Effect Of Doping Concentration Research Articles

The effect of Mg doping concentration and annealing on the structure and luminescence properties of ZnO thin films

The effect of Mg doping concentration and annealing on the structure and luminescence properties of ZnO thin films

Effect of different doping concentrations of X (X = O, Se, Te) on the electronic and optical properties of single layer WS2

In this paper, we study the effects of different doping concentrations of O, Se, and Te atoms on the electronic structure and optical properties of single layer WS2 based on the density generalization theory of the first principles. The most stable structure. The system doped with Te atoms shows a shift from direct to indirect band gap, and the band gap of the system doped with Se atoms increases slightly. When investigating the optical properties, we also found that the absorption of light in each doped system mostly occurs in the ultraviolet region, and the absorption of light in the system doped with O atoms decreases, while the absorption of light in the system doped with Se and Te atoms changes with different frequencies. The reflectivity is higher than the intrinsic state.

Effects of Ta concentration on microstructure, optical and optoelectronic properties of Ga2O3:Ta films

Ga2O3 material possesses extensive application potential and research value. Doping other elements into intrinsic Ga2O3 is one of the common methods to enhance its performance and is also a hot research direction nowadays. In this paper, Ta element was introduced into Ga2O3 material, and Ga2O3:Ta thin films with different Ta doping concentrations were fabricated using a dual-target RF co-sputtering system. The effects of Ta doping concentration on microstructure, optical, and optoelectronic properties of the films were meticulously investigated, and the optimal Ta doping concentration was determined. XPS results reveal that Ta entered Ga2O3 lattice with a +5 oxidation state, and combined with EDS results, it is inferred that Ta successfully partially substitutes Ga. XRD and XPS results indicate that when the sputtering power of Ta2O5 is 30 W, corresponding to a Ta doping concentration of 2.39 at.%, the film exhibits enhanced crystallinity. The Ga2O3-based MSM detector prepared under this condition demonstrates superior stability and detection sensitivity. Additionally, it also exhibits stable photoresponse to 365 nm light. This work promotes the application of Ga2O3 material and provides new insights into improving the stability and performance of ultraviolet photodetectors.

Preparation, characterization, and antibacterial activity of Ni, Sn co-doped ZnO nanoparticles: Effect of Sn doping concentration

Ni, Sn co-doped ZnO nanoparticles have been prepared by chemical method at room temperature. The effects of Sn on the structural, morphological, optical, electrical, and anti-microbial properties of the prepared nanoparticles have been evaluated and discussed. The crystallite size and the unit cell properties have been influenced by the doping concentration of Sn. The addition of Sn enhances the texture coefficient of the nanoparticles. The optical band gap of the material is blue-shifted as the doping concentration of Sn increases. The prepared nanoparticles have high hole concentration than electron concentration. The nanoparticles became more transparent at high doping concentrations. The effect of Sn concentration against E. coli, S. aureus, and P. aeruginosa has been evaluated.

A study of the effect of cerium ion doping concentration on the structural, electrical, and thermoelectric properties of CaMnO3 nanoparticles

Abstract Universally, energy loss in the form of heat is predominant and this heat is irrecoverable waste heat that leads to global warming. Clean, green, eco-friendly, cost-effective, and renewable energy sources are the possible solutions for this energy crisis and global warming issues. Thermoelectric power generation is a promising technology by converting this irrecoverable waste heat directly into electricity without any greenhouse gas emission. Nanostructured CaMnO3 at various cerium concentrations have been successfully prepared by sol–gel hydrothermal method followed by annealing and sintering. Pure and doped samples were systematically characterized by DSC, powder XRD, RAMAN, SEM with EDAX and FTIR spectroscopy. Electrical and thermoelectrical measurements were carried out on the sintered pellets. The XRD analyses confirmed the formation of orthorhombic perovskite structure for all the samples and the average particle size lies in the range of 50–60 nm. FTIR analysis shows the presence of CaMnO3 nanoparticles without any impurities. The temperature dependence of physical properties was performed and analyzed between room temperature and 600 °C. Electrical resistivity strongly depends on the nature of substituent ions and negative values indicate that the electrons are major charge carriers. Large Seebeck coefficient value and high-power factor make Ca1−x Ce x MnO3 an efficient thermoelectric material for energy storage applications.

