Effect Of Doping Concentration Research Articles

Effective atomic number and photon buildup factor of bismuth doped tissue for photon and particles beam interaction

Abstract Introduction: The doping of high Z nanoparticles into the tumor tissue increases the therapeutic efficiency of radiotherapy called nanoparticle enhanced radiotherapy (NERT). In the present study, we are identifying the effective types of radiation and effective doping concentration of bismuth radiosensitizer for NERT application by analyzing effective atomic number (Zeff) and photon buildup factor (PBF) of bismuth (Bi) doped soft tissue for the photon, electron, proton, alpha particle, and carbon ion interactions. Material and methods: The direct method was used for the calculation of Zeff for photon and electron beams (10 keV-30 MeV). The phy-X/ZeXTRa software was utilized for the particle beams such as proton, alpha particle, and carbon ions (1-15 MeV). Bismuth doping concentrations of 5, 10, 15, 20, 25 and 30 mg/g were considered. The PBF was calculated over 15 keV-15 MeV energies using phy-X/PSD software. Results: The low energy photon (<100 keV) interaction with a higher concentration of Bi dopped tissue gives the higher values of Zeff. The Zeff increased with the doping concentration of bismuth for all types of radiation. The Zeff was dependent on the type of radiation, the energy of radiation, and the concentration of Bi doping. The particle beams such as electron, proton, alpha particle, and carbon ion interaction gives the less values of Zeff has compared to photon beam interaction. On the other hand, the photon buildup factor values were decreased while increasing the Bi doping concentration. Conclusions: According to Zeff and PBF, the low energy photon and higher concentration of radiosensitizer are the most effective for nanoparticle enhanced radiotherapy application. Based on the calculated values of Zeff, the particle beams such as electron, proton, alpha particle, and carbon ions were less effective for NERT application. The presented values of Zeff and PBF are useful for the radiation dosimetry in NERT.

Effect of dopant concentration on the optical characteristics of Cr3+:ZnGa2O4 transparent ceramics exhibiting persistent luminescence

ZnGa2O4 (ZGO) persistent luminescence (PersL) ceramics doped with different concentrations of Cr3+ were prepared by the co-precipitation method and hot isostatic pressing (HIP) post-treatment. After HIP post-treatment, the ZGO PersL ceramics was significantly improved from opaque to transparent visual appearance due to the elimination of micro-pores during HIP process. The effects of Cr3+ concentration on the morphology, transmittance and PersL properties of ZGO PersL ceramics were systematically investigated. The ZGO PersL ceramics with higher Cr3+ dopant concentrations show less micro-pores and higher transmittance, which indicates that the Cr3+ can also work as a sintering additive to increase the density and to improve the optical quality of ZGO PersL ceramics. The photoluminescence excitation (PLE) and emission (PL) intensities increase with the increase of Cr3+ concentration up to 0.25 at.%. At yet higher Cr3+ concentrations, the ZGO PersL ceramics exhibits weaker PL and PLE intensities which is probably caused by the concentration quenching effect. However, the PersL decay curves show that the PersL performance of ZGO ceramics increases with increasing Cr3+ concentrations, indicating that the doping by Cr3+ ions may cause another traps formation leading to stronger and longer PersL. The PersL decay curves of all ZGO PersL ceramics were fitted by the second-order exponential function, indicating that at least two kinds of traps with different electron release rates exist in the ZGO ceramics. The influence of Cr3+ concentration on the thermoluminescence (TL) of ZGO PersL ceramics was also studied, and the results showed that the TL curves of the pre-sintered ceramics shifted to lower temperatures, indicating that the depth of trap related to Cr3+ ions is shallower than the depth of trap caused by the intrinsic defects.

