. Status Solidi C

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“…The films consist of predominantly tetrahedrally (sp 3 ) bonded Ga and N atoms, with oxygen substituted for N in a-GaN:O. In all of the films there are N 2 molecules that we believe to be trapped in interstitial positions, and their density is enhanced when O is present [6].…”

Section: Methodsmentioning

confidence: 97%

SEM and Raman studies of annealed nanocrystalline GaN and amorphous GaN:O

Trodahl¹,

Grigorescu²,

Bittar³

et al. 2006

Journal of Non-Crystalline Solids

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“…The spectrum of sample EuN AS bulk displays the same main features as that of sample EuN NSLS bulk , but with an additional narrow peak near 400 eV that is most likely associated with molecular nitrogen trapped within the films, as seen also in disordered GaN films. 60 Sample EuN AS N2 , grown without direct exposure to the ion source, exhibits the same main spectral features as EuN AS bulk and EuN NSLS bulk , but with substantially worse signal to noise ratio due to the minimal incorporation of nitrogen into this film. Sample EuN AS thin shows a less structured XAS with a single broad peak near 404 eV rather than the clearly identifiable t 2g and e g peaks seen in samples EuN AS bulk and EuN NSLS bulk .…”

Section: B Xas/xps Analysis Of Sample Qualitymentioning

confidence: 96%

Electronic structure of EuN: Growth, spectroscopy, and theory

et al. 2011

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We present a detailed study of the electronic structure of europium nitride (EuN), comparing spectroscopic data to the results of advanced electronic structure calculations. We demonstrate the epitaxial growth of EuN films, and show that in contrast to other rare-earth nitrides successful growth of EuN requires an activated nitrogen source. Synchrotron-based x-ray spectroscopy shows the samples contain predominantly Eu 3+ , but with a small and varying quantity of Eu 2+ that we associate with defects, most likely nitrogen vacancies. X-ray absorption and x-ray emission spectroscopies (XAS and XES) at the nitrogen K-edge are compared to several different theoretical models, namely LSDA+U (local spin density functional theory with Hubbard U corrections), dynamic mean field theory in the Hubbard-I approximation, and QSGW (quasiparticle self-consistent GW ) calculations. The DMFT and QSGW models capture better the density of conduction band states than LSDA+U . Only the Hubbard-I model contains a correct description of the Eu 4f atomic multiplets and locates their energies relative to the band states, and we see some evidence in XAS for hybridization between the conduction band and the the lowest lying 8 S multiplet. The Hubbard-I model is also in good agreement with purely atomic mutliplet calculations for the Eu M-edge XAS. LSDA+U and DMFT find a metallic ground state, while QSGW predicts a direct band gap at X for EuN of about 0.9 eV that matches closely an absorption edge seen in optical transmittance at 0.9 eV and a smaller indirect gap. Overall, the combination of theoretical methods and spectroscopies provides insights into the complex nature of the electronic structure of this material. The results imply that EuN is a narrow band-gap semiconductor that lies close to the metal-insulator boundary, where the close proximity to the Fermi level of an empty Eu 4f multiplet raises the possibility of tuning both the magnetic and electronic states in this system.

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Quantitative study of molecularN2trapped in disordered GaN:O films

Cited by 37 publications

References 31 publications

Resonant soft X‐ray emission and X‐ray absorption studies on Ga_1‐xMn_xN grown by pulsed laser deposition

Resonant soft X‐ray emission and X‐ray absorption studies on Ga_1‐xMn_xN grown by pulsed laser deposition

SEM and Raman studies of annealed nanocrystalline GaN and amorphous GaN:O

Electronic structure of EuN: Growth, spectroscopy, and theory

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Quantitative study of molecularN2trapped in disordered GaN:O films

Cited by 37 publications

References 31 publications

Resonant soft X‐ray emission and X‐ray absorption studies on Ga1‐xMnxN grown by pulsed laser deposition

Resonant soft X‐ray emission and X‐ray absorption studies on Ga1‐xMnxN grown by pulsed laser deposition

SEM and Raman studies of annealed nanocrystalline GaN and amorphous GaN:O

Electronic structure of EuN: Growth, spectroscopy, and theory

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Product

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Resonant soft X‐ray emission and X‐ray absorption studies on Ga_1‐xMn_xN grown by pulsed laser deposition

Resonant soft X‐ray emission and X‐ray absorption studies on Ga_1‐xMn_xN grown by pulsed laser deposition