Effects of Rare-Earth Elements Doping on Micro-Structure and Fluorescence Performances of Fluorapatite

For purposes of optimizing the microstructure and fluorescence properties of rare-earth elements (REEs)-doped fluorapatites (FAps), various kinds of REEs (La, Pr, Sm, Eu, Gd, Ho, Er, and Yb) with the concentration of 2~20 mol.% have been inserted into the FAps framework via hydrothermal method, in order to investigate the influential mechanism of the REEs on the crystal structure, morphology, and fluorescence under the excitation of the near-ultraviolet light of the FAps. Experimental results show that the wavelength of the emitted light of the REEs-doped FAps is decided by the type of REEs. Unlike the Pr/Yb- and Ho-doped FAps and with the fluorescence of red and green emitted light, respectively, the Er-doped FAps show a blue light emission with wavelengths of 296, 401, and 505 nm, which is, moreover, different with the Eu-doped Faps, showing an orange light emission with wavelengths of 490, 594, and 697 nm. The emission luminous color is related to the lattice defects of the FAps doped with the various types and the effective doping concentration of the REEs. The luminous intensity increases with the increase in the effective doping concentration of the REEs. Nevertheless, the formation of rare-earth fluoride results in the decrease in the effective doping concentration of the REEs and the luminous intensity. The FAps with an effective doping concentration of 7 mol.% Er and 3 mol.% Eu show relative excellent fluorescence properties.

Study of bulk damage of high dose gamma irradiated p-type silicon diodes with various resistivities

The bulk damage of p-type silicon detectors caused by high doses of gamma irradiation has been studied. The study was carried out on three types of n+-in-p silicon diodes with comparable geometries but different initial resistivities. This allowed to determine how different initial parameters of studied samples influence radiation-induced changes in the measured characteristics. The diodes were irradiated by a Cobalt-60 gamma source to total ionizing doses ranging from 0.50 up to 8.28 MGy, and annealed for 80 minutes at 60 °C. The Geant4 toolkit for simulation of the passage of particles through matter was used to simulate the deposited energy homogeneity, to verify the equal distribution of total deposited energies through all the layers of irradiated samples, and to calculate the secondary electron spectra in the irradiation box. The main goal of the study was to characterize the gamma-radiation induced displacement damage by measuring current-voltage characteristics (IV), and the evolution of the full depletion voltage (V FD) with the total ionizing dose, by measuring capacitance-voltage characteristics (CV). It has been observed that the bulk leakage current increases linearly with total ionizing dose, and the damage coefficient depends on the initial resistivity of the silicon diode. The effective doping concentration and therefore V FD significantly decreases with increasing total ionizing dose, before starting to increase again at a specific dose. We assume that this decrease is caused by the effect of acceptor removal. Another noteworthy observation of this study is that the IV and CV measurements of the gamma irradiated diodes do not reveal any annealing effect.

Effect of dopant concentration on femtosecond pulsed laser irradiation of yttria-stabilized zirconia for generating nanopores

