A study into the optimal deposition temperature for ultra-thin La2O3/Ge and Y2O3/Ge gate stacks has been conducted in this paper with the aim to tailor the interfacial layer for effective passivation of the Ge interface. A detailed comparison between the two lanthanide oxides (La2O3 and Y2O3) in terms of band line-up, interfacial features, and reactivity to Ge using medium energy ion scattering, vacuum ultra-violet variable angle spectroscopic ellipsometry (VUV-VASE), X-ray photoelectron spectroscopy, and X-ray diffraction is shown. La2O3 has been found to be more reactive to Ge than Y2O3, forming LaGeOx and a Ge sub-oxide at the interface for all deposition temperature studied, in the range from 44 °C to 400 °C. In contrast, Y2O3/Ge deposited at 400 °C allows for an ultra-thin GeO2 layer at the interface, which can be eliminated during annealing at temperatures higher than 525 °C leaving a pristine YGeOx/Ge interface. The Y2O3/Ge gate stack deposited at lower temperature shows a sub-band gap absorption feature fitted to an Urbach tail of energy 1.1 eV. The latter correlates to a sub-stoichiometric germanium oxide layer at the interface. The optical band gap for the Y2O3/Ge stacks has been estimated to be 5.7 ± 0.1 eV from Tauc-Lorentz modelling of VUV-VASE experimental data. For the optimal deposition temperature (400 °C), the Y2O3/Ge stack exhibits a higher conduction band offset (>2.3 eV) than the La2O3/Ge (∼2 eV), has a larger band gap (by about 0.3 eV), a germanium sub-oxide free interface, and leakage current (∼10−7 A/cm2 at 1 V) five orders of magnitude lower than the respective La2O3/Ge stack. Our study strongly points to the superiority of the Y2O3/Ge system for germanium interface engineering to achieve high performance Ge Complementary Metal Oxide Semiconductor technology.

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The effect of iron oxide nanoparticles (Fe2O3 NPs) content on the structural and optical parameters of polyvinyl alcohol/graphene (PVA/G) blend has been investigated. Fe2O3 NPs were synthesized by the hydrothermal procedure. Nanocomposite (NC) films of PVA/G filled with different amounts of Fe2O3 NPs were equipped using the solution casting technique. The surface morphology, structural, and optical properties were examined by scanning electron microscope (SEM), X‐ray diffraction (XRD), and ultraviolet‐visible‐near‐IR (UV‐Vis‐NIR) spectrophotometry techniques, respectively. SEM micrographs reveal the homogenous distribution of Fe2O3 NPs in the PVA/G matrix. The XRD analysis exhibits the formulation of the hematite phase of Fe2O3 NPs and the semi‐crystalline nature of PVA/G NC films. The UV‐Vis‐NIR data analysis shows that the optical properties of the PVA/G blend could be tailored via Fe2O3 NPs filling. Wemple–DiDomenico model is utilized to explore the dispersion parameters of the prepared NCs. A significant effect of Fe2O3 NPs filling is realized on the oscillator and dispersion energies, infinite refractive index, dielectric constant, average oscillator strength and the lattice dielectric constant of the NC films. PVA/G filled Fe2O3 NPs are suggested for different optical and storage applications.

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