Irradiated Thin Films Research Articles

Investigation of gamma-ray irradiation induced phase change from NiO to Ni2O3 for enhancing photocatalytic performance

An Irradiated nickel oxide (NiO) thin film was deposited onto glass substrates at 723 K by the spray pyrolysis using nickel chloride as precursors. The obtained films were irradiated by gamma-radiation doses varying from 180 Gy to 10 kGy. The structure and optical properties of the samples were examined by X-ray diffraction, UV–vis spectrometer and photoluminescence measurement. Un-irradiated and irradiated NiO thin films have a cubic structure with the same preferred orientation along the plane (111). XRD investigation shows that, the intensity of preferred orientation and crystallite size depend on gamma-radiation dose. For a study of the dose effect, it is very important to optimize the precursor concentration. With a concentration of 5.10−2M precursor NiCl2 and a dose of 10 kGy, we obtain a thin film of Ni2O3. With a 10 kGy dose we obtain a new dominant phase, Ni2O3, which induced an activation of the visible range under the effect of gamma rays. This improved the photocatalytic performance under gamma rays treatment. Moreover, the PL quenching effect shows an improvement of photocatalytic properties.

Chromium oxide formation on nanosecond and femtosecond laser irradiated thin chromium films

Thin coatings of Cr2O3 have been used for numerous applications. Selective oxidation of chromium will be beneficial for integrated device fabrications. Thin coatings of pure chromium were vacuum deposited on a glass substrate using hot electrons from tungsten filament. These coatings were then treated with nanosecond and femtosecond laser in ambient conditions. The microstructure, morphology and the color of the coatings treated with laser sources were modified and there was a formation of an oxide layer due to the heat dissipation on the chromium coating from the energetic photons. High-resolution scanning electron microscope studies showed the morphological evolution, which is directly correlated with the laser fluence of both the nanosecond and femtosecond lasers. This morphological evolution was accompanied by the microstructural change as observed from the X-ray diffraction patterns. The chromaticity response of the coating was studied by UV–Vis spectroscopy and the response of the coating in the visible region evolved with the laser fluences. The divergence in chromaticity of these two laser treatments, is due to the difference in morphology as the result of the varied pulse duration. It could be concluded that the morphology had effect on the chromaticity of the films. Futhermore, Rutherford backscattering depth profiling of the laser treated coatings revealed the diffusion of oxygen atoms in the coating as a result of laser treatment fluence. We have analyzed both the optical and material properties of the laser induced oxidation and demonstrated laser writing as a promising tool to selectively oxidize Chromium for integrated device applications.

High-energy 120 MeV Au9+ ion beam-induced modifications and evaluation of craters in surface morphology of SnO2 and TiO2 nanocomposite thin films

The electronic excitation and modification in the properties of the target material occur due to the kinetic energy loss of incident ions mainly through the inelastic collision with atomic electrons in the process of electronic energy stopping. Nanocomposite tin oxide (SnO2) and titanium dioxide (TiO2) thin film were grown on silicon and ITO substrates using RF magnetron-sputtering process. These thin films were irradiated by 120 MeV Au9+ Swift Heavy Ion (SHI) beam with varying fluence from 5 × 1011 ions cm−2 to 2 × 1013 ions cm−2 to induce modifications in thin films by dense electronic excitation. Surface morphology and depth profile of craters (approx. 85 nm) have been characterized by multimode atomic force microscopy (AFM). Grain mapping of AFM images provided the variation in grain size in the range of 72–279 nm and RMS roughness increased (4.01–23.6 nm) with increasing the ion fluence. Scanning Electron Microscopy (SEM) was also carried out to confirm the formation of craters in the irradiated film. X-ray diffraction (XRD) technique has been used for the structural analysis of virgin and irradiated thin films. XRD patterns established the formation of film in mixed (rutile and gamma) phase. Further, the crystallite size was evaluated using the Debye–Scherrer and Williamson–Hall method. It was found that crystallite size lie in the range of 36–54 nm which increased for the lower fluence and then decreased for higher fluence. The ion irradiation-induced strain has been explained by Thermal spike and Coulomb explosion model. UV–Vis study showed that the optical band gap reduced from 3.87 to 3.72 eV with increasing the ion fluence which can be ascribed to the formation of intermediate states and free radicals between the valance and band conduction band. Rutherford Backscattering Spectrometry (RBS) ensured that the film thickness decreased from 210 to 183 nm with increasing the ion fluence. The simulation of the RBS spectra provides the elemental composition of Sn (0.37), Ti (0.65) and O (0.85) in SnO2 and TiO2 nanocomposite thin films.

High energy (150 MeV) Fe11+ ion beam induced modifications of physico-chemical and photoluminescence properties of high-k dielectric nanocrystalline zirconium oxide thin films