Yttria-stabilized zirconia (YSZ) is a fine ceramics material that has been applied to dental implants and mechanical components. As YSZ is a hard, brittle, and chemically stable material, that undergoes phase transformation during mechanical loading, it is difficult to fabricate nanostructures using mechanical processing methods. In this study, a surface structuring method using a femtosecond pulsed laser was proposed, which is effective in suppressing the mechanical loading-induced phase transformation. As the material properties of YSZ vary with the concentration of yttria dopant, polycrystalline zirconia samples with different yttria concentrations (2, 3, 5, and 8 mol%) were used to investigate the effect of yttria concentrations on laser processing characteristics for nanostructuring. At all concentrations, nanopore generation in the surface grain was achieved by laser irradiation near the ablation threshold. In addition, there was no significant change in the crystal structure before and after laser irradiation, and no damage to the bulk occurred. At 2 mol%, intergranular cracks were generated around the pores. By increasing the dopant level to 5 mol%, the lens effect of the crystal grains became stronger due to enhanced grain growth, and the diameter and number of pores increased. In addition, pores formed preferentially on smaller grains at 5 mol%. However, for YSZ with 8 mol%, the pore formation phenomenon was different from that in the lower dopant level, as the area near the grain boundary was preferentially ablated, and microcracks formation and exfoliation of the surface also occurred. These results contribute to a deeper understanding of the laser ablation characteristics of zirconia with different dopant levels and to the development of surface structuring methods for fine ceramics materials.

High DC-Bias Stability and Reliability in BaTiO3-Based Multilayer Ceramic Capacitors: The Role of the Core-Shell Structure and the Electrode.

With the miniaturization of multilayer ceramic capacitors (MLCCs) and the increase of the electric field on a single dielectric layer, dielectric constant DC-bias stability and reliability have gradually aroused attention in the advanced electronics industry. In this study, MLCCs with outstanding DC-bias stability and reliability were prepared by using dielectric ceramic optimization and electrode optimization strategies. The effect of the Dy-Y doping concentration on the microstructure, dielectric properties, and reliability of BaTiO3-based ceramics was investigated. The shell ratio and effective shell doping concentration of the core-shell structure in ceramic grains play important roles in defects and electrical performances. The ceramic with appropriate doping contents shows a dielectric constant of 1800 and a dielectric constant change rate of -17% under a DC field of 4 kV/mm, which was fabricated into prototype MLCCs with different Ni electrodes. MLCCs exhibit outstanding DC-bias stability with a -28% degradation in the dielectric constant under a DC field of 4 kV/mm while possessing a dielectric constant of 2300 and satisfying the EIA X7S specification. Additionally, it was discovered that MLCCs prepared by using fine-size Ni particle electrodes have low electrode roughness and high interfacial Schottky barriers, resulting in better reliability. This study provides promising candidate materials and theoretical references for high-end and high DC-bias stability MLCCs.

Electrochemical lift-off of GaN films for GaN-on-GaN technology

Lifting off the native GaN substrate is an essential step in the fabrication of high-performance devices. In this study, we report a method to separate GaN thin films from GaN substrate through electrochemical (EC) lateral etching. By employing tetramethylammonium hydroxide to treat the dry-etched sidewalls, we addressed the issue of non-uniformity at the EC etching front. Meantime, we investigated the effect of Si doping concentration on the roughness of the lift-off GaN films. It is found that as increasing the doping concentration, the roughness decreases together with a reduced applied bias. Finally, we achieved an epitaxial-level smooth surface with a small roughness of only 0.3 nm.

Enhancement of electron transport mobility in GaAs/InGaAs asymmetrically doped narrow quantum well pHEMT structure

