Effect Of Doping Concentration Research Articles

Electrical characterization of 180 nm ATLASPix2 HV-CMOS monolithic prototypes for the High-Luminosity LHC

We report on the experimental study made on a successive prototype of High-Voltage Complementary Metal-Oxide-Semiconductor ATLASPix2 sensor for the tracking detector application, developed with 180 nm feature size. These sensors are to qualify mainly the peripheral data processing blocks (e.g. Command Decoder, Trigger Buffer, etc.). Over a decade, the monolithic pixelated sensors for a foreseen application to the ATLAS High-Luminosity LHC upgrade are being investigated as a viable option and a significant R&D progress made. It is a smaller version of 24× 36 pixelated sensor in comparison to the earlier generation of ATLASPix1 fabricated in both ams AG, Austria, and TSI Semiconductors, U.S.A. . While ams produced ATLASPix2 showed breakdown voltage ∼50 V in nonirradiated condition as it was seen on its predecessors ATLASpix1, TSI produced prototypes reported breakdown voltage greater than 100 V . The chosen wafer of MCz 20 Ω ⋅ cm P-type substrate resistivity can deplete a few tenths of μ m, where the process-driven surface damage can have a greater impact on device operating conditions before and after irradiation. In an aim to understand device intrinsic performance at the irradiated case, a dedicated neutron irradiation campaign has been made at Jožef Stefan Institute in Slovenia for different fluences. Characterizations have been performed at different temperatures after irradiation to analyze the leakage current and breakdown voltage before and after irradiation. TSI prototypes showed a breakdown voltage decrease (∼90 V) due to impact ionization and enhanced effective doping concentration. Results demonstrated for the neutron-irradiated devices up to the fluence of 2× 1015 neq/cm2 can still safely be operated at a voltage high enough to allow for high efficiency. Accelerated annealing steps were also made on selective irradiated ATLASPix2 samples, equivalent to more than two years of room-temperature annealing (at 20 °C), and they showed the reassuring expected breakdown voltage increase and damage constant rate α* (geometry dependent) decrease, driven by the beneficial annealing.

Nonresonant Polarized Raman Spectra Calculations of Nitrogen-Doped Single-Walled Carbon Nanotubes: Diameter, Chirality, and Doping Concentration Effects.

Raman spectra of nitrogen-doped single-walled carbon nanotubes are calculated using the spectral moment's method combined with the bond polarizability model. The influence of the nanotube diameter and chirality is investigated. We also address the important question of the effect of the N-doping concentration, and we propose an equation to estimate the doping concentration from the knowledge of the tube diameter and the frequency of the radial breathing mode.

Hydration of acceptor-doped BaSnO3: Implications of the bound states of ionic defects

The implications of acceptor-bound ionic defects in the hydration of acceptor-doped cubic perovskite BaSnO3 are elucidated based on the thermogravimetric analysis of water uptake and the authors’ recent statistical theory. The oxides BaSn1–xScxO3–δ (0.10 ≤ x ≤ 0.37) and BaSn0.9Sc0.1–xInxO3–δ (x = 0.05, 0.10) were synthesized and experimentally studied. The thermogravimetric measurements showed very good hydration properties of BaSn1–xScxO3–δ: the low-temperature hydrogen concentration was close to the nominal dopant content for all doping levels. The obtained data pertaining to the dopant concentration effect on the hydration isobars are well described by the exploited theory that accounts for the trapping of protons and oxygen vacancies by acceptors. The experimental findings on the effect of scandium substitution with indium on the hydrogen dissolution in the BaSn0.9Sc0.1–xInxO3–δ oxides are also in good agreement with our theoretical predictions. In addition, we discuss the impact of trapping on the hydration enthalpy, entropy and Gibbs free energy of BaSnO3 doped with various acceptors, and establish the type and concentration of acceptor impurities which enhance or inhibit hydration. Our results testify to the pivotal role of the defects’ trapping by acceptors in the hydration of barium stannate, and demonstrate that this effect is important for understanding and prediction of the hydration properties of acceptor-doped perovskites.

