Higher Wavelength Region Research Articles

Effect of dipolar state on J-type aggregation of acceptor group modified pyrene-based push-pull systems

The present work demonstrates the ground and excited state aggregation behavior of two pyrene-based push–pull systems (Pyr-MC and Pyr-PyA) both in solid and solution state. The UV–Vis spectra of these molecules show a unique broaden spectral pattern at lower energy region (400–600 nm) in both H2O and solid state. Further, along with the local (intense) emission band, a new (less intense) band is appeared at higher wavelength region (∼550 nm) in water, which is due to the formation of aggregates. Interestingly, it is the lowest energy emission out of all previously reported emission by pyrene derivatives. The experimental results suggest the formation of J-type aggregation in solid and solution. The average lifetime of these molecules is also measured in different solvents. Intriguingly, the ground/excited state J-type aggregation in solid and solution are similar in nature in spite of different mode of intermolecular interactions, and are supported by experimental results. The dipolar state plays an important role on the J-type aggregation process. The QTAIM (quantum theory of atom in molecule) theoretical framework is applied to analyze and understand the properties of molecules in terms of the distribution of electrons and the topological features of the electron density within a molecule. Importantly, bond paths provide information about the nature of chemical bonds, including their strength and directionality.

To Study the Cadmium Sulphide Thin Films Synthesis by Simple Spin Coating Method for Energy Application

The paper examines the properties of CdS thin film, which is used for window material of solar cells and optical devices. The cadmium sulfide (CdS) thin film was prepared by sol-gel method on glass and ITO substrate. Prepared thin film dried in a vacuum oven at 70℃. Thin film and powder of CdS characterized for structural, optical, and electrical properties by X-ray Diffractometer (XRD), UV-Visible spectrometer, and Keithley spectrometer. The average crystallite sizes, microstrain, and dislocation density of the samples were calculated by the Debye Scherrer formula. The optical band gap of CdS calculated by the Tauc-plot method and obtained 2.40 and 2.41eV for powder and film. The absorption wavelength of CdS is suddenly decreased near 280nm and becomes flat in the higher wavelength region. The FTIR spectrometer is used to identification of unknown materials and bond formation. The bond formation, imperfections, and impurities were observed by the PL spectrometer. Keithley spectrometer is used for I-V characteristics and calculates electrical resistivity by Ohms law.

Nonlinear optical studies of phenothiazine Schiff bases for optical limiting application

Synthesized Schiff-based organic molecules consisting of phenothiazine backbone (Phe-DNP, Phe-Ma, Phe-3) to investigate its optical limiting applications. The structural confirmation of compounds is carried out by FTIR and NMR spectroscopy. The quantum mechanical calculations of compounds are measured using Density functional theory (DFT) to investigate the electronic orientation in molecular orbitals and the theoretical bandgap. All the molecules show a broad absorption in the visible domain and the conjugated molecule absorption shifts towards the higher wavelength region. The effective intramolecular charge transfer of molecules in the order Phe-DNP> Phe-Ma>Phe-3 is understood from the ground state absorption spectra results. All the organic moieties exhibited sequential two-photon absorption upon studying the open aperture Z-scan technique. Phe-Ma molecule shows the highest nonlinear absorption (1.212× 10−10 m/W) and lowest optical limiting threshold (3.19 × 1012 W/m2) compared to other molecules suggesting that Phe-Ma could be a potential nonlinear optical limiter.

Excitation wavelength altered PL study of Co doped ZnO nanoparticles suitable for white LED application

Abstract ZnO nanoparticles doped with Co at different concentration (Zn1−x Co x O) were synthesized by sol–gel auto combustion method and are characterized by using various characterization tools. Structural study using X-ray diffraction technique (XRD) analysis showed the crystalline nature with hexagonal wurtzite geometry and the composition analysis using energy dispersive X-ray spectroscopy (EDX) confirmed the incorporation of Co in the ZnO lattice in the case of doped nanoparticles. Scanning electron-microscopy (SEM) and transmission electron microscopy (TEM) analysis showed the prepared nanoparticles as spherical, loosely agglomerated and having dimension of nanoscale. UV–vis DRS studies indicated a red shift in optical band gap with Co doping. PL spectra exhibits emission in the UV and visible region and the analysis revealed information about the presence of various types of defects in the ZnO lattice. An increase in the excitation wavelength gives intense emission in the high wavelength region for doped nanoparticles confirming the presence of divalent and monovalent oxygen as main defects. The Zn0.93Co0.07O nanoparticles records CIE coordinates lying in the white region of CIE color space at 350 nm with CCT of 5561.4 K suggesting their suitability in fabrication of white light emitting diodes.

