Variation Of Doping Concentration Research Articles

Growth of Tin Oxide Thin Film by Aluminum and Fluorine Doping Using Spin Coating Sol-Gel Techniques

Abstract: The growth of tin oxide thin film by Aluminum doping and Fluorine has been carried out with the sol-gel spin coating technique. The growth aims to determine the quality of the thin layer formed based on variations in doping aluminum and fluorine. The basic ingredients used were SnCl2.2H2O, while the doping materials used were Al (Aluminium) and F (Fluorine) with variations in dopant concentrations (0, 5, 10, 15, 20 and 25)%. The growth of a thin layer using measured glass (10x10x 3) mm as a substrate. The growth of thin films includes substrate preparation, sol-gel making, thin film making, and heating processes. The growth of thin layer was dripped on a glass substrate with sol-gel spin coating technique at 1 M sol concentration and treated with maturation for 24 hours. The next step is making a thin layer using a spin coater at a speed of 2000 rpm for 3 minutes. After that, the substrate is heated in an oven at 100°C for 60 minutes. The results showed that the transparency level of the tin oxide layer increases with increasing amounts of doping Aluminum and fluorine. Key words: Aluminum, Fluorine, Sol-gel, Spin Coating, Thin Film, Tin Oxide

Improvement of TCAD Augmented Machine Learning Using Autoencoder for Semiconductor Variation Identification and Inverse Design

A machine learning (ML) model by combing two autoencoders and one linear regression model is proposed to avoid overfitting and to improve the accuracy of Technology Computer-Aided Design (TCAD)-augmented ML for semiconductor structural variation identification and inverse design, without using domain expertise. TCAD-augmented ML utilizes TCAD simulations to generate sufficient data for ML model development when experimental data are inadequate. The ML model can then be used to identify semiconductor structural variation for given experimental electrical measurements. In this study, the variation of layer thicknesses in the p-i-n diode is used as a demonstration. An ML model is developed to predict the diode layer thicknesses based on a given Current-Voltage (IV) curve. Although the variations of interest can be incorporated easily in TCAD simulations to generate ML training data, the TCAD-augmented ML model generally is overfitted and cannot predict the variations in experiment well due to hidden variables which also alters the IV curves. We show that by using an autoencoder, this problem can be solved. To verify the effectiveness, another set of TCAD simulation data is generated with hidden variables (dopant concentration variation) to emulate experimental data. Testing on the second set of data shows that the proposed model can avoid overfitting and has up to 15 times improvement in accuracy in thickness prediction. Moreover, this model is used successfully to perform inverse design and can capture an underlying physics that cannot be described by a simple physical parameter.

Chemical Trend of Transition-Metal Doping in WSe2

Transition-metal dichalcogenides (TMDs) are promising electronic materials for next-generation transistor and CMOS technologies. Here many challenges remain, though, including the ability to precisely control the type and density of free carriers in TMDs. This study uses first-principles calculations to provide important understanding of the experimentally observed large variation in attainable TM dopant concentration in bulk WSe${}_{2}$. The chemical trend found for the TM doping efficiency in the bulk compound should also be relevant to understanding doping and identifying more effective dopants in mono- or few-layer WSe${}_{2}$, and in other TMDs.

Electrical Properties of Barium Titanate Doped Lanthanum (Ba1-xLaxTiO3) Fabricated Using Co-precipitation Method

Barium Titanate doped Lanthanum (Ba1-xLaxTiO3) with variations in the concentration of mole dopants Lanthanum (x) 0; 0.01; 0.02; 0.03; 0.04 and 0.05 by co-precipitation method. Bulk BaTiO3 and Ba1-xLaxTiO3 were sintered at 1400 °C for 4 hours. The influence of variations concentration mole dopants of Lanthanum was analyzed through microstructure and electrical properties. The results of X-Ray Diffraction (XRD) analysis showed that the influence of variations concentration mole dopants of Lanthanum caused the diffraction angle to shift to the right. The influence of the variation concentration dopants mole of Lanthanum cause the dielectric constant to increase. The highest dielectric constant of 257.81 is obtained when the concentration of the La dopant mole is 5% (x=0.05) at a frequency of 40 kHz. The influence of Lanthanum dopant concentration variation on the morphology of the sample is that the more mole of dopant La added to BaTiO3 the smaller the size of the sample

