Qualitative analysis of the valence and conduction band offset parameters in FeNiO/CuNiO bilayer film using X‐ray photoelectron spectroscopy

AbstractWe report on the chemical deposition and electronic properties of CuInS2/Zn(S,O) interfaces. The Zn(S,O) buffer was grown by a new chemical bath deposition (CBD) process that allows the tailoring of the S/O ratio in the films. Resulting Zn(S,O) films exhibit transparencies above 80% (for λ>390 nm) and an optical energy band gap of 3.9 eV which decreases to 3.6 eV after annealing in air at 200°C. Production line CuInS2 (CIS) absorbers provided by Sulfurcell Solartechnik GmbH are used as substrates for the investigation of the CIS/Zn(S,O) interface and the chemical composition of Zn(S,O). A ZnS/(ZnS+ZnO) ratio of 0.5 is found by X-ray photoelectron spectroscopy and X-ray excited Auger electron spectroscopy (XPS and XAES). The valence band offset between the heterojunction partners (ΔEV = 1.8 ± 0.2 eV) has been determined by means of XPS and ultraviolet photoelectron spectroscopy (UPS). Considering the energy band gap of the CIS absorber and the measured band gap of Zn(S,O), the conduction band offset (ΔEC) is calculated as: resulting in a spike of 0.5±0.3 eV in the conduction band at the heterojunction before annealing. After the heat treatment, the valence band offset is reduced to 1.5±0.2 eV and the calculated conduction band offset remains at 0.5±0.3 eV.

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The Synthesis of NiO/TiO2Heterostructures and Their Valence Band Offset Determination

Journal of Nanomaterials ◽

10.1155/2014/928658 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 8

Author(s):

Z. H. Ibupoto ◽

M. A. Abbasi ◽

X. Liu ◽

M. S. AlSalhi ◽

M. Willander

Keyword(s):

Valence Band ◽

Conduction Band ◽

Photoelectron Spectroscopy ◽

Glass Substrate ◽

Band Offset ◽

Valence Band Offset ◽

X Ray ◽

Conduction Band Offset ◽

P Type ◽

Fto Glass

In this work, a heterojunction based on p-type NiO/n-type TiO2nanostructures has been prepared on the fluorine doped tin oxide (FTO) glass substrate by hydrothermal method. Scanning electron microscopy (SEM) and X-Ray diffraction techniques were used for the morphological and crystalline arrays characterization. The X-ray photoelectron spectroscopy was employed to determine the valence-band offset (VBO) of the NiO/TiO2heterojunction prepared on FTO glass substrate. The core levels of Ni 2p and Ti 2p were utilized to align the valence-band offset of p-type NiO/n-type TiO2heterojunction. The valence band offset was found to be∼0.41 eV and the conduction band was calculated about∼0.91 eV. The ratio of conduction band offset and the valence-band offset was found to be 2.21.

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Experimental and First-Principles Studies of the Band Alignment at the HfO2/4H-SiC (0001) Interface

Materials Science Forum ◽

10.4028/www.scientific.net/msf.527-529.1071 ◽

2006 ◽

Vol 527-529 ◽

pp. 1071-1074 ◽

Cited By ~ 3

Author(s):

Carey M. Tanner ◽

Jong Woo Choi ◽

Jane P. Chang

Keyword(s):

Conduction Band ◽

Photoelectron Spectroscopy ◽

Density Functional ◽

Atomic Layer ◽

Band Alignment ◽

Functional Theory ◽

X Ray ◽

Conduction Band Offset ◽

Mos Devices ◽

Layer Deposition

The electronic properties of HfO2 films on 4H-SiC were investigated to determine their suitability as high-κ dielectrics in SiC power MOS devices. The band alignment at the HfO2/4HSiC interface was determined by X-ray photoelectron spectroscopy (XPS) and supported by density functional theory (DFT) calculations. For the experimental study, HfO2 films were deposited on ntype 4H-SiC by atomic layer deposition (ALD). XPS analysis yielded valence and conduction band offsets of 1.69 eV and 0.75 eV, respectively. DFT predictions based on two monoclinic HfO2/4HSiC (0001) structures agree well with this result. The small conduction band offset suggests the potential need for further interface engineering and/or a buffer layer to minimize electron injection into the gate oxide.

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Impact of Interface Defect Passivation on Conduction Band Offset at SiO2/4H-SiC Interface

Materials Science Forum ◽

10.4028/www.scientific.net/msf.717-720.721 ◽

2012 ◽

Vol 717-720 ◽

pp. 721-724 ◽

Cited By ~ 5

Author(s):

Takuji Hosoi ◽

Takashi Kirino ◽

Atthawut Chanthaphan ◽

Yusuke Uenishi ◽

Daisuke Ikeguchi ◽

...

Keyword(s):

Conduction Band ◽

Photoelectron Spectroscopy ◽

Hydrogen Gas ◽

Band Alignment ◽

Band Offset ◽

Partial Recovery ◽

Conduction Band Offset ◽

Interface Defect ◽

Defect Passivation ◽

Thermally Grown

The change in energy band alignment of thermally grown SiO2/4H-SiC(0001) structures due to an interface defect passivation treatment was investigated by means of synchrotron radiation photoelectron spectroscopy (SR-PES) and electrical characterization. Although both negative fixed charge and interface state density in SiO2/SiC structures were effectively reduced by high-temparature hydrogen gas annealing (FGA), the conduction band offset (ΔEc) at the SiO2/SiC interface was found to be decreased by about 0.1 eV after FGA. In addition, a subsequent vacuum annealing to induce hydrogen desorption from the interface resulted in not only a slight degradation in interface property but also a partial recovery of ΔEc value. These results indicate that the hydrogen passivation of negatively charged defects near the thermally grown SiO2/SiC interface causes the reduction in conduction band offset. Therefore, the tradeoff between interface quality and conduction band offset for thermally grown SiO2/SiC MOS structure needs to be considered for developing SiC MOS devices.

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Band Alignment of CdS/Cu2ZnSnSe4 Heterointerface and Solar Cell Performances

MRS Advances ◽

10.1557/adv.2017.315 ◽

2017 ◽

Vol 2 (53) ◽

pp. 3157-3162 ◽

Cited By ~ 1

Author(s):

Takehiko Nagai ◽

Shinho Kim ◽

Hitoshi Tampo ◽

Kang Min Kim ◽

Hajime Shibata ◽

...

Keyword(s):

Conduction Band ◽

Band Alignment ◽

Photoemission Spectroscopy ◽

Band Offset ◽

Valence Band Offset ◽

X Ray ◽

Heterojunction Solar Cells ◽

Conduction Band Offset ◽

Ultraviolet Photoemission Spectroscopy ◽

Large Spike

ABSTRACTWe determined that the conduction band offset (CBO) and the valence band offset (VBO) at the CdS/ Cu2ZnSnSe4 (CZTSe) heterointerface are +0.56 and +0.89eV, respectively, by using X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and inversed photoemission spectroscopy (IPES). A positive CBO value, so-called “spike” structure, means that the position of conduction band becomes higher than that of absorber layer. The evaluated CBO of +0.56 eV suggests that the conduction band alignment at CdS/CZTSe interface is enough to become an electron barrier. Despite such a large spike structure in the conduction band at the interface, a conversion efficiency of 8.7 % could be obtained for the CdS/CZTSe heterojunction solar cells.

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