Numerical modelling of 1-dimensional silicon photonic crystal sensor for hydrostatic pressure measurement

Abstract In this work, a highly sensitive hydrostatic pressure sensor using one-dimensional (1D) photonic-crystal (PC) is designed and analyzed numerically for its sensing performance. The device design has silicon (Si) sensing layer at the top to sense the applied pressure. The proposed sensor performance has been studied for its pressure sensing, by applying boundary load on the sensing layer. The structure is designed, simulated and analyzed using an FEM tool. As the applied pressure is varied from 0 MPa to 10 MPa, resonant mode shifts towards the higher wavelength region. The effect of defect cavity length and the number of periods are also analyzed to choose the optimized value which enhances the sensor performance parameters. Simulation result shows that the proposed sensor has a very high sensitivity of 250 nm/GPa and Q-factor of 11,120 with the transmission of 99.99%.

1-Dimensional silicon photonic crystal pressure sensor for the measurement of low pressure

In this article we proposed a one-dimensional (1D) silicon photonic-crystal (PC) as a highly sensitive pressure sensor to measure the applied hydrostatic pressure. A 1D flexible silicon layer is formed at the top of the proposed structure. The proposed sensor is designed to measure the low pressure in the range of 10kpa to 20kpa. An FEM tool Comsol Multiphysics is used to design, simulate and analyze the structure. A central cavity is created to support the resonant mode and shift in the resonant mode is observed with the varying boundary load. With the variation in the applied pressure from 10kpa to 20kpa, shift in the resonant mode towards higher wavelength region was observed. The defect cavity length and number of layers were tuned to get optimized results. The novelty of this work includes, use of silicon material to sense the applied pressure, design and its simulation to obtain electric field distribution in the multi-layer structure and its analysis for sensing the applied boundary load using an FEM tool. Simulation results shows that the proposed sensor has a very high sensitivity of 350 nm/GPa and Q-factor of 40,104 with the transmission of 99.99 %.

Extraction of Optical Constants and Dispersion Parameters of CdTe/CdSe Bi-Layer Thin Films

The current study focuses on the annealing-induced changes in the optical constants and dispersion parameters of the CdTe/CdSe bi-layer films deposited onto glass substrates by thermal evaporation technique. The slight shift in transmission threshold towards higher wavelength region with increasing annealing temperature revealed the systematic reduction in optical energy band gap (1.92 to 1.37 eV) of the films. The dispersion curve of the refractive index shows an anomalous dispersion in the absorption region and a normal dispersion in the transparent region. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion parameters and dielectric constants were evaluated. The increase in the refractive index with the annealing temperature modified the other linear parameters such as optical density, dissipation factor, volume, and surface energy loss function. The increase in the optical conductivity value is good for the CdSe film to be used as a semitransparent solar cells absorbing layer.We have made an attempt to discuss and correlate these results with the annealing temperature of possible mechanisms underlying the phenomena.

Modifications in the structural, morphological, optical properties of Ag45Se40Te15 thin films by proton ion irradiation for optoelectronics and nonlinear applications

This current work reports the 30 keV proton ion irradiation induced structural, morphological, and optical properties change in Ag45Se40Te15 films at different fluences. The thin films were irradiated with different ion fluences, such as 5 × 1015 ions/cm2,1 × 1016 ions/cm2 and 5 × 1016 ions/cm2. The electronic loss (Se) dominates over the nuclear loss (Sn) in proton irradiation. The X-ray diffraction study shows the phase transformation from amorphous to crystalline upon ion irradiation. The Raman analysis confirms the change in chemical and vibrational bonds due to structural alterations in the films. The surface morphology has been studied by field emission scanning electron microscopy and the composition of the films has been checked by the energy dispersive X-ray analysis. The particle size increased upon the increase in ion irradiation fluence. The surface roughness of the films has been studied by atomic force microscopy. The transmission data is used to calculate the linear optical parameters. The absorption edge shifts towards the high wavelength region inferring the reduction in the optical bandgap. The linear refractive index of the films increased with ion fluence. The optical density increased at the high wavelength region while the skin depth decreased with fluence. The carrier concentration per effective mass decreased while the plasma frequency increased with proton irradiation. The nonlinearity (χ (3) and n2) values increased significantly with the increase in fluences. Such kind of materials with optimization in their optical parameters are primarily essential for cutting-edge photonic, optoelectronic, and nonlinear optical applications.