Impact of uniform and non-uniform doping variations for ultrathin body junctionless FinFETs

In this paper, 3-D device simulations are performed to analyze the variations of uniform and non-uniformly (Gaussian) doped junctionless FinFETs. The impact of Fin width (Fw), Fin height (Fh), Channel length (Lg) and Gate Oxide (tox) on drain current, ION/IOFF ratio, subthreshold swing, Drain Induced Barrier Lowering (DIBL) of Si based Bulk Junctionless FinFETs is investigated. The results shows that the ION = 183μA/μm, IOFF = 4.449 × 10−5 μA/μm, is achieved for non-uniformly doping when compared to uniform doping configurations with ION = 102 μA/μm, IOFF = 3.05 × 10−5 μA/μm of junctionless FinFETs. Furthermore, the results also shows that non-uniformly doped junctionless FinFETs with fin width of 6 nm exhibits better DIBL of 22.5 mV/V and Subthreshold swing of 62.04 mV/decade than the uniform doped junctionless FinFET with DIBL of 80 mv/V and Subthreshold swing of 67.62 mV/decade. Thus, the non-uniformly doped junctionless FinFETs can effectively improve the performance of Junctionless FinFETs. In addition, to reduce the leakage current in bulk FinFETs effect of Punch-through Stop (PTS) layer, bulk doping concentration and body bias variations are studied. Finally, the 6T-SRAM circuit was implemented for JL-FinFETs and the results suggest that Gaussian doping JL-FinFETs strengthens the applicability of SRAM in the memory design.

D.C. conductivity behaviour of poly(vinyl alcohol)-based ferrogels: role of borax and carbonyl iron

The d.c. conductivity of poly(vinyl alcohol) hydrogels and ferrogels, cross-linked with borax, has been studied using two-probe resistance measurement method as a function of cross-linker and dopant concentrations. The availability of charge carriers (i.e. unbound borate ions and free sodium ions) in these matrices is seen to vary with cross-linker and dopant concentrations. Increase in borax concentration leads to the rise in d.c. conductivity values. Enhancement in the carbonyl iron dopant proportions, at unchanged borax concentrations, causes a decrease in the conductivity. This behaviour is explained on the basis of structural modifications introduced within the network matrix owing to the variations in cross-linker and dopant concentrations.

Impact of fin shapes and channel doping concentrations on the operation of junctionless transistors

The influence of variations in the Si fin shape on the electrical properties of junctionless transistors (JLTs) was investigated through two-dimensional Poisson equation numerical simulations at different doping concentrations. Stronger gate coupling in a triangular fin channel was observed, arising from suppression of the variation in the conduction threshold voltage with increasing doping concentration, compared to JLTs with rectangular fin channels. The potential distribution in the channel cross-section shows a less varied potential at the bottom of a triangular channel than at the bottom of a rectangular channel, and supports the result that triangular channels are less sensitive to variations in channel doping concentration.

Tuning of opto-electrical properties of hematite thin films using Co2+ doping

Hematite thin films have attracted widespread interest in recent years because of their advanced electronic and optical properties. Optical and electronic properties of hematite thin films can be enhanced/tuned using doping or additive-based strategies. An application oriented sol–gel method is used for the synthesis of cobalt (Co) doped hematite sol with variation in Co concentration in the range of 0–10 wt%. Hematite phase is observed in undoped thin films annealed at 300 °C under 500 Oe magnetic field for 60 min. Strengthening of hematite phase is observed with increase in Co concentration up to a value of 8 wt%. Bond angle with +ive tilt (i.e. ~ 19.74°) was observed in refined structural parameters for thin films prepared with Co concentration in the range of 0–8 wt%. Higher Co concentration, i.e. 10 wt%, results in decrease in crystallinity of the films along with smaller +ive tilt in bond angle (i.e. ~ 8.82°). High transmission (~ 88%) is observed for thin film prepared using dopant concentration of 8 wt% in the visible and infrared regions. The energy band gap varies from 2.42 to 2.25 eV with variation in Co concentration from 0 to 10 wt%. Relatively smaller band gap values are correlated with defect induced states in the band gap. Spectroscopic ellipsometry is used for calculation of refractive index and high values are indication of high density of thin films. Relatively higher value of dielectric constant (~ 183, log f = 5.0) along with lower value of tangent loss is observed at Co concentration of 8 wt%. Higher grain boundary resistance (1.88 × 105 Ω) was observed at 8 wt% Co concentration. Variation in d.c. conductivity with dopant concentration is studied in detail using Jonscher’s power law. The value of frequency exponent (n) lies in the range of 0.88–0.98 (< 1) with variation in dopant concentration signifying that motion of charge carriers involves translational motion along with sudden hopping process. It is important to mention here that combined tuning of optical and electrical properties are observed in the present study with no change in phase pure hematite crystallographic structure.

