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In the present paper, we have investigated the structural and electronic properties of Eu2O3 thin film deposited by pulsed laser deposition technique on Si (100) substrate. The film was characterized by X-ray diffraction and photoemission measurements. X-ray photoemission studies suggest that Eu has 2+ (∼8%) and 3+ (∼92%) valence states in the film. Valence band spectrum of the film shows four features (2 eV, 4.8 eV, 7.7 eV, and 10.4 eV) with the prominent one at 7.7 eV due to the Eu3+ (4f 6) state. Resonance photoemission spectroscopy measurements have been performed in the Eu 4d → 4f photo absorption region, and thus, obtained constant initial state intensity plots suggest that the feature close to the Fermi level (∼2 eV) results from the hybridization of the O 2p and Eu2+ (4f7) states, while other features appearing at higher binding energies are due to the hybridization of the O 2p and Eu3+ (4f 6) states. [ABSTRACT FROM AUTHOR]

The valence and conduction band offsets of Zn1-xCd1-xO/ZnO hetero-junctions deposited by pulsed laser deposition technique were estimated by X-ray photoelectron, valence band, and UV-visible spectroscopy. Type-II band alignment (staggered gap) with ratios of conduction band to valence band offsets (ΔEC/ΔEV) was found to be 0.77 and 0.59 for Zn0.95Cd0.05O/ZnO and Zn0.90Cd0.10O/ZnO hetero-structures, respectively, which can be used in longer wavelength regime optoelectronic devices. The higher value of valence band offset as compared to conduction band offset suggests that the transport at interface is mainly due to electrons. [ABSTRACT FROM AUTHOR]

We have probed the electronic structure across the ferroelectric transition temperature (TC = 355 K) of hexagonal Sr0.6Ba0.4MnO3 (SBMO) which shows a magneto-electric effect at room temperature. The valence and conduction bands are characterized by resonant photoemission and X-ray absorption spectroscopy measurements, respectively. The valence band spectrum is found to be hugely modified across TC. Above TC, SBMO behaves like a Mott-Hubbard insulator, whereas at 300 K, it shows a charge-transfer-type insulator behavior. Modulation in the hybridization of Mn-3d and O-2p orbitals due to local structural variations with temperature unravels the rational for the observed electronic structure transition vis a vis magnetic and electrical behaviors of SBMO. [ABSTRACT FROM AUTHOR]

Epitaxial growth of α-Cr2O3(p-type) on c-Al2O3 and β-Ga2O3 (n-type) on α-Cr2O3(p-type) has been carried out to make an all oxide epitaxial n-type β-Ga2O3/p-type α-Cr2O3 heterojunction using RF sputtering. A valence band offset of 3.38 ± 0.2 eV at the heterojunction is determined using Kraut's method. From the bandgap measurements of α-Cr2O3 and β-Ga2O3, the conduction band offset of 1.68 ± 0.2 eV at the heterojunction is obtained. Thus, the band alignment at this heterojunction is found to be staggered (Type-II), which leads to the confinement of electrons and holes in the β-Ga2O3 layer and α-Cr2O3 layer, respectively. Our results provide a pathway to design all oxide optoelectronic devices based on a p-n heterojunction consisting of n-type β-Ga2O3 and p-type α-Cr2O3. [ABSTRACT FROM AUTHOR]

Electronic structures modification of polycrystalline LuFe2O4 across 3 dimensional to 2 dimensional charge ordering (CO) has been studied by resonance photoemission spectroscopy. Constant-initialstate spectra measured across 3p→3d resonance energy indicate its charge transfer insulating behavior. Valance band spectra study shows states lying closer to the Fermi level are due to Fe2+ ions. As the temperature is varied from 3D to 2D CO state, a weight transfer of DOS from low binding energy to higher binding energy is observed which is attributed to the modification in the Fe- O hybridized states. [ABSTRACT FROM AUTHOR]

We report the change in the type of band alignments due to an increase in the dopant (Mg) concentration in pulsed laser deposited ZnO/MgZnO bilayer film. The band offset measurements were carried out from the core level shifts as well as valence band maxima in the single as well as the bilayer films. The change in the type of band alignment is attributed to the surface enrichment of Mg at the heterojunction. [ABSTRACT FROM AUTHOR]

Valence band spectra (VBS) and its modification across Curie temperature (TC) of Sr2CoO4 thin film are studied using resonant photoemission spectroscopy. It is found that VBS mainly consists of hybridized states of Co-3d t2geg and O-2p; however, Co-3d eg states show its prominence only in the ferromagnetic temperature regime. Below TC, spectral weight transfer takes place anomalously from high binding energy (B.E.) region to low B.E. region, signifying the enhanced intermediate or low spin state Co4+ ions. It is suggested that spin-lattice coupling and many-body effects in Sr2CoO4 derived from the strong electron correlations lead to such temperature dependence of VBS. [ABSTRACT FROM AUTHOR]

Synchrotron based photoemission spectroscopy study shows a type-II band alignment at pulsed laser deposited epitaxial ZnO layer and GaP substrate. Additionally, the ZnO/GaP hetero-junction is comprised of an interfacial GaOx layer. Valence band onsets corresponding to ZnO, GaOx, and GaP materials enabled us to determine the valence band offset (DEV) values of 2.81 eV, 0.35 eV, and 2.46 eV at ZnO/GaP, ZnO/GaOx, and GaP/GaOx hetero-junctions, respectively. ΔEV values determined directly from the difference of valence band onsets are in corroboration with that obtained by Kraut's method. The band alignment and interface study of ZnO/GaP hetero-junction can be used to design optoelectronic devices. [ABSTRACT FROM AUTHOR]

Electronic structure of pulsed laser deposited hexagonal-YMnO3 film on Al2O3 (0001) substrate has been investigated by photoemission spectroscopy using variable energy photon sources. Resonance photoemission results reveal the charge transfer nature of h-YMnO3 and variation in strength of hybridization between oxygen 2p and Mn 3d across the valence band region. The valence states sensitive to lattice distortion (inversion asymmetry) demonstrate the evolution of spin orbit interaction (SO). This SO along with its anisotropic behavior is well identified by the constant initial state plots. [ABSTRACT FROM AUTHOR]

Valence band spectra (VBS) and its modification across Curie temperature (TC) of Sr2CoO4 thin film are studied using resonant photoemission spectroscopy. It is found that VBS mainly consists of hybridized states of Co-3d t2geg and O-2p; however, Co-3d eg states show its prominence only in the ferromagnetic temperature regime. Below TC, spectral weight transfer takes place anomalously from high binding energy (B.E.) region to low B.E. region, signifying the enhanced intermediate or low spin state Co4+ ions. It is suggested that spin-lattice coupling and many-body effects in Sr2CoO4 derived from the strong electron correlations lead to such temperature dependence of VBS. [ABSTRACT FROM AUTHOR]

We have probed the electronic structure across the ferroelectric transition temperature (TC = 355 K) of hexagonal Sr0.6Ba0.4MnO3 (SBMO) which shows a magneto-electric effect at room temperature. The valence and conduction bands are characterized by resonant photoemission and X-ray absorption spectroscopy measurements, respectively. The valence band spectrum is found to be hugely modified across TC. Above TC, SBMO behaves like a Mott-Hubbard insulator, whereas at 300 K, it shows a charge-transfer-type insulator behavior. Modulation in the hybridization of Mn-3d and O-2p orbitals due to local structural variations with temperature unravels the rational for the observed electronic structure transition vis a vis magnetic and electrical behaviors of SBMO. [ABSTRACT FROM AUTHOR]