TiO2–CU Thin Film Material for Optical Hydrogen Gas Sensor Applications

Purpose: Several scientific researches are underway to investigate the possibility of using various green energies. Hydrogen gas is a candidate of such research, since its use as a fuel in automobiles releases pure water, a recyclable biproduct. But, the leakages of the gas are detrimental to its application due to its low auto ignition energy of 20 μj, wider air flame limit of 4-75 % and high flame velocity of 3.46 ms-1. This study involved fabrication of an optical gas sensor for sensing the leakage levels of hydrogen gas to a surrounding.
 Methodology: Titanium dioxide thin films of thicknesses 47.7, 56.2, 82.3, 100.4 and 120.5 nm were deposited on both microscope and FTO glass slides using DC magnetron sputtering technique and characterized as primate and annealed at 400 and 500oC. Copper (Cu) catalytic layers of 5.6, 10.2, 17.3 and 21.0 nm were deposited using EDWARDS AUTO 306 Magnetron sputtering system on an optimized 100.4 nm TiO2 sample, annealed at 400oC. Optical properties were deduced from transmittance and absorbance spectra measured using 1800 Shimadzu spectrophotometer in the optimum range of 280-800 nm through simulation. The optical behavior of the films was generated using SCOUT software and analyzed using ORIGIN 9.1 64-bit software.
 Results: The energy band gap decreased with material thickness from 4.2±0.05 eV for 47.7 nm film to 3.9±0.05 eV for 100.4 nm films. 120.5 nm films showed higher energy gap of 4.0±0.05 eV. Transmittance decreased with increase in thickness probably due to agglomeration of film particles. The energy gap of the 100.4 nm, TiO2 thin films annealed at 400oC was 3.9±0.05 eV. This is a material quality of the anatase phase. The copper surface layer increased absorption in the higher wavelength region. The energy band gaps were reduced from 3.9 to 3.8±0.05 eV with increased coverage. Self-limiting at 17.3 nm copper overlayer realized increased energy gap to 4.1±0.05 eV. A lower energy band gap range of 3.9-3.8±0.05 eV was realized when FTO substrates were used. The transmittance decreased with increased H2 gas concentration. The optical energy gap reduced from 4.1±0.05 eV in 0 ccm to 3.9±0.05 eV in 50 ccm of hydrogen gas concentration. The sensitivity increased from 0.3 % in 0ccm to 3.9 % in 50 ccm hydrogen gas concentration. An average sensitivity of 2.0 % was realized for films fabricated on FTO substrate. This is higher than 1.7 % reported earlier. The material gas sensing potential was done at room temperature. The fabricated sensor material showed higher sensitivity and lower temperature operation and is furthermore, expected to be cheaper and safer
 Unique Contribution to Theory, Policy and Practices: Though, in order to realize a more portable stand-alone gas sensor, an investigation on an ideal photon type source that incorporates the material is recommended. Further, extension of this study on structure and morphology of the film is essential to understand its sensing behavior.

Impact of high energy ion irradiation on structural, morphological, optical and photoluminescence properties of MgTiO3 thin films

High energy ion irradiation induced effects on structural, morphological, optical, and luminescent properties of MgTiO3 (MTO) thin films were investigated. Films were irradiated using Si and Au ions with energies 80 and 120 MeV, respectively, at two different fluences of 1 × 1012 and 1 × 1013 ions/cm2. The reduction in peak intensity and a slight shift in peak position as observed in XRD pattern with increase in fluence, indicate the decrease in crystallinity and generation of lattice strain, respectively. Films were completely amorphized upon irradiation with Au ions at a fluence of 1 × 1013 ions/cm2. A reduction in root-mean-square roughness is observed after ion beam irradiation. Au irradiated samples possess slightly higher roughness as compared to Si irradiated ones. The large electronic energy loss in Au irradiated films results in generation of more number of defects causing a greater shrinkage in bandgap. Transmittance of Si irradiated samples is lesser than pristine films, while Au irradiated samples possess slightly higher transmittance as compared to Si irradiated films. Intense photoluminescence emission in UV region with a few weak peaks in higher wavelength region is observed. Irradiation induces broadening and reduction in peak intensities with fluence. The average decay lifetime of photogenerated carriers in pristine and irradiated films is in nanoseconds regime.