Study of an interesting physical mechanism of memory effect in nematic liquid crystal dispersed with quantum dots

ABSTRACTThe present study is based on effect of dispersing Cd1−xZnxS/ZnS core/shell quantum dots (QDs) on the memory behaviour of nematic liquid crystal 2020 with the variation of dopant concentration and applied voltage. Around 26% and 45% memory storage in QDs dispersed nematic matrix (MIX 1 and MIX 2) has been the core finding. The presence of ionic charges at low-frequency regime along with their reduction in QDs dispersed nematic matrix has been confirmed from tan δ curve. Pure nematic LC as well as nematic/QD mixtures depict volatile memory effect that depends upon concentration of QDs. The existence of memory due to storage of charge on QDs has been further confirmed from the dielectric, polarising optical micrographs and electro optical study under the influence of bias voltage. The observation of memory effect is attributed to the ion capturing and ion releasing phenomenon. The dispersion of QDs in nematic material plays an important role to enhance memory parameter by capturing and releasing the ionic charges under the application of bias voltage which has been confirmed from capacitance-voltage curve.

Photoluminescence and electrical conductivity measurement of liquid crystal doped with ZnO nanoparticles

ABSTRACTWe report the effect of dispersion of zinc oxide (ZnO) nanoparticles (NPs) on the conductivity, birefringence and fluorescence properties of commercially available room temperature nematic liquid crystal (LC) with the variation of dopant concentration. Significant changes have been observed in transition enthalpy, DC conductivity, photoluminescence and birefringence values of the LC material by the addition of ZnO NPs. While the inclusion of NPs enhances the electrical conductivity of the composite system, it results in a reduction in the birefringence value, which can be attributed to a decrease in the order parameter of the system due to the perturbed geometry of the LC. This also results in the increase in threshold voltage value, which has been speculated as due to the piezoelectric nature of the ZnO NPs. The analysis of the fluorescence spectrum indicates that ZnO NPs enhance the intensity in the LC phase along with a small blue shift.

Evaluation of Model for Determining Nitrogen Doping Concentration from Resultant Strain in Heavily Doped 4H-SiC Crystals

Lattice strain in 4H-SiC substrate wafers can strongly affect the performance of power electronic devices especially under the high temperature operation. The impurity incorporation in highly doped 4H-SiC crystals can result in significant lattice parameter change. Recently we reported [1] the synchrotron X-ray topographic contour mapping [2] technique to deconvolute lattice parameter variations from lattice tilt and thus generate strain maps. These strain maps have been incorporated into an anisotropic elasticity model to derive the nitrogen doping concentration variation in the 4H-SiC wafer. Doping distribution can be derived using a set of anisotropic strain maps detected by recording series of diffraction contours across the same region. The nondestructive contour mapping method we developed is capable of not only determining the concentration but also the distribution of the doping i.e. a doping map. In order to verify the doping level determined by contour mapping, we prepared samples with different N-doping levels. Contacts were created by depositing Ni using e-beam evaporator followed by rapid annealing. Hall effect measurements have been carried out on these samples to measure the carrier concentration in order to determine the doping values. The measured values are found to be in good agreement with the doping map derived using our contour mapping method. Reference Yu Yang, Jianqiu Guo, Balaji Raghothamachar, Xiaojun Chan, Taejin Kim, Michael Dudley, J. Electron. Mater. 47(2), 938-943 (2018).J. Guo, Y. Yang, B. Raghothamachar, M. Dudley, and S. Stoupin, J. Electron. Mater. 47(2), 903-909 (2018).