A comprehensive study on structure, opto-nonlinear and photoluminescence properties of Co3O4 nanostructured thin films: An effect of Gd doping concentrations

Cobalt oxide (Co3O4) thin films with 0, 1.0, 3.0 and 5.0 wt% Gd doping concentrations were fabricated on glass substrates by spray pyrolysis method. X-ray diffraction pattern (XRD) of as-deposited thin films confirm spinel structure growth oriented along (311) plane. Crystallite sizes of the grown films decreases with the increase in Gd doping concentrations and found in range of ∼17.7–7.2 nm. Raman investigation of films further approves spinel growth of cobalt oxide films. Surface morphology of pure and Gd: Co3O4 thin films were analyzed using field emission scanning electron microscopy (FESEM) with round shape particles at nanoscale. Chemical compositions, elements, and their stoichiometry were observed by energy dispersive spectra (EDX). Tauc's plots of films clearly shows two direct optical band gaps, (1) in the range of 1.49–1.52 eV and (2) in the range of 2.01 eV–2.58 eV respectively. A significant impact of Gd doping was observed on second optical band gaps, which increases with Gd contents. Room temperature (RT) dependent photoluminescence (PL) spectra of the deposited films showed that emission peaks at 363, and 753 nm under excitation wavelength of 240 and 500 nm respectively. The third order nonlinear optical susceptibility χ(3) and nonlinear refractive n(2) which were calculated and found in range 4.46 × 10−13- 2.25 × 10−10 esu and 1.01 × 10−10-2.39 × 10−9 esu., respectively.

Theoretical and Experimental Investigate for the Magnetic and Optical Properties of Mn-ZnO Nanowire Microspheres

A Mn-ZnO nanowire microsphere was prepared by using the hydrothermal method. The effects of Mn doping concentration and hydrothermal growth conditions on the crystal structures, morphologies, magnetic and optical properties of ZnO nanowire microsphere were studied. The characterization results showed Mn-ZnO nanowire microsphere with uniform and dense distributions along the [0001] direction with a hexagonal wurtzite structure. No impurity phases were detected in microsphere specimens. The room-temperature ferromagnetism of the Mn-ZnO nanowire microsphere was detected, with the saturation magnetization of 2.4 × 10−1 emu/g and a coercive field of 369 Oe. Furthermore, with the increase of Mn2+ ions doping concentration, the luminescence intensity of the sample decreases in both UV and visible regions, and slight blueshift in the visible light regions was observed. The theoretical results presented obvious spin polarization near the Fermi level, with strong Mn 3d and O 2p hybridization effects. The magnetic moments were mainly generated by Mn 3d and partial contribution of O 2p orbital electrons. Therefore, the Mn-ZnO nanowire microsphere can be used as a potential magneto-optical material.

Rational design, fabrication, optical properties and high-efficiency visible-light photocatalytic degradation performance for organic pollutants of Eu:Bi2WO6/CdS nanostructures

Over the past few years, semiconductor materials (especially bismuth tungstate) exhibiting unique environment purification and energy conversion capacities arouse huge attention as impacted by issues of environmental pollution and energy shortage, whereas its application is restricted by the problems of high carrier recombination rate and unsatisfactory degradation efficiency. In this study, Eu:Bi 2 WO 6 nanostructures containing Eu ions of different concentrations were synthesized with a chemical solution method, and CdS was generated on the surface of Eu:Bi 2 WO 6 nanostructures in situ epitaxial to synthesize the Eu:Bi 2 WO 6 /CdS composites. The effects of Eu doping concentration on the crystal structure, chemical composition, local structure, optical properties and visible-light photocatalytic properties exhibited by Eu:Bi 2 WO 6 /CdS nanostructures were studied more specifically, and the Eu doping behavior on the improvement mechanisms for optical and photocatalytic performance exhibited by Eu:Bi 2 WO 6 /CdS nanostructures was clarified. The robust PL emission peak at about 390 nm and weak emission peak at nearly 450 nm are attributed to the exciton emission and defect state of Bi 2 WO 6 /CdS nanostructure, respectively. As indicated from the mechanism insights, the reasonable introduction of Eu 3+ could alter the band gap of the photocatalyst, and the epitaxial CdS could decrease the recombination probability of electron and hole in the Bi 2 WO 6 /CdS, while improving the photocatalytic activity. This study supplies new occasions for rational excogitation and better comprehending of atomic-scale complicated structures for applications in numerous fields (e.g., energy and environmental protection).

