Papers by Keyword: Doping

Abstract: Lithium-rich layered oxide cathode materials have the advantages of a high voltage and a high specific capacity. Their commercial applications have however been impeded by some disadvantages such as low initial coulombic efficiency and low cycle life. To overcome these issues, rare earth ion-doped lithium-rich layered oxide cathode materials are investigated in this work. The irreversible release of O^2- in Li₂MnO₃ is suppressed by rare earth ions doping, which enhanced the initial coulombic efficiency of the materials. Meanwhile, the rare-earth ion radius used for doping is larger than the Mn⁴⁺ radius, which enlarges the (003)-crystalline plane spacing, resulting in a significant enhancement of the rate performance of the material.

Abstract: The nanosized samarium doped tin oxide in varying concentration (0%, 0.5%, 1%, 3%, 5%) was successfully synthesized using the wet chemical precipitation approach. X-ray Diffraction (XRD) analysis was done to monitor the effect of the dopant concentration to the host lattice as broadening and narrowing of the formed peaks are seen. Average crystallite sizes of the produced sample are ranging from 9-28 nm, confirming it to be nanoscale. Identified peaks with Miller indices of ((110), (101), (200), (111), (211), (220), and (002) signifies a tetragonal rutile structure of the synthesized samples. Scanning Electron Microscopy (SEM) shows the difference in morphology for the powdered samples as per different samarium loading as well as the shape, which is granular. Energy Dispersive X-ray spectroscopy (EDX) affirms the successful integration of the samarium dopant to the lattice structure of the SnO₂.

Abstract: The memory effect of Al doping in 3C-SiC prevents sharp interfaces between layers of different doping levels and can lead to unintentional doping of subsequent epilayers and even growth runs. Introducing HCl into the growth phase of 3C-SiC reduces the Al incorporation but has a significant impact on Al dopant decay rates and background levels within the chamber, resulting in far sharper doping profiles. The impact of relatively high flow rates of HCl is low within a chlorine-based growth system giving fine control over its influence on the growth process and memory effect.

Abstract: We discuss two defect related practical improvements in the corona noncontact CV metrology, (CnCV) for SiC. The improvements are introduced in response to requests from industrial tool users. The first improvement quantifies mapping of electrically active defects with the QUAD technique (Quality, Uniformity, and Defects). It provides the capability of user selectable die grids directly comparable with Near UV-PL and optical defect mapping. This shall enhance understanding of the device killer defects and help to correlate epilayer defects and device yield. The second improvement introduces auto-remeasurement of outliers appearing in doping measurements on defective sites. This procedure is analogous to that used in the Hg probe technique and it provides a means for correcting defect related distortions in SPC doping monitoring charts.

Abstract: In this work, TiO₂ was applied to cotton fabric by a sol–gel-hydrothermal process. A combination of 3-(trihydroxysilyl) propyl methylphosphonate monosodium salt solution (TPMP) and (3-aminopropyl)triethoxysilane (APTES) was used as a matrix to enhance the interfacial interaction between TiO₂ and surface of the cotton fibres. During the hydrothermal treatment, silver nitrate (AgNO₃) or reduced graphene oxide (rGO) were added to produce Ag-doped TiO₂- or rGO-coupled TiO₂-coated textiles. The successful application of all investigated components on cotton fabric was confirmed by the analysis of SEM and EDS. The results of UPF determination and self-cleaning activity showed excellent performance of both studied nanocomposite coatings, whereas the use of rGO proved to be better than Ag.

Abstract: Silicon on insulator (SOI) wafer has allowed the integrated circuit (IC) industry to create superior, high-performance solutions. In addition, doping techniques are vital in the silicon sector due to the need to regulate the material electrical properties. The spin on dopant (SOD) approach is an alternative method that involves spinning a solution containing dopant onto SOI wafers. This research aims to determine the impact of thermal diffusion temperature and soaking time on sheet resistance of doped SOI wafer using SOD approach. Additionally, the homogeneity of doping was studied by utilizing mapping techniques. Three inches boron-doped SOI wafers were cut and cleaned according to Radio Corporation of America (RCA) standards. N-type dopants of Filmtronics SOD P509 were deposited on SOI wafer by using a spin coater, for 40 seconds at 4,000 revolutions per minute (rpm). The thermal diffusion temperature and soaking time were set between 700°C to 1000°C for 30 to 120 minutes. After thermal diffusion, hydrofluoric acids (HF) were diluted and used to etch samples. All materials were evaluated using a four-point probe, Hall Effect and Atomic Force Microscope (AFM). The results show that when the thermal diffusion soaking time increases, sheet resistance decreases until activated dopants are saturated. When sheet resistance decreases, dopant concentration rises. Temperature and soaking time increase carrier density and surface roughness, while decreasing Hall mobility. From mapping techniques, it shows low non-uniformity value which less than 10% suggests good thermal diffusion control.