Fabrication of tunable anatase/rutile heterojunction N/TiO2 nanophotocatalyst for enhanced visible light degradation activity

With special focus of the effect of dopant concentration on physicochemical properties, a series of visible light active nitrogen doped titania (N/TiO2) nanomaterials were successfully synthesized via sol-gel method of titanium butoxide in the presence of benign N dopant guanidium chloride. The resulting anatase/rutile (A/R) mixed phase materials were subjected to different characterization techniques, and their photocatalytic performance was evaluated against methylene blue (MB) dye under visible light irradiation. The results confirmed that the N was effectively doped in interstitial sites (7.2 atomic%) with Ti-N-O linkage, and the N/Ti mol ratio significantly dictated the physicochemical properties, and photodegradation of the photocatalysts. Notably, the mesoporous N/TiO2 (1:1 N/Ti, 42% A, 58% R with 2.91 eV band gap energy) demonstrated 97% photodegradation activity along with a fastest photodegradation rate of 0.033 min−1, which was 17 times faster than the undoped TiO2. Such excellent improvement was attributed to the synergistic effect of N-doping and optimal A/R phase composition that led to higher light absorption capacity and specific surface area, lower band gap energy and recombination rate as well as higher interstitial N in the crystal. Such promising green heterojunction photocatalysts have a broad range of applications from photocatalysis to photovoltaics.

Ag‐doped PbS thin films by nebulizer spray pyrolysis for solar cells

Silver (Ag)-doped PbS (PbS:Ag) thin films of 616 to 745 nm in thickness were prepared on glass substrates via cost-effective nebulizer spray method by adding different Ag levels from 2% to 8% at 200°C. For solar cell applications, the effect of Ag doping concentration on structural, morphological, optical, photoluminescence, and electrical chattels of PbS thin film has been studied. X-ray diffraction pattern confirmed the polycrystalline behavior of the prepared PbS:Ag films with cubic crystalline nature. The crystalline size and texture coefficient were increased by increasing Ag doping concentration. From the morphological studies by scanning electron microscope (SEM) and atomic force microscope (AFM), the grain size of the films and surface roughness values were increased for the increase in Ag doping concentration. EDS spectra confirmed the existence of Ag, Pb, and S elements in the select 6% Ag-doped PbS film. Peaks related to silver oxide started to emerge at 6% of Ag doping level. The optical direct band gap value was reduced from 1.51 to 1.17 eV for Ag doping from 2% to 6% and thereby slightly increased as 1.79 eV for 8% Ag doping level. For all PbS:Ag films, the photoluminescence spectrum emitted a strong near band edge (NBE) emission at approximately 580 nm, meaning better optical quality. Hall effect measurements evidenced that Ag doping provides enhancement on the characteristics of mobility, carrier concentration, and resistivity with p-type conducting nature. The observed high carrier concentration and low resistivity values were 4.32 × 1014 cm−3 and 80 Ωcm, for 6% Ag-doped PbS film. The FTO/CdS/PbS:Ag heterostructure solar cell was formed from 6% Ag-doped film.

Effects of Mg and Si doping in the guide layers of AlGaN-based ultraviolet-B band lasers

We investigated the effects of Si and Mg doping concentrations in the guide layers on the threshold power density of an AlGaN-based optically pumped ultraviolet-B band (UV-B) laser. For Si, a decrease in the threshold power density required for laser oscillation was confirmed at doping concentrations up to an order of 1017 cm−3. However, an increase was confirmed at high concentrations of approximately 1018 cm−3. For Mg doping, no decrease in the threshold power density of the optically pumped laser was confirmed even at low Mg concentrations, and it increased rapidly at 1018 cm−3. These results were characterized by weakly excited photoluminescence and variable stripe length, indicating that they were due to changes in optical gain with increasing or decreasing internal quantum efficiency and changes in internal loss. This suggests that Mg doping of the guide layer in UV-B lasers should be lower than 1018 cm−3 to realize low-threshold power density lasers. On the other hand, doping on an order of up to 1017 cm−3 for Si was effective at reducing the threshold power density. This indicates that the threshold power density increases if it is too high. These results could provide guidance for designing UV-B lasers in the future.