Synthesis and characterization of Y and Dy co-doped ceria solid electrolytes for IT-SOFCs: a microwave sintering

In this communication, the electrical conductivities and thermal expansion studies of microwave sintered co-doped ceria Ce0.8Y0.2−xDy x O2−δ (x = 0, 0.05, 0.10, 0.15 and 0.20) solid electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) synthesized by sol–gel auto-combustion method were discussed. Microwave sintering at 1300 °C for 30 min was used for making dense powder compacts. The relative densities of all the samples are noticed above 95%. Raman spectrum was characterized by the presence of a very strong band near 460 cm−1, which along with X-ray diffraction (XRD) analysis ascertain the sample formation with a single-phase cubic fluorite structure. The lattice parameter values were calculated from XRD patterns. SEM images show nearly uniform grains with distinct grain boundaries. The thermal expansion coefficients (TECs) are found to vary linearly with temperature and were measured in the range from 14.15 to 13.20 × 10−6 °C−1. The investigation on total ionic conductivity (TIC) was executed with variation in dopant concentration and relative oxygen vacancies. The impedance analysis reveals that the sample Ce0.80Y0.10Dy0.10O2−δ displays the highest TIC, i.e., 7.5 × 10−3 S·cm−1 at 500 °C and minimum activation energy 0.90 eV compared to others. With the highest TIC and minimum activation energy, the Ce0.80Y0.10Dy0.10O2−δ might be the possible material as the solid electrolyte in intermediate temperature SOFCs.

Anisotropic Microsegregation in the Growth of Doped III‐V‐Semiconductors from Solution

AbstractIn this paper, a consistent formulation of macro‐ and microsegregation is presented to describe dopant inhomogeneities and concentration variations in binary and multinary III‐V‐semiconductor crystals grown from metallic solution. The effective distribution and diffusion coefficients respectively are calculated by applying the classical segregation models for zone melting and are based on experimental data. From the macroscopic effective distribution coefficient keff the microscopic kinetic distribution coefficient kkin is derived, which varies along a curved growth face, in particular along a macrostep. As a consequence of this surface anisotropy, the fluxes of the dissolved species through the interface vary as well and cause local changes in the liquidus distribution of species. The liquidus concentration is calculated by means of 2‐dimesional numerical simulations. The extracted liquidus concentration along the interface combined with the locally changing kinetic distribution coefficient allows the calculation of the solidus concentration along the macrostep. The result is the consistent description of microsegregation as a result of an anisotropic interface on a µm‐scale and the macro‐segregation on a mm‐ or cm‐scale. This could be tested experimentally in a diffusion dominated growth regime under microgravity.

Penumbuhan Film SnO2 Dengan Doping Al-Zn Menggunakan Teknik Sol-Gel Dip Coating

Al-Zn doped SnO2 (Sn1-2xAlxZnxO2) film has been growth using the sol-gel dip coating technique. The basic materials used in this study were water, C2H5OH, SnCl2.2H2O, AlCl3 and ZnCl2 with 99% purity (merck) with doping concentration variation x = 0.000, 0.005, 0.025, and 0.050. Glass substrate with size 2.54 mm x 76.2 mm x 1 mm cleaned with detergent, soaked in 30% HCl solution For 1 day and dried at 100°C. The process of making a SnO2 sol is done by mixing the precursor with various concentrations with water and stirring using a magnetic stirrer for 30 minutes at a temperature of 80 ° C. The next step by adding ethanol, stirring at 80 ° C. for 2 hours to obtain 0.4 M sol solution The deposition of SnO2 film was carried out using a dip coater with a whitdrawl speed 12 cm/min and then heated for nucleation and grown using an electric furnace at 600 ° C for 30 minutes. This step is repeated as much as 5 repetitions to get the SnO2 film by doing Al-Zn.

