Papers by Keyword: XPS

Abstract: In this paper, we study high-temperature H₂, N₂, and H₂/N₂ surface conditioning processes prior to the SiO₂ deposition as a promising approach for SiO₂/4H-SiC interface preparation in metal-oxide-semiconductor field-effect transistors (MOSFET). A thorough electrical analysis is presented, consisting of temperature-dependent transfer characteristics as well as reliability studies regarding bias temperature instabilities (BTI) and dielectric breakdown behavior. Especially N₂-containing surface pretreatments were found to greatly suppress electron traps, whereas hole trapping is enhanced. Finally, X-ray photoelectron spectroscopy (XPS) was utilized to elucidate the elemental surface composition after the different annealing procedures. The obtained results are in good agreement with the electrical characterization and complement already published results regarding the formation of surface reconstructions on 4H-SiC through H₂ and H₂/N₂ annealings.

Abstract: Magnesium Oxide (MgO) thin films were deposited on SiO₂/Si substrate by electron beam evaporation. The properties of MgO thin film with and without oxygen partial pressure have been investigated by X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), and Ultra-Violet Photoemission Spectroscopy (UPS). The XPS was used to investigate the chemical state of the film. REELS spectra revealed that MgO thin films deposited under oxygen partial pressure had band gaps of 6.07 eV. Meanwhile, the band gap for MgO thin films grown without oxygen partial pressure was 7.17 eV. The UPS results showed that the work functions of MgO thin film with and without oxygen partial pressure are 4.75 and 4.84 eV, respectively. In the MgO thin film with oxygen partial pressure, the intensity for the valence band peak at 12.16 eV decreased, but the work function remained relatively the same. Our results demonstrated that the oxygen partial pressure played a crucial role in improving the electronic properties of MgO thin films.

Abstract: The oxygen functional group limits the performance of graphene oxide (GO). By raising the Carbon/Oxygen (C/O) ratio, reducing the oxygen functional group may enhance thermal stability. The effects of the (C/O) ratio of graphene derivatives on the structure-properties relationship in metallocene linear low-density polyethylene (PE), homo polypropylene (PP), and blends thereof were investigated in this research. Using reduced graphene oxide (rGO) and pristine graphene (G), the oxygen functional groups were reduced. The effect of raising the C/O ratio of GO, rGO, and G blending with PE and PP synthesized by solution blending is discussed. Solvent processing was used to synthesise these nanocomposites, with dimethylformamide) DMF (and o-xylene served as the solvents for graphene flakes and polymers, respectively, before the two components were combined to form a well-mixed initial state. Wide-angle X-ray diffraction was used to investigate the crystallisation of the nanocomposites (WAXD). X-ray photoelectron spectroscopy (XPS), ultraviolet visible spectroscopy (UVVS), and Raman spectroscopy were used to characterise the chemical structures, with the latter being used to calculate the intensity ratio of D and G band (ID/IG) value for pure graphene specimens. The C/O ratio was calculated as , 4.9 and 2.2 for the G, rGO and GO respectively. While the (I_D/I_G (increased with increasing the C/O ratio, the I_D/I_G values were calculated as 0.285, 1.137 and 1.726 for pure GO, rGO and G samples. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to determine the melting temperature ( ), crystallization temperature ( ) as well as a range of degradation temperatures.

Abstract: We report on experimental and theoretical studies of the electronic structure of ternary Tl₄CdI₆ alloy. Our XPS results indicate low hygroscopicity of its surface. The first-principle calculations indicate that the valence-band region of Tl₄CdI₆ is dominated by contributions of I 5p states (mainly at the top and the central portion), while its bottom is prevailed by contributions of Tl 6s states. The theoretical data indicate that the Tl₄CdI₆ compound is a direct gap semiconductor with the band gap value of Eg = 2.03 eV. The calculations reveal that the significant covalent component (in addition to ionic component) is characteristic for the chemical Tl–I and Cd–I bonds of Tl₄CdI₆.