The rate of Cu doped TiO2 interlayer effects on the electrical characteristics of Al/Cu:TiO2/n-Si (MOS) capacitors depend on frequency and voltage

In order to determine the surface states (Nss), series resistance (Rs), and (Cu:TiO2) interlayer effects on the electrical characteristics of the Al/Cu:TiO2/n-Si metal oxide semiconductor (MOS) capacitors, both capacitance (C) and conductance (G) values were measured for frequency ranges of 10 kHz–1 MHz and ±5 V voltage ranges. In addition, to know Cu doping concentration effect on the MOS capacitor, the Al/Cu:TiO2/n-Si was fabricated with various rates Cu:TiO2 interlayer (5, 10, 15%) grown on n-Si susbtrate by spin-coating. The increase in capacitance via decreasing frequencies was attributed to the existence of Nss and their relaxation time. The frequency dependent diffusion potential (Vd), doping of donor atoms (Nd), Fermi energy (EF), barrier height (Фb) and depletion layer width (Wd) values were extracted from the linear part of reverse bias C−2-V curves. While the value the Rs decreased with increasing frequency, the Nss values increased for the three MOS capacitors. The profiles of Nss and Rs depending on voltage were also plotted by Nicollian-Brews methods and using high-low frequency (CHF-CLF) capacitance, respectively. The mean values of Nss for three capacitors were found at about 1012 eV−1cm−2 as suitable electronic devices. The lower values of the Nss can be attributed to passivation effect of Cu:TiO2 interlayer.

Photodegradation of 4-nitrophenol over B-doped TiO2 nanostructure: effect of dopant concentration, kinetics, and mechanism.

The 4-nitrophenol (4-NP) is one of the carcinogenic pollutants listed by US EPA and has been detected in industrial wastewater. This study investigates the photocatalytic degradation of 4-NP with TiO2 and boron (B)-doped TiO2 nanostructures. The degradation on undoped and B-doped TiO2 with various boron loadings (1-7%) was studied to establish a relationship between structure, interface, and photo-catalytic properties. The results of XRD, micro Raman, FTIR, and HRTEM show that the B doping has improved the crystallinity and induces rutile phase along with anatase (major phase). The N2 adsorption-desorption, SEM-EDX, and XPS indicated that the B induced the formation of mesoporous nanostructures in TiO2 and occupies interstitial sites by forming Ti-O-B type linkage. The surface area of pure TiO2 was decreased from 235.4 to 63.3m2/g in B-TiO2. The photo-physical properties were characterized by UV-Vis DRS, which showed decrease in the optical band-gap of pure TiO2 (2.98eV) to B-TiO2 (2.95eV). The degradation results demonstrated that the B doping improved the photocatalytic activity of TiO2; however, this improvement depends on the B concentration in doped TiO2. B-doped TiO2 (> 5% B) showed 90 % degradation of 4-NP, whereas the undoped TiO2 can degrade only 79 % of 4-NP. The degradation followed pseudo-first-order kinetics with rate constant values of 0.006min-1 and 0.0322min-1 for pure TiO2 and B-TiO2 respectively. The existence of a reduced form of Ti3+ on the surface of TiO2 (as evidence from XPS) was found responsible for enhancement in photocatalytic activity.

Si Wafer Dopant Concentration Effect on Light Emission of Solid State Incandescent Light Emitting Devices

Electrical and light emitting characteristics of solid state incandescent light emission devices made on p-type silicon wafers of various dopant concentrations have been studied. The number of conductive paths, i.e., nano-resistors, formed from the dielectric breakdown increased with the increase of the dopant concentration in the wafer, which is accompanied with the increase of the intensity of the emitted light. The breakdown voltage decreased with the increase of the dopant concentration. There exists a transition dopant concentration where the light intensity and the leakage current increase drastically with the increase of the dopant concentration. In summary, the dopant concentration in the silicon wafer is critical to the light emitting phenomenon of the solid state incandescent light emitting device.