The Effects of Dopant Concentration on the Performances of the a-SiOx:H(p)/a-Si:H(i1)/a-Si:H(i2)/µc-Si:H(n) Heterojunction Solar Cell

In this work, the imbalances in band gap energy between p-window layer and intrinsic layer (p/i interface) in p-i-n type solar cells to suppress charge recombination adopting with the addition of buffer layer, at p/i interface, namely solar cell structures without buffer (Cell A) and with buffer (Cell B). Using well-practiced AFORS-HET software, performances of Cell A and Cell B structures are evaluated and compared to experimental data. A good agreement between AFORS-HET modelling and experimental data was obtained for Cell A (error = 1.02%) and Cell B (error = 0.07%), respectively. The effects of dopant concentrations of the p-type and n-type were examined with respect to cell B for better performance by analysing the energy band diagram, the electric field distribution, the trapped hole density, the light J-V characteristics, and the external quantum efficiency. The simulated results of an optimised Cell B showed that the highest efficiency of 8.81% (VOC = 1042 mV, JSC = 10.08 mA/cm2, FF = 83.85%) has been obtained for the optimum dopant values of NA = 1.0 x 1019 cm-3 and ND = 1.0 x 1019 cm-3, respectively. A comparison between experimental data and simulation results for Cell B showed that the conversion efficiency can be enhanced from 5.61% to 8.81%, using the optimized values

Radiation Effects in Ultraviolet Sensitive Pd/4H-SiC Schottky Detectors

4H-SiC, by virtue of its intrinsic properties, is a very promising semiconductor material for fabricating rad-hard UV detectors suitable for harsh radiation environments. This paper aims to investigate the radiation tolerance of indigenously developed Pd/4H-SiC Schottky detectors, in order to determine their feasibility for space applications. 4H-SiC detectors of active area 1 × 1 mm2 were irradiated with electrons of energy 10 MeV at fluence of 2×1013 e-/cm2 and gamma rays from a Co-60 source with a total dose of 1 Mrad. The impact of these irradiations on electro-optical characteristics of the devices was studied by analyzing the changes in electrical parameters like reverse saturation current (Is), ideality factor (n), barrier height (ɸB), effective doping concentration (Neff) derived from I-V and C-V characteristics as well as in the UV spectral responsivity (i.e., from 248 to 365 nm) of the irradiated detectors. The electron irradiated device showed negligible change in I-V and C-V characteristics whereas its UV spectral responsivity at the peak wavelength of 290 nm reduced by 48.7 %. Gamma irradiated device displayed a noticeable variation in its electrical characteristics and 15.8 % reduction in the spectral responsivity (optical characteristics) at the peak wavelength. The results show that the radiation hardness of 4H-SiC detectors is better than that of conventional semiconductor ones, making it a more appealing choice as radiation detectors in space systems.

Analysis of Subthreshold Swing of Symmetric Junctionless Double Gate MOSFET Using Gaussian Doping Profile

—The variation of subthreshold swing(SS) according to the projected range (Rp ) and standard projected deviation (σp ) was analyzed when the symmetrical junctionless double gate (JLDG) MOSFET was doped with Gaussian doping profile. For this purpose, the analytical SS model was presented. We compared with the TCAD results to turn out the validity of this model, and the SSs of this model agreed with those of TCAD. The effective conduction path and mean doping concentration affecting the SS were analyzed according to the Rp and σp . As a result, the SS increased as the Rp and σp increased simultaneously. The smaller the Rp and the larger the σp , the lower the SS. When Rp = 1.5 nm, it showed the SS below 100mV/dec without being affected by the change of σp or silicon thickness. When σp = 3nm, it was also 100mV/dec or less regardless of the change of Rp and silicon thickness. Keywords— Double gate, Junctionless, Subthreshold swing, Gaussian, Projected range, Standard projected deviation