We study the effect of asymmetric doping concentrations on the electron mobility μ in GaAs/InGaAs-based single quantum well (SQW) as well as double quantum well (DQW) pseudomorphic high electron mobility transistor (pHEMT) structures. Unequal doping in the substrate and surface barriers (n d1 and n d2 ) causes asymmetric distributions of subband wave functions, ψ 0 and ψ 1, which influence the subband scattering rate matrix elements (SSRME), thereby affecting the subband mobility μ n . For narrow well widths (w w ), in SQW structures, mostly a single subband is occupied. We show that an increase in n d2 , keeping n d1 fixed, enhances μ nonlinearly. The interface roughness (ir-) scattering mostly dominates μ in thin wells (w w < 70 Å), while generally, μ is determined by ionized impurity (ii-) scattering and to some extent by alloy disorder (ad-) scattering. The influence of ir-scattering enhances, while ad-scattering diminishes, by reducing n d2 . For DQW, a double subband is occupied. In a symmetric DQW structure at resonance, n d1 = n d2 , ψ 0 and ψ 1 equally extend into both the wells. For a minor variation, say n d1 > n d2 , ψ 0 mostly lies in one well while ψ 1 is in the other well. In the case of n d1 < n d2 , the distribution reverts. The substantial changes in ψ 0 and ψ 1 influence the intra- and inter-SSRME differently through intersubband effects, leading to nonlinear μ n as a function of n d2 . Taking n d1 + n d2 = 3 × 1018 cm−3, we show that for w w1 = w w2 = 80 Å, a shallow dip in μ occurs at n d1 = n d2 = 1.5 × 1018 cm−3. Whereas, for w w1 = 60 Å and w w2 = 100 Å, the dip in μ occurs near the corresponding resonance, n d1 = 2.3 × 1018 cm−3 and n d2 = 0.7 × 1018 cm−3. Our results of nonlinear μ can be utilized for performance analysis of pHEMT.

Direct growth of few-layered graphene on boron doped diamond surface with varying boron doping concentration

The diamond-graphene heterostructure is a promising all‑carbon composite structure, which can take advantages of excellent properties of these two materials. At present, the diamond-graphene heterojunction were mostly synthesized by chemical vapor deposition (CVD) method with intrinsic diamond substrate. In this study, the few-layered graphene is synthesized on boron-doped-diamond (BDD) surface through a simple thermal treatment method with Ni catalyst. The effects of boron doping concentration of substrate on the synthesis of diamond-graphene heterojunctions is studied. It demonstrates that the surface morphology and roughness are improved with the increasing of substrate doping concentration. Compared with the light doped and un-doped diamond, the number of graphene layers and quality decreases and increases, respectively.

Effect of Cobalt Doping on The Structural, Linear and Nonlinear Optical Parameters of Manganese Oxide Thin Layers

AbstractIn this study, undoped and cobalt‐doped manganese oxide Co:Mn3O4 (0, 2, and 4 at%) are elaborated by the spray pyrolysis procedure on glass substrates. The effect of cobalt doping concentrations on the structural, morphological, and optical features (linear and nonlinear) are investigated through the X‐ray diffractometer, Raman spectroscopy, Scanning Electron Microscopy with an attached energy dispersive X‐ray and UV–Vis‐NIR spectrophotometer. The XRD investigations exhibit a polycrystalline tetragonal structure for all Co:Mn3O4 and confirm by Raman results with the distinctive tetragonal mode A1g at 657 cm−1. The SEM images show an increase in roughness as cobalt doping concentration increases. The EDS quantitative analysis revealed the presence of manganese, oxygen, and cobalt. Furthermore, the optical investigation is pursued firstly through the linear optical that showed a decrease in the transmittance, and optical band gap energy as the cobalt concentration increased due to oxygen vacancies and defects and the increase of refractive index from 2.05 to 2.21. Second, the nonlinear optical parameters show a high value of the nonlinear refractive index 3.75 × 10−7 (esu) and the third‐order susceptibility χ3 = 2.2 × 10−8(esu) of Co:Mn3O4(2at%). These values put the Co:Mn3O4(2at%) thin layer as a candidate in the optoelectronic applications as a third‐order nonlinear medium.

Tailoring the structural, magnetic and dielectric properties of cobalt ferrites by chromium substitution

Ferrites are renowned for their extensive use in a variety of industries, from manufacturing to the biomedical field. In the current study chromium substituted cobalt ferrite nanoparticles (CoCrxFe2-xO4,x = 0, 0.25, 0.5, 0.75, and 1) were synthesized by utilizing the sol–gel auto combustion method. Various analytical tests confirm the effect of Cr doping concentration on cobalt ferrites. The structural and morphological analysis of samples were done using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) respectively. The samples' pure spinel structure was confirmed by XRD analysis. Magnetic characterization at room temperature and low temperature were carried out using Quantum Design's PPMS. The dielectric properties of the samples were examined using a Hioki 3532 LCR hitester. The results demonstrate the effect of chromium substitution in cobalt ferrites and suggest the possible uses of the prepared samples.