Morphology and doping concentration effect on the luminescence properties of SnO2:Eu3+ nanoparticles

Morphology and Eu3+ doping effect on structural and photoluminescence properties of tin dioxide nanoparticles obtained by co-precipitation and hydrothermal methods are reported and analyzed for the first time. The samples were characterized by means of transmission electron microscopy (TEM), powder X-ray diffraction (XRD), specific surface area (SSA) estimation. TEM, XRD and SSA analyses showed that in the case of co-precipitation method the nanoparticles were spherical. Hydrothermal treatment leads to formation of cubic nanoparticles. An average particle size increased from 3 to 5 nm and from 6 to 11 nm along with increase of Eu3+ concentration for spherical and cubic nanoparticles, respectively. Steady-state and kinetics photoluminescence properties of nanophophors with different morphology were studied and compared. Radiative and nonradiative decay rates and Judd-Ofelt parameters were calculated using the model of 4f–4f intensity theory. It was shown, that preferred positions of substitution in SnO2 host differ depending on Eu3+ doping concentration and particle morphology.

Impact of Anionic Dopant Precursor on Nanostructured ZnO thin Films Surface Morphologies

The aim of this study is to investigate the impact of an anionic precursor [N2 gas and triethyleneamine (TEA) as nitrogen dopant source] to prepare anionic doped ZnO thin films surface morphologies, via a novel route - hydrothermal solution deposition at low temperature. The effect of dopant concentration under both with and without pH control was studied. The less populated doped ZnO crystal nearly had the same band gap as compared to undoped ZnO thin films. The photocatalytic activity of selected doped ZnO thin films were studied for the degrdation of 10 mg L-1 Methylene Blue under UV irradiation of 254nm. Based on the 1st order reaction rate constant results the morphology N2:S2-MS has shown highest degradation followed by N:S1-MS. Overall, the photocatalytic activity order is N2:S2-MS andgt; N:S1-MS andgt; N:S2-CG andgt; N:S1-CG. In general, a significant variation in surface morphologies, crystal size and population, porosity and orientation were observed. This tailored-made variation enabled the doped ZnO thin films to successfully degrade the waste methylene blue effluents.

Preparation and Characterizations Graft Copolymer of Poly(acrylamide-aniline)-Grafted Gum Ghatti

Abstract Hydrogels consist an assembly of cross-linked polymer networks with the ability to swell and hold huge volumes of water without dissolving. This behavior will depend on the cross-linked structure and the presence of hydrophilic groups in the polymeric chains. In this article, the conducting superabsorbent hydrogels were obtained by a two-step aqueous polymerization via free radical polymerization. In the first step, the grafting of acrylamide on gum ghatti was initiated by ammonium persulphate (APS) and crosslinking it with N, N'-methylene-bis-acrylamide (MBA) under vacuum by optimizing various reaction parameters. In the final step, grafting of aniline monomers on optimized graft copolymer ie. Gg-poly(AAm) was initiated again by APS and crosslinking it with MBA under vacuum. The effect of dopant concentration on the current-voltage characteristics of the conducting interpenetrating network hydrogel was studied. The grafting was confirmed by using XRD, FTIR, SEM and thermogravimetric analysis techniques. An endeavors have been made to relate the outcomes with available data to make the present work more useful from a scientific perspective

Impact of Anionic Dopant Precursor on Nanostructured ZnO thin Films Surface Morphologies

The aim of this study is to investigate the impact of an anionic precursor [N2 gas and triethyleneamine (TEA) as nitrogen dopant source] to prepare anionic doped ZnO thin films surface morphologies, via a novel route - hydrothermal solution deposition at low temperature. The effect of dopant concentration under both with and without pH control was studied. The less populated doped ZnO crystal nearly had the same band gap as compared to undoped ZnO thin films. The photocatalytic activity of selected doped ZnO thin films were studied for the degrdation of 10 mg L-1 Methylene Blue under UV irradiation of 254nm. Based on the 1st order reaction rate constant results the morphology N2:S2-MS has shown highest degradation followed by N:S1-MS. Overall, the photocatalytic activity order is N2:S2-MS andgt; N:S1-MS andgt; N:S2-CG andgt; N:S1-CG. In general, a significant variation in surface morphologies, crystal size and population, porosity and orientation were observed. This tailored-made variation enabled the doped ZnO thin films to successfully degrade the waste methylene blue effluents.