Structural and Optical Studies of Synthesized Semiconductor NixZn1-xS Nanostructure Thin Films for Optoelectronic Device Applications

Transition metal ions like Nickel doped ZnS semiconductor materials have a wide range of optoelectronic device applications. However, the doping concentration effect on the properties of NixZn1-xS has not been reported. This study, therefore, investigated the effects of nickel (Ni) doping concentration on the structural and optical properties of synthesized NixZn1-xS nanostructured thin films prepared by low-cost Chemical Spray Pyrolysis (CSP) technique. NixZn1-xS nanostructured thin films with a thickness of 320nm and different mole ratios (𝑥 = 0.00, 0.02, 0.04, 0.06 and 0.08,) were grown by the use of spray solution on hot glass substrates at a temperature of 300oC using CSP technique. The spray solutions contain nickel acetate, zinc acetate, and thiourea as precursors for Nickel, Zinc, and Sulphur, respectively. The influence of Ni doping concentration on the structural, optical, and morphological properties were investigated using X-ray diffraction (XRD), Ultraviolet-Visible spectroscopy (UV-vis) and Scanning Electron Microscopy (SEM) respectively. The XRD analysis indicated that all the prepared films retained the ZnS cubic zinc blend structure. SEM results show that the films are composed of well crystalline grains with various shapes and densely bound to each other. The UV-vis spectroscopy shows that transmittance is moderately high and increased with increasing Ni content. The average transmittance of NixZn1-xS are 61.3%, 62.8%, 63.9%, 67.6 and 69.6% for x = 0.00, 0.02, 0.04, 0.06 and 0.08, respectively. The bandgap of Ni-doped ZnS samples is low compared to the undoped, and the value increases gradually with increasing Ni concentration. Based on the results obtained, with the enhanced structural and optical properties, NixZn1-xS films could be a useful material in the future of optoelectronic applications.

Structural and spectroscopic studies of V2O5 incorporated lithium-bismuth-boro-tellurite glass ceramics

The effect of dopant concentration on the spectroscopic characteristics of multi-component glass ceramics with the composition 25Li2O-(15-x) Bi2O3-45B2O3-15TeO2-xV2O5(x = 0, 2, 5, 7, 10 mol %) fabricated using traditional melt-quenching process is shown in this study. The prepared glass ceramics were extensively characterised using XRD, FTIR, EPR, etc. The x-ray diffraction (XRD) study reveals that the glasses were semi-crystalline (ceramic) in nature. In addition, Rietveld refinement was used to investigate the crystalline component in the glass network that is responsible for a ceramic nature of the prepared samples. Structural results reveal that the Bi2O3 was found in the crystalline cubic structure of 2 and 5 mol% V2O5 doped glass systems. In other words, the incorporation of V2O5 into the host glass matrix alters the structure of the glass, resulting in semi-crystallization of glass samples. Surprisingly, crystalline structure of LBBTV samples decreases as the V2O5 concentration was increased, owing to the stabilizing of the glass structure at higher doping concentrations. Physical parameters for instance, molar volume is in accordance (decreases till 5 mol % and then increases) with the XRD data. As the vanadium content increases, the FTIR spectra indicate a drastic shift in borate units. EPR spectra of glass ceramics and glasses show resonance signals typical of VO2+ ions.

Mechanism and principle of doping: realizing of silver incorporation in CdS thin film via doping concentration effect.