Effect of nitrogen and transition-metal co-doping on quantum capacitance enhancement of graphene as supercapacitor electrodes: A density functional theory study

Quantum capacitance plays a crucial role in determining the energy density of graphene-based supercapacitors. In this study, density functional theory calculations were conducted to investigate the enhancement of quantum capacitance and surface storage charge density through the co-doping of transition metals (TM) such as Mn, Fe, Co, Ni, Cu, Zn, Cr, V, Ti, and N atoms in graphene (TMN3-G). At a doping concentration of 2 at% (atomic percentage), all types of metal doped graphene exhibited an increase in quantum capacitance compared to pristine graphene. The highest increase was observed in CrN3-G, where the maximum quantum capacitance increased from 19.2 μF/cm2 for pristine graphene to 122.8 μF/cm2, due to the increased density of states around the Fermi level. The maximum surface storage charge density also increased from 6.4 μC/cm2 for pristine graphene to 44.4 μC/cm2 for CrN3-G. Moreover, the study investigated the effect of different doping concentrations on quantum capacitance performance by changing the doping concentration for VN3-G. It was found that the quantum capacitance for VN3-G increased with higher doping concentration, reaching up to 282 μF/cm2 when the doping concentration was increased to 12.5 at% from 2 at%. Based on our calculation results, ZnN3-G, NiN3-G, CrN3-G, and TiN3-G are suitable for the anode of supercapacitors, while CuN3-G and CoN3-G are suitable for the cathode. FeN3-G, MnN3-G, and VN3-G are suitable for both electrodes. These findings provide valuable insights for designing high-capacity graphene-based supercapacitors.

Crystallization and optical properties of Eu2+: CsCaCl3 nanocrystals in glasses

Narrow-band blue luminescence materials are desirable in full color display with wide color gamut. Divalent rare earth europium doped luminescence materials show excellent optical properties as promising backlit materials in display. However, narrow-band blue luminescence materials are still lacking. Herein, novel blue emitting Eu2+: CsCaCl3 NCs are precipitated in the glasses, and effects of EuCl3 doping concentration and heat-treatment conditions on the growth behavior and optical properties of Eu2+: CsCaCl3 NCs precipitated in glasses are investigated. Doping concentration of EuCl3 in glass and the heat-treatment condition can effectively regulate the Eu2+/Eu3+ molar ratio in glasses, size of Eu2+: CsCaCl3 NCs, and effective doping concentration of Eu2+ ions in CsCaCl3 NCs formed in the glasses. Besides, effect of phase separation on glass transmittance is explored to improve the glass optical properties. Upon incorporation of Eu2+ ions into CsCaCl3 NCs in glasses, blue photoluminescence at 435 nm with full width at half maximum of 22 nm and color purity of ∼97.2 % is realized, and concomitantly, photoluminescence lifetimes are extended and quantum efficiency are significantly improved. These results demonstrate that Eu2+: CsCaCl3 NCs doped glasses are promising blue emitting materials.

Computational study of thermophysical properties of cerium doped UO2: Effect of oxidation states