Photonic cavity mode tuning in porous silicon-based microcavities by He+ and H+ ion irradiation

The present investigation reports the optical characteristics of the porous Si (PSi) based microcavities before and after energetic He+ and H+ ion irradiations. These PSi microcavities were fabricated by the galvanostatic electrochemical etching process and irradiated with 35 keV He+ and H+ ions with three different ion fluences: 1 × 1015, 5 × 1015, and 1 × 1016 ions/cm2. Significant color contrast is evident in the reflection images after ion irradiation. These reflection spectra of the optical microcavities are systematically investigated before and after ion irradiations. The dominant resonant cavity peak of the microcavity shows a notable shift of ∼28–48 and ∼17–26 nm toward the higher wavelength region with He+ and H+ ion irradiations at various ion fluences, respectively. The relative changes in the cavity wavelengths are about ∼5%–10% and ∼3%–5% for He+ and H+ ion irradiations, respectively. The redshift in the reflectance spectra is attributed to modification in the refractive index of microcavities induced by He+ and H+ ions. These experimental results compare well with the ion propagation and transfer matrix method simulations. The observed changes in the optical properties arise due to surface modification of the Si–Si and Si–O bonds and thereby refractive index modification of individual PSi layers of the microcavity. This study establishes that low-energetic ions produce broadly optically tunable and photonic structures suitable for optoelectronic applications.

Photocatalytic Degradation of Congo Red and Methyl Orange Dye Under Visible Light Using Silver and Iron co-doped TiO2 Nanoparticles

In the present report TiO2 nanoparticles co-doped with iron and different mol % of silver have been successfully synthesized by sol-gel route and studied by X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), UV-visible absorption spectroscopy (UV-Vis), Photoluminescence spectroscopy (PL), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), and FTIR spectroscopy. The XRD data analysis confirms the formation of mixed phases of TiO2 (anatase) and Ag2O phase. The crystalline size was vary from 48.0 nm to 44.6 nm determined from XRD further verified from TEM micrograph. The EDXS measurements suggest that iron is completely incorporated however silver has not incorporated into TiO2 matrix. The optical band gap of the prepared nanoparticles was calculated by UV-Visible absorption spectroscopy using Tauc-Davis and Mott expression and found to varying from 2.92 to 2.30 eV. The absorption bands in the UV-visible spectra shift towards higher wave length region and appearance of emission bands in PL spectra confirms the formation of energy substates in the forbidden gap of the prepared samples. TEM micrographs showed that prepared nanoparticles are somewhat spherical in shape. The formation of different functional groups and bonds in the structure of synthesized nanoparticles as observed in FTIR spectra helps in degradation of organic dyes (congo red and methyl orange) and enhance the photocatalytic activity under visible light. It is observed that the higher doping concentration of silver causes to decrease the band gap energy as a result the carrier recombination rate decreases and therefore enhance the degradation efficiency.

Structural and optical properties of undoped and Sb-doped lead oxide thin films synthesized via the chemical bath deposition method

Undoped PbO thin films and various concentrations of Sb ranging from 1 to 9 at% were prepared on borosilicate glass substrates by a chemical bath deposition method. The structural characteristics detected were amorphous, owing to the trend of glass formability based on a small amount of Sb in the PbO thin film. The mixed phases of tetragonal (α-PbO) and orthorhombic (β-PbO) were clearly observed at the 3, 5, 7, and 9 at% Sb concentrations. A significantly higher value in average root-mean-square (RMS) roughness was revealed for various Sb-treated PbO thin films. The highest average RMS roughness for the 7 at% Sb-doped PbO thin film was obtained due to the largest nucleation and coalescence process of the nanoparticles. The average Eg can be estimated to be 2.49, 2.58, 2.34, 2.46, 2.46, and 2.19 eV for 0, 1, 3, 5, 7, and 9 at% Sb-doped PbO thin films, respectively. This change or fluctuation in average Eg can be explained from the disorder in the thin films and is correlated with the growth of PbO nanostructures. The optical constants, dielectric constants, and dielectric loss functions were derived from the extinction coefficient (k), and refractive index (n). The highest linear susceptibility (χ(1)), nonlinear susceptibility (χ(3)), and nonlinear refractive index (n2) values in the low wavelength region (300–700 nm) and the high wavelength region (700–1100 nm) were respectively obtained for the undoped PbO and the 7 at% Sb-doped PbO thin film. These have important and promising implications for optical devices in the wavelength range from UV to NIR. Finally, the calculated Egs, with the Perdew-Burke-Ernzerhof (PBE) function, are 1.79 eV and 2.44 eV for the undoped α and β phases, while the Egs of the Sb-doped α and β phases are reduced to 1.61 eV and 2.10 eV, respectively.