Abstract: This paper studied the alternative method for determination of percentage of grafted content in the grafted low density polyethylene (LDPE) film with black seed oil (BSO). BSO was grafted onto LDPE by pre-irradiation grafting method and the grafted samples were evaluated using FTIR qualitative and quantitative analysis. The grafting yield was calculated quantitatively from absorbance peak of two difference peak (1464cm^-1 and 1746cm^-1). Control LDPE film shows no absorbance peak at wavenumber of 1746cm^-1 while, a peak appears for grafted film at the same wavenumber. Therefore, it is possible to consider the peak area in this wavenumber as the grafting extension of BSO in LDPE film. Meanwhile, concerning the infrared (IR) fingerprint of LDPE film, consistent peak characteristic bands of LDPE are also present for all grafted sample at 1464cm^-1. Thus, the grafting yield is computed by using these peaks. Then, further confirmation grafting of BSO onto LDPE film was supported by the XPS spectroscopy. The atomic composition of C decreased 13% after LDPE film was grafted with BSO. While, the O content increases from values of 6.9% to 19.2% after grafting reaction. The increment percentage of O1s after grafting reaction mainly caused by the incorporation of oxygen content of a new polar functional groups of BSO on the surface of LDPE films. These results are in good agreement with FTIR analysis.

Abstract: Cerium oxide (CeO₂) is one of potential candidates of hydrophobic coatings servicing in harsh environments. In this letter, abraded CeO₂ surface was prepared using sandblasting treatment to investigate the wetting mechanism under the condition of impact abrasive wear. The water contact angle (WCA) of the abraded surface increased from 62.8° to 93.7° after aging in ambient air for about 700 h. The hydrophobic self-optimisation mechanism of the abraded CeO₂ surface is due to the hierarchical structure formed during impact abrasive wear and the surface adsorption of airborne hydrocarbon, resulting the wetting state changed from “Wenzel state” to “Cassie-Baxter State”.

Abstract: Group III–V compound semiconductors are attracting attention as new channel materials that have higher carrier mobility than Si. However, defects easily occur at the interface between the semiconductor and insulator film, which degrades performance. In an earlier study, we demonstrated that the interfacial properties of InP are degraded by the growth of In₂O₃ and that In₂O₃ grows better in water than in air. Therefore, it is necessary to suppress the growth of In₂O₃ to improve the interfacial properties of InP. In this work, we focused on functional water, which can be controlled by adjusting the water conditions, and investigated the growth behavior of In₂O₃ in functional water. As a result, we found that the growth is suppressed in the low-pH range and in hydrogen water. It is important that H⁺ ions reduce OH⁻ ions, which contributes to the reaction with InP.

Abstract: Scandium aluminum nitride (ScxAl1-xN) is a promising material for sensor applications as it exhibits enhanced piezoelectric properties compared to pristine AlN while maintaining other advantageous properties like high thermal stability. Magnetoelectric sensors in particular are used to detect magnetic fields which leads to special requirements regarding the investigated ScAlN in order to achieve high sensor sensitivities. Co-sputtered ScAlN layers are investigated in this work using XRD, XPS, FTIR and Raman spectroscopy for scandium concentrations from 0 to 34 %. The impact of Sc incorporation regarding residual biaxial strain and bond softening is discussed on basis of the experimental results. The activity of the B1 and E2 modes found in the FTIR measurements is of special interest as the presumably oxygen related excitation is expected to influence the piezoelectric properties.

Abstract: Herein, the spinel Co_1-xZn_xFe₂O₄ (x = 0.0, 0.2, 0.4 and 0.6) powder samples have been prepared by the solid-state reaction method. We have carried out the measurements of crystal structure, element analysis, material characterization, magnetic property and Curie temperature using the X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer, and the first-principles calculations within the framework of the density functional theory (DFT). The EDS measurement indicates that the Co_1-xZn_xFe₂O₄ powder samples have been successfully synthesized and exhibited the cubic spinel structures. Both the lattice constant and crystallite size increase with the Zn concentration due to the larger ionic radius of Zn²⁺ ion than the Co²⁺ ion. The concentration ratio of the Co²⁺ and Co³⁺ ions can be predicted by the distribution of cations between the A and B sites by the XPS measurement. For the magnetic properties, the residual magnetization, coercivity and Curie temperature decrease monotonically as the Zn concentration increases, while the saturation magnetization initially increases and then decreases at the room temperature. For the Co_0.8Zn_0.2Fe₂O₄ sample, the magnetic saturation reaches the maximum value of 62.98 Am²kg^-1, due to a large amount of the Co³⁺ ions. The adequate replacement of Zn ion for the Co site can improve the magnetic properties of spinel Co_1-xZn_xFe₂O₄ powders, and effectively regulates the Curie temperature.

Abstract: In this contribution we investigate the formation at high temperature of an oriented 3C-SiC seed on various orientations of Si substrates “pre-carbonized” through Plasma Immersion Ion Implantation (PIII) process.