A high-quality buffer layer serves as one of the most significant issues that influences the efficiency of solar cells. Doping in semiconductors is an important strategy that can be used to control the reaction growth. In this study, the influence of Ag doping on the morphological, optical and electrical properties of CdS thin films have been obtained. Herein, we propose the mechanism of CdS film formation with and without Ag ions, and we found that changes in the reaction of preparing CdS by the chemical bath deposition (CBD) method cause a shift in the geometric composition of the CdS film. XRD showed that the position of peaks in the doped films are displaced to wider angles, indicating a drop in the crystal lattice constant. The optical analysis confirmed direct transition with an optical energy gap between 2.10 and 2.43 eV. The morphological studies show conglomerates with inhomogeneously distributed spherical grains with an increase of the Ag ratio. The electrical data revealed that the annealed Ag-doped CdS with 5% Ag has the highest carrier concentration (3.28 × 1015 cm-3) and the lowest resistivity (45.2 Ω cm). According to the results, the optimal Ag ratio was obtained at Ag 5%, which encourages the usage of CdS in this ratio as an efficient buffer layer on photovoltaic devices.

Effect of ortho-phosphoric acid doping concentration on electrochemical properties of polyaniline coated low carbon steel

Conducting polyaniline-based paint formulation is prepared and coated on the low carbon steel samples. Characterization of conducting polyaniline showed the characteristic peak at 327 nm and a weak broad peak at 608 nm under UV–Vis’s spectrometry. The effect of doping level on electrochemical performance of conducting polyaniline painted low carbon steel was studied using ortho-phosphoric acid as a dopant. All polyaniline-based painted steel samples exhibited a shift in corrosion potential positively and a reduction in corrosion rate. However, the corrosion rate of 0.3 M ortho- phosphoric doped conducting polyaniline coated low carbon steel sample is found to be 0.01 mpy, significantly lower than that of painted and unpainted samples. Higher impedance modulus, coating resistance, and lower coating capacitance confirm the corrosion resistance of 0.3 M ortho-phosphoric doped conducting polyaniline coated low carbon steel sample in a neutral medium. It reveals that doping plays an essential role in the electrochemical performance of the painted steel samples and protects the steel by a barrier and anodic protection.

Structural, optical and antibacterial performance of the Mg doped TiO2 nanoparticles synthesized using sol–gel method

Mg doped TiO2 nanoparticles were synthesized by chemical based sol–gel techniques is to investigate the effects of Mg doping concentration on the structural, optical, antibacterial and luminescence properties of TiO2 nanoparticles. Pure and doped TiO2 samples of various concentration were annealed at 400 °C to achieve the desired phase of crystalline structure. XRD results reveals that the prepared samples were exhibits crystalline nature. The crystallite size was observed around 9.7 nm which decreased to 6.8 nm with an increase the doping concentration of Mg. Optical transmittance increases from 80% to 90% and optical band gap varies from 3 eV to 3.07 eV with doping of Mg in TiO2. The photoluminescence emission exhibit in near UV to blue resign from the pure and doped TiO2 nanoparticles. Red shift observed in PL bands. Antibacterial activity was also examined and studied the effects of concentration on the performance. The tuning the properties of TiO2 with doping of Mg have been discussed in details.

Improving photovoltaic performance of P3HT: IC60BA based organic solar cell: N-type doping effect

In this paper we report a numerical simulation study for P3HT: IC60BA based organic solar cell with Analysis of Microelectronic and Photonic Structures the simulation one dimension software (AMPS-1D). Indeed, the N-type doping concentration (ND) effect on the organic solar cell performance is done. Moreover, a combination between the P-type doping concentration (NA) and N-type one (ND) is investigated. However, due to the relationship between doping and carriers charge mobility, the effect of ND for different electron mobilities (μn) is also studied. We showed a high efficiency of 5.88% that is achieved for particular values of NA = 1017 cm−3, ND = 2 × 1016 cm−3, μp = 3 × 10−4 cm2 V−1 s−1 and μn = 7 × 10−4 cm2 V−1 s−1. Thus, we noticed that the P-type doping remains more promising than N-type one for the device performance improvement. Furthermore, the validation of the obtained results by those experimentally reported in literature is realized. In addition, the doping of other BHJ OSC devices consisting of P3HT: IC70BA is studied; an optimum efficiency of about 6.32% is reached.