Characterization of Strain Due to Nitrogen Doping Concentration Variations in Heavy Doped 4H-SiC

Highly doped 4H-SiC will show a significant lattice parameter difference with respect to the undoped material. We have applied the recently developed monochromatic contour mapping technique for 4H-SiC crystals to a 4H-SiC wafer crystal characterized by nitrogen doping concentration variation across the whole sample surface using a synchrotron monochromatic x-ray beam. Strain maps of 0008 and − 2203 planes were derived by deconvoluting the lattice parameter variations from the lattice tilt. Analysis reveals markedly different strain values within and out of the basal plane indicating the strain induced by nitrogen doping is anisotropic in the 4H-SiC hexagonal crystal structure. The highest strain calculated along growth direction [0001] and along [1-100] on the closed packed basal plane is up to − 4 × 10−4 and − 2.7 × 10−3, respectively. Using an anisotropic elasticity model by separating the whole bulk crystal into numerous identical rectangular prism units, the measured strain was related to the doping concentration and the calculated highest nitrogen level inside wafer crystal was determined to be 1.5 × 1020 cm−3. This is in agreement with observation of double Shockley stacking faults in the highly doped region that are predicted to nucleate at nitrogen levels above 2 × 1019 cm−3.

Synthesis of ZnO Nanoparticles Doped Zirconium Oxychloride by PSTA BATAN Yogyakarta Production as Photoanode Semiconduktors for Dye Sensitized Solar Cell

Dye Sensitized Solar Cell (DSSC) is a device for light conversion to be electrical energy based on the concept of semiconducting sensitivity of the wide gap. This study aims to synthesis nanoparticles of ZnO: Zr semiconductors and tested the performance of ZnO: Zr nanoparticles on the DSSC system. ZnO Doped Zr Nanoparticles from precursor by Science and Technology Acceleration Center of National Nuclear Energy Agency (PSTA BATAN) Yogyakarta production was synthesized by gel-combustion method, and tested its performance on DSSC system. Effect of doping concentration variation Zr (0, 1, 3 and 5%) on the structure crystals and optical properties of ZnO studied by X-ray diffraction, infra-red spectra, and UV-Visible absorbance spectra. In this study also studied about the effect of Zr doping on changes in the parameters of crystal structures such as distances between fields of crystals , crystals lattice (a and c), unit cell volume, crystallite size, microstrain (ε), dislocation density (δ), and the textural coefficient . The synthesized nanoparticles meet the criteria 3-dimensional nanostructure of hexagonal wurtzite crystals. Uptake ZnO infrared radiation shows an increase in intensity as well shift in wave number 610 - 400 due to doping Zr. Doping Zr also influences the electronic structure of semiconductors characterized by the change of bandgap energy from 3,10-3,05 eV. Semiconductor performance test nanoparticles on the DSSC system showed a 1% Zr doping concentration increasing the voltage by 174 mV and the stability of the solar cell than the cell ZnO solar without doping that produces a voltage of 128 mV.

Studies on Doping Concentration Variations in 4H-SiC Substrates Using X-ray Contour Mapping

4H-SiC is one of the promising wide bandgap material that attracts considerable attention in power electronics industry. Several applications have benefited from the improved performances of devices made of 4H-SiC in terms of its higher breakdown fields, efficiency and reliability as well as excellent physical properties. However, the widespread commercialization of this material is still being hindered by the various defects introduced during the crystal growth which is found to degrade the device performance and lifetime. Stacking faults, for example, have been considered to be one of the most detrimental structural defects. It has been predicted theoretically that high nitrogen doping concentration level (above 2 x 1019cm-3) inside 4H-SiC crystal will increase propensity for formation of stacking faults. These can create quantum wells which can lower the free energy of the whole crystal once the barrier for partial dislocation motion is overcome by thermal energy (achieved by annealing above 1000o C) [1-2]. Moreover, from a perspective of high power electronic applications, other severe issues, such as inhomogeneous resistivity and a large {0001} surface roughness of substrate are characteristic of heavily nitrogen doped SiC crystal [3]. It is known that, the nitrogen incorporation kinetic is anisotropic in different crystallographic directions during PVT growth of SiC. Therefore, better understanding the nitrogen doping distribution inside the material is important. In our experiments, we conducted X-ray topographic contour mapping [4] using synchrotron monochromatic X-ray beam by rocking the heavily doped wafer surface successively with a fixed angular step size around the near-surface diffraction vectors 0008 and -0008 respectively. From these measurements, a strain map can be derived by deconvoluting the lattice parameter variations from the lattice tilt. The nitrogen doping concentration can be calculated from the isotropic lattice strain due to the incorporation of dopants according to the equation from H. Jacobson [5]. [1] Y. Yang, J. Guo, Ouloide Goue, B. Raghothamachar, M. Dudley, G. Chung, E. Sanchez, J. Quast, I. Manning, and D. Hansen, J. Crystal Growth, 452, 32 (2016). [2] T.A. Kuhr, J. Liu, H. J. Chung et al., Journal of Applied Physics,92, 5863 (2002). [3] N. Ohtani, M. Katsuno, M. Nakabayashi, T. Fujimoto et al., J. Crystal Growth, 311, 1475 (2009). [4] S. R. Stock, Haydn Chen and H. K. Birnbaum, Philosophical Magzine A, 53(1), 73(1986). [5] H. Jacobson, J. Birch, C. Hallin, A. Henry, R. Yakimova, T. Tuomi, E. Janzén, and U. Lindefelt, Applied Physics Letters 82 (21), 3689 (2003). Figure 1