The interaction of fission products with UO2 fuel, which is generated during the nuclear fission, can amend the fuel behavior. Among different lanthanide (Ln) fission products produced, Cerium (Ce) shows considerable yield. The Ce substitution in UO2 with isovalent Ce4+ cation is interesting due to the absence of oxygen vacancies and no change in the oxidation state of U atoms in the doped system. In this study, the trivalent and tetravalent Ce atom substitution in UO2 and their effect on thermophysical properties is investigated using density functional theory. Further, the effect of Ce doping concentrations in UO2 is assessed by varying the Ce ion concentrations in the lattice (6.25 %, 12.5 %, 25 %, and 50 %) for various charge balancing mechanisms. The lattice volume of Ce doped UO2 structures show higher or lower values compared to undoped UO2 depending upon the oxidation state of Ce and U atoms. The bulk modulus tends to reduce for Ce substituted UO2 as compared to pure UO2. The electronic density of states analysis shows that Ce substitution levels as well as the oxidation state of Ce/U atoms strongly influences the band structure of the UO2 lattice. The specific heat capacity of Ce doped UO2 structures is calculated at different Ce doping concentrations and for disparate charge balancing procedures using the quasi harmonic approximation(QHA). Present results show good agreement with the experimental values reported for similar Ce substituted UO2 structures. Thus, the systematic investigation with varying Ce fission product concentrations and oxidation states of cations (Ce and U) can give insight into the fuel properties of UO2 under reactor conditions.

Enhanced dielectric properties of zinc doped bentonite composites: an effect of cobalt doping concentrations and tight binding calculation

In this study we have successfully synthesized undoped and Zn and Co incorporated bentonite samples. The amount of Zn was kept constant while as Co amount was varied. All the synthesized samples were characterized using x-ray diffraction analysis which confirms the predominant presence of montmorillonite in all the samples thus confirming successful formation of bentonite. Similarly, EDX analysis confirms successful incorporation of Zn and Co in Ben sample. The analysis of the dielectric properties of the produced samples was successfully carried out, and the frequency dependence of the dielectric constant and dielectric loss was explored. According to the results, all the samples exhibit considerable dielectric dispersion at lower frequencies, whereas steady dielectric constant and modest dielectric loss are shown at higher frequencies. The effect of Zn, Co incorporation and temperature dependence of dielectric behaviour of all the samples was also analysed and it was observed that at low temperatures undoped Ben samples showed high dielectric constant while as at higher temperatures the incorporation of Zn and Co enhances the dielectric constant of as prepared sample. Similarly, the variation of conductivity of as prepared samples with frequency and temperature was analysed and it was observed that all the samples show similar conduction behaviour and follows correlated barrier hopping type of conduction. The real and imaginary part of electric modulus as a function of frequency was also analysed. Further, theoretical analysis showed considerable change in HUMO and LUMO which is considered as a main reason responsible for change in dielectric characteristics of Ben and Zn/Co incorporated samples. From this study it was observed that the incorporation of metal ions into the layered bentonite improved the dielectric properties at high temperature thus this study provides a new insight into the development of new dielectric materials which could be used under high temperature operation conditions.

Investigation on the microstructural, optical, electrical, and photocatalytic properties of WO3 nanoparticles: an effect of Ce doping concentrations

Investigation on the microstructural, optical, electrical, and photocatalytic properties of WO3 nanoparticles: an effect of Ce doping concentrations

Device modeling of all-inorganic CsPbI3 based perovskite solar cells: A numerical study

Lead-halide based perovskite solar cells (PSC’s) have proven to be efficient and have extraordinary stability. CsPbI3 is thought to be a potential light-absorbing material for use in all-inorganic PSCs due to its advantageous bandgap and thermal stability. In contrast to the organic-inorganic hybrid PSCs counterpart, the CsPbI3 has a high defect density resulting in a lower PCE and less stable structure. In this study, we performed a device modeling of all-inorganic CsPbI3 using SCAPS-1D to improve its performance. Here, we have shown how various electron and hole transport layers (ETL & HTL) affect the performance of the CsPbI3 device. For this, the effect of dopant concentration, the thickness of HTL, ETL, and absorber layer along with optimization of back contact metal work function have been numerically investigated. Under the optimum condition, the best theoretical conversion efficiency of ∼27.04% was achieved for FTO/SnO2/CsPbI3/CuSbS2/Pd configuration, which is the highest theoretical value reported among CsPbI3-based PSCs. Based on these results, we concluded that all-inorganic CsPbI3 PSCs under these optimized conditions might help researchers improve this material experimentally for renewable energy applications.