The impact of fluence dependent proton ion irradiation on the structural and optical properties of Bi5In30Se65 thin films for nonlinear optical devices.

This paper reports the effects of ion irradiation on the structural, linear, and nonlinear optical properties of thermally evaporated Bi5In30Se65 thin films. The prepared films were irradiated with 30 keV proton ions with different fluences, such as 5 × 1015 ions per cm2, 1 × 1016 ions per cm2, and 5 × 1016 ions per cm2. Structural analysis via X-ray diffraction (XRD) confirmed the non-crystalline nature of the film after ion irradiation with different doses. However, after the irradiation dose, the surface morphology changed, as shown by atomic force microscopy (AFM) images and field emission scanning electron microscopy (FESEM) images. The compositions of the films were obtained using energy-dispersive X-ray spectroscopy (EDX). Optical analysis via UV-Visible spectroscopy showed a reduction in the transmittance and an increase in the absorption in the higher wavelength region with irradiation. The optical bandgap and Tauc parameter decreased with an increase in the irradiation fluence, which is due to an increase in the irradiation-induced defects and disorder inside the system. The increases in the third order nonlinear susceptibility and the nonlinear refractive index with ion fluence are useful for nonlinear optical applications. The linear refractive index calculated from the transmittance data increased, satisfying Moss's rule. The optical parameters, such as lattice dielectric constant, optical density, skin depth, optical conductivity, real and imaginary dielectric constants, optical conductivity, loss factor, VELF, and SELF, were calculated using several empirical relationships and showed increasing behavior with the ion irradiation dose. The changes obtained in both the linear and nonlinear parameters will be useful for nonlinear optical device applications.

The structural and optical properties of Ag/Cu co-doped BiVO4 material: A density functional study

Density Functional Theory (DFT) calculation was used to conduct a systematic theoretical study on the structural, electrical, and optical properties of pure, Ag-doped, Cu-doped, and (Ag, Cu) co-doped BiVO4. The simulated electronic structure showed that the synergistic effect of Ag/Cu co-doping can induce new energy states due to hybridization in the forbidden gap that resulted in decrease in the band gap of BiVO4, which indicates a decline in photogenerated electron-hole pair recombination and an understandable shift of absorption edge towards higher wavelength region. The (Ag, Cu) co-doped BiVO4 has a higher optical absorption intensity than pure Ag or Cu doped BiVO4, demonstrating the synergistic effect of Ag 4d and Cu 3d states. Furthermore, DFT calculations have been analyzed to explore the collective effect of Ag or/and Cu doping and the intrinsic oxygen vacancy defects in BiVO4.

A Comparative Analysis of Pressure Sensing Parameters for Two Dimensional Photonic Crystal Sensors Based on Si and GaAs

A pressure sensor based on two dimensional photonic crystal structure is presented. The structure considered for sensing is a lattice of air holes surrounded by semiconductor material. A waveguide with central microcavity is formed by filling air holes with semiconductor material. The sensing principle depends upon the shifting of central wavelength of peak towards higher wavelength region when the pressure is raised. The proposed pressure sensor can work in the range 0–5 GPa. Using this structure, two semiconductors, Si and GaAs, have been taken for analysis. It is found that shifting of resonant wavelength with pressure is more pronounced in GaAs than Si. In the dynamic range 0–5 GPa, sensitivity for sensor with Si is estimated as 1.674 nm/GPa while it is 17.00 nm/GPa for sensor with GaAs. The quality factor and figure of merit (FOM) is also found to be higher for GaAs sensor.

Synthesis and Properties of Polyimide Silica Nanocomposite Film with High Transparent and Radiation Resistance.

In order to prepare flexible glass cover sheet materials suitable for space solar cells, fluorinated diamine 2,2’-bistrifluoromethyl benzidine (TFDB) and fluorinated dianhydride 4,4’ (hexafluoroisopropyl) diphthalic dianhydride (6FDA) as the monomer, polyimide (PI)/SiO2 composite film was synthesized by in situ polymerization, and the influence of coupling agent and SiO2 nanoparticle content on the film structure and properties was studied. The results show that PI synthesized from fluorine-containing monomers has better light transmittance, and the highest transmittance can reach 91.4%. The average visible light transmittance of the composite film decreases with the increase of SiO2 content, and the transmittance of the film decreases less in the high-wavelength region and greatly decreases in the low-wavelength region. The tensile strength and elastic modulus of PI/SiO2 composite film increase with the increase of SiO2 content, first increase and then decrease, reaching the maximum when the content is 10%; while the elongation at break of the composite film gradually increases with the increase of SiO2 content reduce. The thermal stability of PI/SiO2 composite film increases with the increase of SiO2 content. The doping of nano-SiO2 significantly suppresses the influence of irradiation on the mechanical properties of the film.