Sol-Gel Synthesized N and Mn Co-Doped TiO2 Nanomaterial for Photocatalytic Degradation of Malathion under Visible Light Irradiation

Different weight percentages (0.25-1.00 wt%) of Nitrogen (Non-Metal) and Manganese (Metal) co-doped nano titania were synthesized by sol-gel method and characterized by XRD, UV-vis.DRS, FT-IR, XPS, SEM and TEM. The XRD results has shown that all the prepared catalysts are in anatase phase indicating that co-doping of N and Mn did not affect the crystal structure of TiO2. From the UV-vis.DRS spectra a significant absorption shift towards visible region was noticed in N and Mn co-doped TiO2 and their presence was confirmed by XPS and FT-IR results. SEM and TEM results showed spherical nanoparticles with average particle size of 9 nm. Photocatalytic efficiency of synthesized nano materials was tested on non-biodegradable organophosphorous pesticide, Malathion under visible light irradiation. The effect of dopant concentration, pH, catalyst dosage, and initial pesticide concentration on photocatalytic degradation of malathion was studied and optimum conditions were established. Among the synthesized samples 0.50 wt% N & 1.00 wt% Mn-TiO2 exhibited best photocatalytic performance. Photoluminiscent spectroscopy (PL) was used to examine the rate of production of oxidative species, hydroxyl radicals which play key role in photocatalytic degradation.

Effect of dopant concentration on polyaniline/poly(4-styrene sulfonic acid) composite for ammonia gas detection

Polyaniline (PANI)/poly(4-styrene sulfonic acid) (PSS) has been prepared for various molar ratios of hydrochloric acid (HCl) (1, 2, 3 and 4 M, respectively) through in situ chemical polymerization method. The reaction temperature was 25°C for 3 h. Fourier transform infrared spectroscopy spectrum confirms the attachment of the structure to functional groups. The intensity of PANI is increased with increasing HCl concentration. Scanning electron microscopic graphs reveal the irregular morphology. The complex impedance of the PANI/PSS shows two distinguished semicircles and the diameter of the arcs decreased with an increase in ammonia concentration at room temperature. The sensitivity of the sensor increased with time, and the maximum sensitivity is 7.4 at 3 M of HCl for 500 ppm. The results are discussed and reported.

Piezo/triboelectric hybrid nanogenerators based on Ca-doped barium zirconate titanate embedded composite polymers for wearable electronics

Recently, hybrid nanogenerators (HNGs) based on the synergetic piezo/triboelectric effect have shown great promise for attaining high electrical output. In this work, microparticles (MPs) of calcium-doped barium zirconate titanate (Ca-BZT) are synthesized by a solid-state technique and subseqently dispersed into polydimethylsiloxane (PDMS) to prepare a composite film. This composite film is employed to develop an HNG device to efficiently harvest energy from various mechanical motions by individual piezoelectric or triboelectric effects, or a combined synergetic effect. The surface roughness, charge density, and dielectric permittivity of the composite films are significantly enhanced, resulting in an increase in output performance of the HNG device. The effect of Ca doping concentration on the ferroelectric characteristics of the BZT MPs and the output performance of the HNG device are systematically investigated. The BZT MPs with 2 mol% of Ca dopant optimize the high remnant polarization and piezoelectric coefficient of the Ca-BZT/PDMS composite. Moreover, the HNG device with the corresponding composite film also exhibits a maximum electrical output performance, with open-circuit voltage, short-circuit current, and power density values of 550 V, 34 μA, and 23.6 W/m2, respectively. Additionally, the mechanical stability and durability of the HNG device are investigated. To verify the practical applicability of the HNG, the generated output power is employed to demonstrate its ability to harvest biomedical energy and to power several light-emitting diodes as well as portable electronic devices.

Analysis of neodymium rare earth element doping in PbS films for opto-electronics applications

In this novel work, we discuss the effect of neodymium doping concentration on PbS thin films coated on glass substrates by a simple nebulizer spray pyrolysis method. The XRD analysis indicated that all the prepared PbS and PbS:Nd films possess polycrystalline simple cubic crystal structure along (200) preferential orientation and the estimated crystallites size tapered from 21 to 18 nm with growing Nd concentration. It is detected that Raman spectra of all films shows four characteristic mode at 186 cm−1, 281 cm−1, 326 cm−1, and 472 cm−1 certify the formation of PbS thin films. The micrographs obtained from scanning electron microscope indicated uniform particle on the surface of the films. Energy dispersive spectroscopy and mapping analyses confirmed the elemental composition. From the linear optical study by UV–Visible spectrometer exposed the absorption level of all the PbS:Nd films was constantly maintained in the whole visible and IR spectrum which is better for optical device fabrication. The rising of Nd content showed enhancement in band-gap as 2.13 to 2.41 eV. I–V characteristics of all the prepared films were done under dark and illumination conditions. Photosensitivity of the PbS films is enhanced after Nd doping, which result in enhancement of photo current. The results suggest that the proposed strategy can be applied to prepare high-performance photosensitivity thin films.

