Surface plasmons at MOCVD-grown GaN

Polyakov, V. M.; Tautz, F. Stefan; Sloboshanin, S.; Schaefer, J. A.; Usikov, A. S.; Ber, B.Ja.

doi:10.1088/0268-1242/13/12/011

Cited by 20 publications

(11 citation statements)

References 30 publications

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“…These values were consistent with other group's results for Ga-face GaN (0.3-1.5 eV) 13,[25][26][27] and Nface GaN (0.1-1.0 eV). [28][29][30] Fig. 3 shows a schematic of the surface band bending of Ga-and N-face GaN after in-situ NH 3 plasma treatment, where the Ga-and N-face GaN exhibited upward bending of 0.8 6 0.1 eV and 0.6 6 0.1 eV, respectively.…”

Section: Resultsmentioning

confidence: 99%

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Yang

Eller

Nemanich

2014

Journal of Applied Physics

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The effects of surface pretreatment, dielectric growth, and post deposition annealing on interface electronic structure and polarization charge compensation of Ga-and N-face bulk GaN were investigated. The cleaning process consisted of an ex-situ wet chemical NH 4 OH treatment and an in-situ elevated temperature NH 3 plasma process to remove carbon contamination, reduce oxygen coverage, and potentially passivate N-vacancy related defects. After the cleaning process, carbon contamination decreased below the x-ray photoemission spectroscopy detection limit, and the oxygen coverage stabilized at $1 monolayer on both Ga-and N-face GaN. In addition, Ga-and N-face GaN had an upward band bending of 0.8 6 0.1 eV and 0.6 6 0.1 eV, respectively, which suggested the net charge of the surface states and polarization bound charge was similar on Ga-and N-face GaN. Furthermore, three dielectrics (HfO 2 , Al 2 O 3 , and SiO 2 ) were prepared by plasma-enhanced atomic layer deposition on Ga-or N-face GaN and annealed in N 2 ambient to investigate the effect of the polarization charge on the interface electronic structure and band offsets. The respective valence band offsets of HfO 2 , Al 2 O 3 , and SiO 2 with respect to Ga-and N-face GaN were 1.4 6 0.1, 2.0 6 0.1, and 3.2 6 0.1 eV, regardless of dielectric thickness. The corresponding conduction band offsets were 1.0 6 0.1, 1.3 6 0.1, and 2.3 6 0.1 eV, respectively. Experimental band offset results were consistent with theoretical calculations based on the charge neutrality level model. The trend of band offsets for dielectric/GaN interfaces was related to the band gap and/or the electronic part of the dielectric constant. The effect of polarization charge on band offset was apparently screened by the dielectric-GaN interface states. V C 2014 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 99%

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Yang

Eller

Nemanich

2014

Journal of Applied Physics

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“…The frequency of these two coupled modes have been obtained by solving the equation ε(ω)=-1, where ε(ω) is the total dielectric function of the semiconductor in the presence of the free carriers (Lorentz oscillator and Drude model). With the application of inelastic electron scattering by using HREELS the free carrier concentration for homogeneously and δ-doped samples MBE grown of GaAs (001) [20] have been determined as well as for GaN [21]. In addition, with dipole scattering theory by using self-consistent electron density profiles it was possible to calculate the surface energy loss function and hence the expected energy loss spectra.…”

Section: Resultsmentioning

confidence: 99%

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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“…Especially the band bending shows significant differences between both polar surfaces 4 and published values show a large variation. For Ga‐face an upward band bending between 0.3 and 1.5 eV 4–6 was found and the values for N‐face vary between a small downward band bending 2 to a strong upward band bending 7. However, the value in the literature tends to a band bending of about 0.4 eV for contamination‐free Ga‐face GaN 8.…”

Section: Introductionmentioning

confidence: 92%

“…The band bending can be determined by different methods e.g. photoelectron spectroscopy 8, high resolution electron energy loss spectroscopy 7, photoelectron emission microscopy 2, Kelvin probe 12, surface potential electric force microscopy 13, spectroscopic ellipsometry 9 and electrical measurements 4. Within this work both contamination free polar surfaces, the (0001) (Ga‐face) and the (000‐1) orientation (N‐face) of GaN were studied with photoelectron spectroscopy (XPS and UPS) and high resolution electron energy loss spectroscopy (HREELS).…”

Section: Introductionmentioning

confidence: 99%

Analysis of polar GaN surfaces with photoelectron and high resolution electron energy loss spectroscopy

Lorenz

Haensel

Gutt

et al. 2010

phys. stat. sol. (b)

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The properties of Ga-face and N-face GaN surfaces were studied by X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS), atomic force microscopy (AFM), reflection high energy electron diffraction (RHEED) as well as high resolution electron energy loss spectroscopy (HREELS). The Ga-face GaN was grown on 6H-SiC(0001) and the N-face GaN directly on alpha-Al2O3(0001) by plasma assisted molecular beam epitaxy (PAMBE) and in situ analysed by photoelectron spectroscopy. The Ga-face GaN surfaces show a 2 x 2 reconstruction measured by RHEED. From the analysis of the XPS spectra a valence band maximum located 2.9 eV below the Fermi level results. Furthermore, the UPS spectra exhibit two surface states. The N-face GaN presented a 1 x 1 surface with one surface state and a valence band maximum located 2.4 eV below E-F. These values correspond to an upward band bending of about 0.9 eV for the N-face GaN(000 (1) over bar)-1 x 1 and about 0.4 eV for the GaN(0001)-2 x 2 (Ga-face) results. The different surface band bending is further supported by the evaluation of the FWHM of the quasi-elastically reflected electrons in HREELS

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Surface plasmons at MOCVD-grown GaN

Cited by 20 publications

References 30 publications

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

HREELS study of graphene formed on hexagonal silicon carbide

Analysis of polar GaN surfaces with photoelectron and high resolution electron energy loss spectroscopy

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