Studies on Doping Concentration Variations in 4H-SiC Substrates Using X-ray Contour Mapping

Highly doped 4H-SiC will show a significant lattice parameter difference with respect to the undoped material. We have applied the recently developed monochromatic contour mapping technique for 4H-SiC crystals to a 4H-SiC wafer crystal characterized by nitrogen doping concentration variation across the whole sample surface using the synchrotron monochromatic X-ray beam. Strain maps of 0008 and -2203 planes were derived by deconvoluting the lattice parameter variations from the lattice tilt. Analysis reveals markedly different strain values within and out of the basal plane indicating the strain induced by nitrogen doping is anisotropic in the 4H-SiC hexagonal crystal structure. The highest strain calculated along growth direction [0001] and along [1-100] on the closed packed basal plane is up to -4x10-4 and -2.7x10-3 respectively. Using an anisotropic elasticity model by separating the whole bulk crystal into numerous identical rectangular prism units, the measured strain was related to the doping concentration and the calculated highest nitrogen level inside wafer crystal was determined to be 1.5x1020cm-3. This is in agreement with observation of double Shockley stacking faults in the highly doped region that are predicted to nucleate at nitrogen levels above 2x1019 cm-3.

Visible light-emission from Eu-doped ZnAl layered-double hydroxide

Abstract We report on the evolution of the emission and chemical properties of Eu-doped ZnAl-Layered double hydroxide (LDH) with variation of Eu doping concentration during the hydrothermal growth. With increasing Eu source concentration, the morphologies of the ZnAl-LDHs became denser and more closely packed while maintaining the thickness of each plate. As the Eu source concentration increased to 10 wt%, specific emission from the doped Eu 3+ ions was enhanced in the photoluminescence spectra. However, the peak intensity decreased when the concentration increased further to 20 and 30 wt%. X-ray photoelectron spectroscopy results showed an abnormal increase of the Eu 2+ /Eu 3+ ratio in the LDHs with increasing Eu source concentration, which suppressed the emission from the Eu 3+ electronic transitions.

CdTe quantum dot dispersed ferroelectric liquid crystal: Transient memory with faster optical response and quenching of photoluminescence

In the present study, the effect of dispersing Octadecylamine capped Cadmium Telluride quantum dots (CdTe QDs) on the memory behaviour, physical parameters and dielectric relaxations of ferroelectric liquid crystal (FLC) W-327 with the variation of dopant concentration and applied voltage has been examined. Significant changes have been observed in visible light absorbance, photoluminescence (PL), spontaneous polarization, optical response and relative permittivity of the FLC material with the addition of QDs. An average of 19% (Mix.1) and 28% (Mix.2) fastening of optical response in QDs dispersed FLC mixtures was one of the remarkable findings. Enhancement in visible absorbance along with the quenching in PL intensity has also been noticed in FLC/QD mixtures in comparison to pure FLC. The study of tan δ curves confirms the reduction of ionic impurities in the presence of QDs. Pure FLC as well as FLC/QD mixtures show time dependent memory effects. The memory behaviour of mixtures significantly depends upon the concentration of dopant CdTe. The memory effect was confirmed with the help of dielectric spectroscopy, polarizing optical micrographs and electro-optical study. The observed memory effect has been attributed to minimization of the depolarization field and ionic charges. The QDs dispersed FLC plays a major role to enhance memory effects by trapping the impurity ions under the application of bias voltage. These studies would be helpful to provide an idea for ionic impurity free memory devices having micro-second optical response and in security coded transmission.