Concentration series of Sm3+-doped YVO4 nanoparticles: Structural, luminescence and thermal properties

Here, we report features of YVO4:Sm3+ nanocrystalline powders prepared via modified Pechini technique. Doping concentration effect on structural and luminescence properties has been studied in detail. XRD and Raman spectroscopy confirmed synthesis of single phase nanoparticles with no additional phase. SEM images showed that prepared nanophosphors have average size of 60 nm. Emission and excitation spectra of Sm3+-doped YVO4 nanocrystalline powders consisted of the characteristic lines corresponding to the intra-configurational f-f transitions dominated by electric dipole 4G5/2–6H9/2 transition. The optimal Sm3+ doping concentration was found to be dependent on excitation mechanism. Concentration quenching in YVO4:Sm3+ nanophosphors occurred via dipole–dipole interaction regardless of the excitation. Temperature effect on emission spectrum was investigated in terms of luminescence intensity and chromaticity coordinates. YVO4:Sm3+ nanoparticles have potential application in ratiometric luminescence thermometry. 4G5/2 lifetime gradually declined along with increase of Sm3+ ions amount.

Effects of Ce incorporation on the structural, morphological, optical, magnetic, and photocatalytic characteristics of ZnO nanoparticles

Research on semiconductors toward conventional electronic devices is limited owing to availability of more features in spin-based electronic devices, called spintronics. To provide optimal materials for spintronics, we studied the effect of Ce doping concentration on the crystalline, morphological, magnetic, and photocatalytic characteristics of ZnO nanoparticles. The particles were analyzed using x-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, field emission scanning electron microscopy, x-ray photoelectron spectroscopy (XPS), and with a vibrating sample magnetometer. In addition, we studied the degradation of methyl orange organic dye molecules. The wurtzite structure of the prepared nanoparticles and incorporation of dopant ions into the host lattice were confirmed by structural analysis. XPS results suggested that Ce ions were incorporated into the ZnO host lattice with +3 and +4 combined oxidization states and indicated the presence of oxygen vacancies. Room temperature magnetic hysteresis curves revealed that the Zn0.48Ce0.02O50 and Zn0.46Ce0.04O50 nanoparticles are superparamagnetic. Photocatalytic measurements confirmed that the synthesized nanoparticles of ZnO, Zn0.48Ce0.02O50, and Zn0.46Ce0.04O50 exhibit better degradation efficiencies through the decomposition of methyl orange molecules in aqueous media.

Effect of Fe doping concentration on photocatalytic performance of CeO2 from DFT insight into analysis

A series of CeO2 based materials are analyzed using first-principles calculation. After geometry optimization, the calculated parameter of Ce32O64 is in good agreement with the experimental and theoretical results. The lattice constant of doped materials becomes increasingly smaller with the introduction of more Fe doping into the lattice owing to the small radii of impurity atoms. Other data relate to increase or decrease to some extent. As for electronic property, the energy band structure and partial density of states are explored and discussed. Due to the enhancement of the degree of hybridization between O atoms and metal atoms, there is a narrower band gap in Fe doped materials, indicating that lower energy can promote and achieve electronic transition from the valence band to the conduction band. Through the complex dielectric function composed of the real part and the imaginary part, the extinction coefficient, it is observed that they are responsive to light and electronic transition under visible light irradiation. On the other hand, we predict the photocatalytic behavior by discussing the extinction coefficient. Besides, the optical absorption spectrum and optical band gap are analyzed to further observe performance in photocatalysis. It is found that doping causes first the red shift of the absorption edge and then results in the red shift and enhancement of photocatalytic performance, which is consistent with our prediction. In addition, Eopt indicates that Fe is beneficial for the activity of CeO2. The atomic number ratio of 3:1 (Fe:Ce) shows superior behavior compared to other materials.