Influence of dopant concentration on the ammonia sensing performance of citric acid-doped polyvinyl acetate nanofibers.

The chemical modification of polymer nanofiber-based ammonia sensors by introducing dopants into the active layers has been proven as one of the low-cost routes to enhance their sensing performance. Herein, we investigate the influence of different citric acid (CA) concentrations on electrospun polyvinyl acetate (PVAc) nanofibers coated on quartz crystal microbalance (QCM) transducers as gravimetric ammonia sensors. The developed CA-doped PVAc nanofiber sensors are tested against various concentrations of ammonia vapors, in which their key sensing performance parameters (i.e., sensitivity, limit of detection (LOD), limit of quantification (LOQ), and repeatability) are studied in detail. The sensitivity and LOD values of 1.34 Hz ppm-1 and 1 ppm, respectively, can be obtained during ammonia exposure assessment. Adding CA dopants with a higher concentration not only increases the sensor sensitivity linearly, but also prolongs both response and recovery times. This finding allows us to better understand the dopant concentration effect, which subsequently can result in an appropriate strategy for manufacturing high-performance portable nanofiber-based sensing devices.

Enhanced dielectric and electrical properties of PbS nanostructures facilely synthesized by low-cost chemical route: An effect of Ce doping concentrations

Herein the authors are presenting the facile preparation and characterization of Ce doped PbS nanostructures (Ce@PbS NSs). Phase analysis was studied by X-ray diffraction which approves major cubic phase of PbS along with CeClS phase peaks. Vibrational analysis also confirm major cubic phase of PbS of the final products. EDX/SEM e-mapping showed the Ce doping with homogeneity in PbS. SEM analysis gives a clear morphology of nanoparticles along with some nanoflakes in respective pure and doped PbS. Optical study reveals the variation in energy gap values of PbS with Ce content from 1.45 eV (pure PbS) to 1.084 eV (2.5 wt% Ce@PbS) and also there is another energy gap varies between 3 and 3.5 eV in pure and doped PbS NSs. The capacitance and impedance were studied over wide frequency region. The dielectric constant of PbS has been improved from 17.5 to 24.5 with Ce content addition. The ac electrical conductivity was improved with Ce content addition in PbS. The improvement in dc-electrical conductivity was also noticed with Ce addition in PbS. The improved dielectric and electrical characteristics makes the synthesized Ce@PbS NSs useful in optoelectronic.

Atomistic simulations of acceptor removal in p-type Si irradiated with neutrons

The effective dopant concentration in p-type Si detectors reduces with irradiation fluence at low fluences due to the acceptor removal process, which degrades detector performance and shortens its lifetime. This effect has been experimentally characterized and parametrized, but its microscopic origin is still unknown. We use atomistic simulations to gain insight into acceptor removal in neutron irradiation by modeling damage generation and defect-dopant interactions. We analyze the effect on dopant deactivation of the Si di- and tri-interstitial diffusion, the inhomogeneity of irradiation damage and the wafer temperature rise during irradiation. We characterize defect generation rates and identify the relevant defect-dopant interactions. Acceptor removal occurs mainly through the formation of Bi pairs and small boron-interstitial clusters, and it is limited by the availability of mobile Si interstitials. The presence of impurities (O, C) modifies B-complexes favoring the formation of BiO, but has a limited effect on the amount of removed acceptors.