Structural, Optical and Dielectric Properties of Nd Doped NiO Thin Films Deposited with a Spray Pyrolysis Method

The effect of Nd doping (1, 3 and 5 wt%) on the structural, morphological, electrical and optical properties of NiO thin films deposited on glass substrates using nebulizer spray pyrolysis method are investigated. The X-ray diffraction study reveals cubic structure with an improvement in crystallinity upon the incorporation of Nd into NiO lattice. The films are > 50% transparent in the high wavelength region. The absorption spectra witnesses a sharp fall in the wavelength range, 300 nm < λ < 600 nm reflecting the semiconducting nature of these films. The optical direct (indirect) band gap values obtained using Tauc’s relation decrease from 3.67 eV (3.00 eV) for pure NiO to 3.38 eV (2.44 eV) for 3 wt% Nd:NiO. The linear refractive index (n) values estimated using different models are compared. Using the average linear refractive index along with optical direct band gap, the high-frequency and static dielectric constants; the linear and non-linear optical susceptibilities and non-linear refractive index are calculated. It is observed that all these quantities enhance with Nd doping whereas the static dielectric constant decreases with an increase in Nd content. The high frequency dielectric constant and static dielectric constant values are observed to vary between 5.08–5.45 and 51–32, respectively. The values of linear and non-linear optical susceptibilities and non-linear refractive index are found vary between 0.325–0.354, 1.90 × 10–12–2.67 × 10–12 esu and 3.17 × 10–11–4.31 × 10–11 esu, respectively.

Tuning the properties of Cd1-xMnxS films deposited by nebulized spray pyrolysis

The present work describes different properties of Cd1-xMnxS (x = 0.04, 0.06, 0.08, 0.10 and 0.20) thin films deposited on glass substrate at 300 and 400 °C by a simple nebulized spray technique. The X-ray diffraction study evident that the intensity of hexagonal (002) plane is decreased with increase in Mn concentration. The appearance of peaks corresponding to Cd, Mn, and S in X-ray photoelectron spectroscopic data confirmed the compositional purity of deposited films. It is observed from the scanning electron microscopic images that the films are having the surface with distribution of particles and clear grain boundaries with some pores. The root mean square surface roughness of the film was found to be 15.6 nm (for x = 0.04) and 11.07 nm (for x = 0.20). The Raman spectra of Cd1-xMnxS (with x = 0.06, 0.08 and 0.20) films deposited at 300 and 400 °C exhibit the first longitudinal optical phonon (1LO) peak at 300 cm−1 and the second longitudinal optical phonon (2LO) peak at 600 cm−1. From the transmittance spectra, it is observed that the transmittance threshold shift towards higher wavelength region with increasing substrate temperature and Mn concentration, which indicates the systematic reduction in optical energy band gap (Eg) of the films. The decrease in the band gap is mainly arised due to the sp-d exchange interaction between the CdS band electrons and localized d-electron associated with Mn2+ cation. The magnetic properties of Cd1-xMnxS are modified because of the sp-d exchange interactions between localized d-electrons of the dopant and the mobile charge carriers in the host lattice.

Theoretical and simulation study in defective semiconductor layer that incorporated with superconducting-dielectric photonic crystal

In this work, the transfer matrix method (TMM) is used to calculate the transmission of superconductor-dielectric 1D photonic crystal with central defect of semiconductor material (GaAs) at high superconductor critical temperature ([Formula: see text]. It is noticed that there is a red shift to high wavelength region by increasing the thickness of constituent materials. Also we study the effect of changing the incident angle, the doping density of GaAs and the applied pressure. The results show that the sense and change of photonic bandgap and transmittance peaks based on the thickness, incident angle, doping density of GaAs and hydrostatic pressure. In the case of change the thickness and hydrostatic pressure, the PBG and peak of transmittance shifted to higher wavelengths (red shift), while in the case of changing the incident angle and doping density, the PBG and peak of transmittance shifted to shorter wavelengths (blue shift).