X-ray photoelectron spectroscopy analysis and band offset determination of CeO₂deposited on epitaxial (100), (110), and (111)Ge

Abstract

The oxidation states, interface, and band alignment properties of physical vapor deposited CeO 2 films on epitaxial (100), (110), and (111)Ge were investigated by x-ray photoelectron spectroscopy (XPS). The cross-sectional transmission electron microscopy demonstrated the polycrystalline nature of the CeO 2 film. XPS analysis showed multiple Ce3d and Ce4d oxidation states with a mixture of Ce 3þ and Ce 4þ components existing in CeO 2 . Angular resolved XPS investigations indicate that the CeO 2 films mostly consist of Ce 4þ oxidation states while the Ce 3þ oxidation states are preferentially present near the surface. The CeO 2 /(100)Ge, CeO 2 /(110)Ge, and CeO 2 /(111)Ge structures showed almost identical valence band offset (VBO) values of 1.6, 1.5, and 1.6 eV, respectively, using XPS measurements from Ce3d core level (CL) peaks. These (VBO) values were also supported by XPS measurements from shallow Ce4d CL binding energy peaks. The conduction band offset values between CeO 2 /Ge were $1.3 eV using the measured optical bandgap of CeO 2 . The XPS spectral analysis of cerium oxidation states and the measured band offset parameters for carrier confinement would offer an important path for the future design of Ge-based metal-oxide semiconductor devices.

Structural, chemical and optical properties of cerium dioxide film prepared by atomic layer deposition on TiN and Si substrates

“…A Ce2O3-like phase cannot be in principle excluded, but we do not have indication of Ce2O3 phase in the diffraction profiles, even in films annealed at high temperature. [18,42,43,44]. The analysis of the Ce 3d spectrum is particularly complex since the deconvolution considers 5 different doublets related to the two oxidation states due to primary photoionization and shake-down satellites: three related to the Ce 4+ doublets and the other two related to the Ce 3+ doublets.…”

“…CeO2 deposition is achieved by using a variety of growth techniques, such as e-beam [11], physical vapor deposition [12], RF-magnetron sputtering [13], chemical vapor deposition (CVD) [14,15 ,16 ,17 ,18], even in sub-stoichiometric form (CeO2-x, 0<x<0.4) [19]. However, when highly stoichiometric oxide is required, atomic layer deposition (ALD) is the most suitable technique.…”

Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates: Structural and Chemical Properties

“…For catalytic applications CeO2 has to be grown on metallic substrates, but few studies exist on cerium oxide film deposited on metals and most of them have the aim to depict the epitaxial growth [6 and references therein]. CeO2 deposition is achieved by using a variety of growth techniques [7,8,9,10]. When highly stoichiometric oxide is required, atomic layer deposition (ALD) is the most suitable technique.…”

Growth, strain relaxation properties and high-κ dielectric integration of mixed-anion GaAs1-ySby metamorphic materials

“…In this regard, key considerations for selecting high-j dielectric materials on GaAs 1-y Sb y active channel layer are the valence band and conduction band offsets >1 eV in order to minimize the carrier injection from the semiconductor into the insulator. 21 As a result, the integration of different high-j dielectrics on GaAs 1-y Sb y (y > 60%) as well as an understanding of the interfacial properties are vital for advancing further development of TFET devices for low-power implantable devices. Moreover, the research of different high-j dielectric materials on GaAs 1-y Sb y can also provide information for future studies on the utilization and suitability of GaAs 1-y Sb y (y > 60%) material systems in multifunctional device applications.…”

“…As shown in Fig. 5, XPS spectra were collected from three samples of each high-j dielectric material: (1) 21 Compensation of the charging by an electron flood source was used in all measurements in order to minimize the binding energy shift. Additionally, the measured CLs and VBM binding energy values were corrected by shifting the measured carbon 1s CL peak to 285.0 eV.…”