Abstract: In this work, the optical and structural properties of the modified crystalline structures of the nanostructured cadmium sulphide (CdS) semiconductor caused by doping with (Cu²⁺, Ag⁺, Au⁺) transition metal ions are studied. Using the chemical bath deposition technique, thin CdS films of good crystalline quality were deposited, which were doped in synthesis without the need for additional steps, obtaining thicknesses of around 100 nm. The chemical binding energies and their interactions of the CdS semiconductor compound with the different transition metal ions were determined by X-ray photoelectron spectroscopy. The crystalline and quality phase of the CBD-CdS thin films were determined by X-ray diffraction that were confirmed by Raman scattering, obtaining that the dominant crystalline phase is zinc blende in the (1 1 1) crystalline direction. A change in crystalline quality from monocrystalline to polycrystalline was observed by XRD in the CdS thin films doped with transition metal ions, keeping the crystalline direction (1 1 1) of the zinc blende phase of CdS as the dominant one; this crystalline behaviour was confirmed by HRTEM micrographs, in addition to the different levels of quantum confinement favoured by each transition metal incorporated into the CdS. By Raman scattering measurements, the crystalline zinc blende phase of CdS was confirmed and also allowed the analysis of the phononic interactions of the binary compound, where Raman shifts provided information on the structural quality and also confirm the effects of quantum confinement. UV-visible optical spectroscopy describes the effects of the crystalline structural modifications with blue shifts on the optical band gap energies of the evaluated CdS samples, related with the different levels of quantum confinement given by the (Cu²⁺, Ag⁺, Au⁺) transition metal dopants.

Abstract: Doping of perovskite solar cells is a regularly used approach to adjust and modify the structures and properties of organic-inorganic hybrid perovskite such as CH3NH3PbI3 material, and subsequently increase the conversion efficiency. In this work, optical absorption is calculated for copper-doped-perovskite material based on the density functional theory analysis for tetragonal crystal structures. We investigated the effect of doping CH3NH3PbI3 with copper, as an optical alternative to Pb atom in central tetragonal structure. As a conclusion, some enhancements of the optical properties by the replacement of Cu by the Pb atom are observed, such as optical absorption at certain visible spectrum regions, along with more intensive field mapping. This optical enhancement can lead to a better improvement of perovskite solar cell according to metallic-doing substitutional defect concept.

Abstract: This research uses the Solid State method to produce LiNi_xFe_1-xPO₄ /C Composite Materials with variation Ni ion doping are x= 0.01, 0.02, and 0.03, Characterization was carried out using XRD, PSA, SEM and EIS. The results of XRD analysis showed that LiFePO₄, Li₃Fe₂PO₄ and Fe₂O₃ phases were formed. The conductivity test results show that the conductivity of the LFP/C precursor is 10.24x10^-4 S/cm, the LiNi_0.01Fe_0.99PO₄/C precursor is 7.75 x10^-4 S/cm, the LiNi_0.02Fe_0.98PO₄/C precursor is 10.334 x10^-4 S/cm, and the precursor LiNi_0.03Fe_0.97PO₄/C was 4.87 x10^-4 S/cm . With the highest conductivity value at LiNi_0.02Fe_0.98PO₄/C precursor.

Abstract: The recently introduced corona charge non-contact capacitance-voltage technique, CnCV, is analyzed considering the production needs of epitaxial SiC wafers. The interfering mechanism of charge dissipation on fresh epitaxial 4H-SiC is identified as surface diffusion and is effectively eliminated by optimized ultraviolet pretreatment (UVPT). It is shown that optimized UVPT increases the CnCV dopant measurement voltage range and the depth of profiling. Concurrent UVPT and measurement provides a practical solution for improving throughput for multiple wafers. Electrical defect mapping shows that UVPT reduces the effective defect size. This will be helpful to avoid defects in patterns used for CnCV dopant measurements.