Electron‐phonon‐plasmon interaction in MBE‐grown indium nitride – A high resolution electron energy loss spectroscopy (HREELS) study

Kloeckner, K.; Himmerlich, Marcel; Koch, Roland; Polyakov, V. M.; Eisenhardt, Anja; Haensel, Thomas; Ahmed, S.I.-U.; Krischok, S.; Schaefer, J.A.

doi:10.1002/pssc.200982494

Cited by 9 publications

(4 citation statements)

References 16 publications

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“…Instead, a twolevel structure appears at ω + =1050 cm -1 (130 meV) with a Fano-type shape and ω -= 430 cm -1 (53 meV) above and below the energy of the Fuchs-Kliewer surface optical phonon at 945 cm -1 (117 meV). This situation is quite similar to observations in the case of InN, where an accumulation layer is present in the space charge regime [14]. We identify this 2-peak structure with the coupling of the FKphonons from the SiC-substrate with the collective motion of the conduction electrons (plasmons), which are provided by the graphene layer on top of silicon carbide.…”

Section: Methodssupporting

confidence: 63%

HREELS study of graphene formed on hexagonal silicon carbide

Koch

Haensel

Ahmed

et al. 2010

Phys. Status Solidi (c)

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Using high resolution electron energy loss spectroscopy (HREELS) in conjunction with low energy electron diffraction (LEED) and X‐ray induced photoelectron spectroscopy (XPS), we have studied surface reconstructions from Si‐rich to C‐rich surfaces up to graphene formation. It is shown that the coupling between the longitudinal optical phonons and the carrier plasmons that originate from the presence of the layered semimetallic character of graphene and few layer graphene (FLG) drastically influence the HREELS‐spectra. For the hydrogen smoothened SiC‐samples, which have been subsequently annealed under high Ar‐pressure [1], the Fuchs‐Kliewer surface phonon ω0 is completely screened and two other losses ω‐ and ω+, called plasmarons, appear. They originate from the coupling between surface optical phonons and plasma oscillations of free‐electrons resulting from the graphene/SiC interface. For the heated SiC‐samples under ultra‐high‐vacuum (UHV) conditions, the situation is different, which indicates cluster formation of graphene / graphite at the surface. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Methodssupporting

confidence: 63%

HREELS study of graphene formed on hexagonal silicon carbide

Koch

Haensel

Ahmed

et al. 2010

Phys. Status Solidi (c)

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“…The interaction between plasmon and phonon mediates the carrier lattice energy exchanges and thus plays a very important role in the transport properties of Ⅲ-Ⅴ semiconductors. 88 Resonant Raman spectroscopy studies of heavily doped Ⅲ-Ⅴ semiconductors, 85,88 such as GaAs and InN, thin film suggest that the electrostatic coupling of polarized longitudinal optical (LO) phonons with the surrounding charge carriers (plasmons) result in the formation of the so-called L + and L − coupled phonon-plasmon modes. The plasmon-phonon coupling is maximized when the LO phonons resonate with the plasmons.…”

Section: Plasmon-phonon Interactionmentioning

confidence: 99%

Plasmon-induced carrier polarization in semiconductor nanocrystals

et al. 2018

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Spintronics and valleytronics are emerging quantum electronic technologies that rely on using electron spin and multiple extrema of the band structure (valleys), respectively, as additional degrees of freedom. There are also collective properties of electrons in semiconductor nanostructures that potentially could be exploited in multifunctional quantum devices. Specifically, plasmonic semiconductor nanocrystals offer an opportunity for interface-free coupling between a plasmon and an exciton. However, plasmon-exciton coupling in single-phase semiconductor nanocrystals remains challenging because confined plasmon oscillations are generally not resonant with excitonic transitions. Here, we demonstrate a robust electron polarization in degenerately doped InO nanocrystals, enabled by non-resonant coupling of cyclotron magnetoplasmonic modes with the exciton at the Fermi level. Using magnetic circular dichroism spectroscopy, we show that intrinsic plasmon-exciton coupling allows for the indirect excitation of the magnetoplasmonic modes, and subsequent Zeeman splitting of the excitonic states. Splitting of the band states and selective carrier polarization can be manipulated further by spin-orbit coupling. Our results effectively open up the field of plasmontronics, which involves the phenomena that arise from intrinsic plasmon-exciton and plasmon-spin interactions. Furthermore, the dynamic control of carrier polarization is readily achieved at room temperature, which allows us to harness the magnetoplasmonic mode as a new degree of freedom in practical photonic, optoelectronic and quantum-information processing devices.

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“…Besides the bulk also the surface properties are of great importance, due to the existence of an intrinsic surface electron accumulation layer that influences the electronic properties of InN 4, 5. It is assumed that local donor‐type states contribute to the high electron concentration 6–8. Ozone‐induced oxidation of InN reveals that oxygen surface bonds seem to have a passivating effect leading to partial neutralization of donor‐type surface states and a reduction of the electron concentration at the InN surface 9, 10.…”

Section: Introductionmentioning

confidence: 99%

Changes in the valence band structure of as‐grown InN(0001)‐2 × 2 surfaces upon exposure to oxygen and water

Eisenhardt

Reiß

Himmerlich

et al. 2010

Physica Status Solidi (a)

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We investigated the surface chemistry and valence band (VB) structure of as-grown thin InN(0001)-2 Â 2 films as well as their change upon the exposure to oxygen and water. The InN films were grown by plasma-assisted molecular beam epitaxy (PAMBE) and in situ characterized by reflection high electron energy diffraction (RHEED) and photoelectron spectroscopy (UPS, XPS). The oxygen and water exposure was directly performed on the as-grown, contamination-free InN surfaces at room temperature and leads to changes in the chemical surface states as well as the electronic properties. For 2 Â 2 reconstructed InN surfaces one observes directly after growth a surface state at the Fermi-edge which decreases continuously with oxygen and water exposure. Furthermore, two oxygen related electronic states develop in the VB at binding energies at around 5 and 10 eV. For water exposure a third weak state around 8 eV is additionally observed. The impact of oxygen and water on the work function F as well as the variation of surface band bending was investigated. In both cases for initially 2 Â 2 reconstructed surfaces a reduction in the downward band bending is found, while F increases in the case of oxygen exposure but in the case of interaction with water a reduced work function is observed. The oxygen uptake rates reveal a higher reactivity of water with InN surfaces compared to oxygen. Furthermore, during oxidation and water exposure different chemical oxygen bonds are formed, but a direct assignment to In-O or N-O bonds is difficult due to changes in the In3d and N1s XPS core level peak shape.

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Electron‐phonon‐plasmon interaction in MBE‐grown indium nitride – A high resolution electron energy loss spectroscopy (HREELS) study

Cited by 9 publications

References 16 publications

HREELS study of graphene formed on hexagonal silicon carbide

HREELS study of graphene formed on hexagonal silicon carbide

Plasmon-induced carrier polarization in semiconductor nanocrystals

Changes in the valence band structure of as‐grown InN(0001)‐2 × 2 surfaces upon exposure to oxygen and water

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