Effect of Sn doping concentration on the oxidation of Al-containing MAX phase (Ti3AlC2) combining simulation with experiment

Sn doping is usually adopted to prepare Ti3AlC2 in mass production because it can reduce the synthesis temperature while increasing the phase purity. However, excessive Sn doping usually deteriorates the oxidation resistance of Ti3AlC2. Therefore, an appropriate Sn doping concentration is a vital issue. In this work, the effect of Sn doping concentration on the oxidation behavior of Ti3AlC2 was systematically investigated by combining theoretical calculations and experimental methods. Density function theory calculations suggest that the oxygen adsorption mechanisms for the (001) surface of Ti3AlC2 with and without Sn doping are similar, and Ti-O bonds are always preferentially formed. The molecular dynamics simulation further indicates that Al atoms have a faster diffusion rate during the oxidation process. Therefore, a continuous Al2O3 layer can form rapidly at high temperature. Nevertheless, when the Sn doping concentration exceeds 10 mol%, the continuity of the Al2O3 layer is destroyed, thereby impairing the oxidation resistance of Ti3AlC2. Furthermore, oxidation experiments verify the above results. The oxidation mechanisms of Ti3AlC2 with different Sn doping concentrations are also proposed.

Investigation of nitrogen doped ZnO thin films: Effects on their structural and optical properties

Un-doped and nitrogen-doped ZnO thin films were grown by using radio frequency (RF) magnetron sputtering method changing the nitrogen flow rate between 0% −12.5% and the thickness dependence of films was determined. The effect of nitrogen doping concentration on the structural, morphological, and optical properties of zinc oxide thin films was studied. X-ray diffraction (XRD) analysis confirmed that the nitrogen-doped ZnO films belong to the hexagonal crystal structure. The optical properties of the grown samples were examined by optical spectrophotometer and spectroscopic ellipsometer. Transmittance spectra were obtained by spectrophotometer measurements and the effect of nitrogen ratio was investigated. It has been observed that as the nitrogen ratio increases, the transmittance decreases up to ∼500 nm and then increases. By using the transmittance curve, the energy band gap was calculated. Further detailed optical analysis was made by the spectroscopic ellipsometry technique. Fitting was performed to ensure the agreement between the experimentally obtained Ψ values and theoretically determined Ψ values using the Cauchy model. As a result, the refractive index was found for each film and it was observed that the refractive index decreased as the nitrogen ratio increased. The scanning electron microscopy (SEM) measurements showed that the surface morphology of the films changes with N doping. Nitrogen was observed in Fourier transform infrared spectra analysis. 5% nitrogen-doped ZnO films were grown on the glass substrate using RF magnetron sputtering at room temperature. Samples are prepared by varying thicknesses during the deposition process. XRD and SEM measurements of the samples show the variation in the crystal structure and surface morphology of the film with varying thicknesses. All the samples are tested for the transmittance and band gap. The increase of film thickness increases the grain size. The transmittance is influenced by the film thickness. • Un-doped and nitrogen doped ZnO thin films were grown by using RF magnetron sputtering method. • The band gap values were changed by changing N doping. • The refractive index values of ZnO films decrease with the introduction of nitrogen into the structure. • The band gaps decreased from 3.25 eV to 3.20 eV as the thickness increased. • Zn–N bonds were attributed at ∼1380 and ∼1502 cm −1 .

Effect of Al doping on the electronic structure and optical properties of germanene

The effects of different doping concentrations and hydrogenation on the electronic structure and optical properties of Al-doped germanene were studied based on a density generalised theory first-principles approach. It was found that the system with a doping concentration of 3.125% was more stable. The bandgap is lower than 0.1 eV for doping concentrations of 3.125% to 6.25%, which is consistent with the nature of semimetals. The bandgap transition from indirect-direct-indirect is achieved at doping concentrations of 11.11% to 25%. Both the s- and p-states of Al and Ge atoms contribute to the total density of states compared to the intrinsic germanene, and the doping of Al promotes the absorption and reflection of light from germanene and also undergoes different degrees of blue shift. Hydrogenation has a large effect on the electronic structure of Al-doped germanene, making the s and p state's electronic interactions of Al atoms weaker. The Al-doped germanene system can be converted from indirect bandgap to direct bandgap when fully hydrogenated.