Electronic structure of Ga1−xCrxN investigated by photoemission spectroscopy

Kim, Jungjin J.; Makino, Hisao; Yamazaki, K.; Ino, A.; Namatame, H.; Takeuchi, Masaki; Hanada, Takuya; Cho, M. W.; Yao, Takafumi

doi:10.1016/j.cap.2004.01.028

Cited by 5 publications

(9 citation statements)

References 15 publications

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“…Binding energies of Cr 2p 3/2 and 2p 1/2 are obtained at 575.7 and 586.4 eV, respectively, which are close to those of the reported CrN [17], indicating 3þ Cr atoms in the GaCrN. This means that the doped Cr atoms are occupying in Ga sites, which is in agreement with the earlier reports [7,18]. The core-level peaks displayed in panels (b) and (c) are shifted upward in the GaCrN:Si as compared to the GaCrN, indicating that the Si doping causes an upward shift of the chemical potential μ [14].…”

Section: Resultssupporting

confidence: 91%

“…Ga 1À x Cr x N has been theoretically predicted to be ferromagnetic via double exchange (DE) mechanism [3] and the FM above room temperature has been experimentally observed [4,5]. The strong hybridization between the Cr 3d states and the valence p band [6] and the formation of Cr 3d derived states within the band gap of GaN [7] have been revealed by X-ray absorption and photoemission studies, suggesting a high potential as an intrinsic DMS. However, the high resistivity and the absence of density of states at Fermi level (E F ) [8] have cast doubt on the DE mechanism of the FM in Ga 1À x Cr x N. On the other hand, the nano-clusters of the Cr atoms embedded in the host semiconductor based on the results of extensive density-functional studies have been proposed to result in the magnetism of the experimental observation [9].…”

Section: Introductionmentioning

confidence: 94%

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Effects of Si-doping on magnetic properties of Ga1−xCrxN

Zhou

Yang

Liu

2015

Journal of Magnetism and Magnetic Materials

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 94%

Effects of Si-doping on magnetic properties of Ga1−xCrxN

Zhou

Yang

Liu

2015

Journal of Magnetism and Magnetic Materials

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“…One can clearly see that Cr 3d-derived emission is seen mostly within the band gap of GaN as reported in Refs. [5,6]. Also the existence of Cr-related states at ∼340 meV above the valence-band maximum (VBM) was reported in Ref.…”

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confidence: 98%

Electronic structure ofGa1−xCrxNand Si-doping effects studied by photoemission and x-ray absorption spectroscopy

et al. 2008

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The electronic structure of the magnetic semiconductor Ga1−xCrxN and the effect of Si doping on it have been investigated by photoemission and soft x-ray absorption spectroscopy. We have confirmed that Cr in GaN is predominantly trivalent substituting for Ga, and that Cr 3d states appear within the band gap of GaN just above the N 2p-derived valence-band maximum. As a result of Si doping, downward shifts of the core levels (except for Cr 2p) and the formation of new states near the Fermi level were observed, which we attribute to the upward chemical potential shift and the formation of a small amount of Cr 2+ species caused by the electron doping. Possibility of Cr-rich cluster growth by Si doping are discussed based on the spectroscopic and magnetization data.

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“…Similar features have been reported for GaN with Cr doping. 29 The modifications of intensity, observed with substantial addition of Ni, are associated with possible factors, such as variation in valence and alternation of the crystalline domains down to the nanoscale.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Understanding Local Bonding Structures of Ni-Doped Chromium Nitride Coatings through Synchrotron Radiation NEXAFS Spectroscopy

et al. 2014

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CrN has widespread applications as protective coatings, for example, in aircraft jet engines whereby their high hardness and good oxidation resistance render metal components resistant to harsh operating conditions. Alloying elements are commonly incorporated (doped) into the coatings to further enhance their thermomechanical properties. However, the effect of dopants on the electronic properties and their roles in modifying the grain boundary configurations remain unclear. Lack of such critical knowledge has hindered the development of design strategies for high performance CrNbased coatings. To address this challenging issue, in the present study nearedge X-ray absorption fine structure (NEXAFS) investigations of Cr 1−y Ni y N coatings at the Cr L 3,2 -edge (570−610 eV), Ni L 3,2 -edge (840−890 eV), and N K-edge (380−450 eV) regions were conducted using synchrotron radiation soft X-ray (SXR) spectroscopy in both Auger electron yield (AEY) and total fluorescence yield (TFY) modes. The chemical states in CrNiN were found to change with the increase of Ni content, manifested as a small chemical shift and moderate change of shapes of various absorption edges. The CrN grain size also became smaller with increasing Ni concentration. These findings help improve our understanding of local bonding structures, which could potentially lead to improved coating designs for highly demanding applications. ■ INTRODUCTIONInterests in transition metal nitrides have risen in the past few years due to their unique physical and mechanical properties that render them suitable for a wide range of technological applications in numerous devices. 1−13 For their superior strength, high corrosion, and oxidation resistance, these materials have been used in extreme pressure and temperature conditions, e.g., jet engine components. Moreover, dopants have been used to enhance their various physicochemical and mechanical properties such as hardness, oxidation resistance, inertness, diffusion resistance, and reflectance by the formation of dislocations, disorderness, vacancy, and atom substitution. 1,[3][4][5]9 In addition, incorporation of Si, Al, or Ti into the CrN matrix results in the reduction of grain sizes down to the nanoscale, which enhances the hardness of the thin films. 2 At the nanoscale, the formation of dislocations becomes difficult, and the hardness of the thin coatings is thereby controlled by the grain boundary. 14 Synchrotron radiation is emitted by very high-energy electrons circulating around a storage ring by a series of magnets separated by straight sections inside the synchrotron tunnels. Owing to their large skin depth in materials,

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Electronic structure of Ga1−xCrxN investigated by photoemission spectroscopy

Cited by 5 publications

References 15 publications

Effects of Si-doping on magnetic properties of Ga1−xCrxN

Effects of Si-doping on magnetic properties of Ga1−xCrxN

Electronic structure ofGa1−xCrxNand Si-doping effects studied by photoemission and x-ray absorption spectroscopy

Understanding Local Bonding Structures of Ni-Doped Chromium Nitride Coatings through Synchrotron Radiation NEXAFS Spectroscopy

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