Abstract This work presents the influence of dominated electronic energy loss over nuclear energy loss induced by swift heavy ion (SHI) irradiation on the physico-chemical, optical and other properties of RF grown zirconium oxide (ZrO2) thin films. For this purpose, thin films of ZrO2 grown on glass substrate were irradiated by 150 MeV Fe11+ ions with a range of fluence from 2E12 to 5E13 ions/cm2 to understand the mechanism of induced modifications and defects generation. The XRD results confirmed that the virgin and irradiated ZrO2 thin films were crystalline in nature with monoclinic and tetragonal structure. The crystallite size varied from 19.93 nm to 46.43 nm with varying ion fluence. Strain, dislocation density and stacking fault were used to investigate the changes in structural parameters. Tauc's plot method was employed for the quantitative evaluation of optical energy band gap (Eg) that exist in the range of 4.45–4.62 eV. The transmittance (%) of the virgin and Fe11+ ions irradiated samples was determined in the range of 35.69–66.09% using UV–Vis. spectroscopy. Further, the refractive index was determined using different methods significantly depends on the optical band gap. The broad PL emission peaks were obtained at 375 nm and 440 nm with the excitation wavelength (λex.) of 300 nm. The variation in PL intensity with increasing ion fluence was attributed to the creation or annihilation of primary or complex defects. FTIR spectroscopy was employed for the analysis of chemical modifications in vibrational bonds of samples and the band obtained 660 cm−1was assigned to the asymmetrically coupled Zr–O–Zr stretching which presents the strong vibration in samples. The band intensity increased up to the fluence 5E12 ions/cm2 and decreased at a higher fluence of 1E13 ions/cm2. Rutherford backscattering spectroscopy technique was used to determine the thickness (165 nm) of the samples.

Ion irradiation (low & high energy ion) induced surface plasmon resonance in Cu(10%)C70 nanocomposite thin films

Cu-C70 nanocomposite thin films were deposited on glass, silicon and TEM grids by thermal co-evaporation; the thin films were irradiated by 350 keV Ar ions and 120 MeV Ag ions at different fluences, ranging from 1 × 1013 to 3 × 1016 ions cm−2 in a high vacuum chamber. Rutherford backscattering (RBS) of pristine film verified that the thickness and copper content of thin films were 30 nm and ∼10 at%, respectively. The modifications in structure and optical properties of irradiated thin films were studied by UV-visible absorption spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS); the results were compared with those of pristine film. Raman spectroscopy gave evidence of transformation of fullerene C70 matrix into amorphous carbon after irradiation by 350 keV Ar ions at a fluence of 3 × 1014 ions cm−2. At 1 × 1015 ions cm−2 fluence, a surface plasmon resonance band due to Cu nanoparticles appeared at ∼627 nm in the visible absorption spectrum. This band was seen to undergo blue shift at higher fluence values. TEM confirmed that increasing fluence brings about the coarsening of Cu nanoparticles (from 2.4 to 6.6 nm). Moreover, XPS study ruled out the possibility of formation of any Cu compound due to irradiation. In contrast, irradiation by 120 MeV Ag ion led to amorphization of Cu (10%) C70 nanocomposite thin films at higher fluences. The SPR band intensity at 627 nm was appreciably enhanced at a fluence of 3 × 1013 ions cm−2. The amorphization of C70 due to irradiation by 120 MeV Ag ion at fluence 3 × 1013 ions cm−2 was confirmed by the appearance of D and G band in the concerned Raman spectra. Moreover, this brings about a small increase in particle size. Both particle coarsening and amorphization of C70 were responsible for the emergence of SPR band due to copper.

Low energy Kr5+ ion beam engineering in the optical, structural, surface morphological and electrical properties of RF sputtered TiO2 thin films

Titanium dioxide (TiO2) thin films were grown on Silicon and glass substrates at room temperature by RF sputtering deposition technique. All deposited thin films were irradiated by 800 keV Kr5+ low energy ion beam with varying ion fluence from 1E15 ions/cm2 to 1E17 ions/cm2. The decreases in crystallite size from 42.09 nm to 27.36 nm (by Scherrer's formula) with increased in ion fluence were observedusing X-ray Diffraction (XRD) technique. The orientation of the different planes was observed but the plane (112) confirmed the preferred orientation as determined by the texture coefficient using XRD patterns. The surface morphology of the samples was studied by Atomic Force Microscopy (AFM) technique in the tapping mode and the Root Mean Square (RMS) roughness (Rq) was found to be increased from 0.739 nm to 3.20 nm with increases the ion fluence. The energy bandgap was found to be increased from 4.06 eV to 4.30 eV by increased in ion fluence due to electron confinement at nano-scale and also observed Urbach energy and optical conductivity by UV–Visible spectroscopy. The Urbach energy of thin films was observed to increased with increasing the ion fluence. The photoluminescence (PL) spectra confirmed the enhancement in the recombination of electron hole pair with increases the oxygen vacancies by increases the ion fluence. The peak at 382 nm was observed at higher fluence of 7E15 ions/cm2, 3E16 ions/cm2 and 1E17 ions/cm2. In the Raman studies, all six Raman modes at their positions for anatase phase of TiO2 thin films were successfully observed. The thickness of thin films was observed 268 nm and elemental composition of titanium and oxygen in all thin films were confirmed in the ratio of 1:2 by using Rutherford Backscattering Spectrometry (RBS). The electrical properties were studied by measuring the variation of current (I) with respect to the applied potential (V) at room temperature and the conductivity of the irradiated thin films was decreased with increases of ion fluence.

Radiative Recombination in the Cu(In,Ga)Se2 Thin Films Irradiated with Hydrogen Ions

The irradiation-induced effects in Cu(In,Ca)Se2 thin films after irradiation with hydrogen ions with dose of [Formula: see text][Formula: see text]cm[Formula: see text] and different energies in the range of 2.5–10[Formula: see text]keV were studied. Irradiated and nonirradiated thin films were investigated by low-temperature (4.2[Formula: see text]K) photoluminescence and photoluminescence excitation methods. The appearance of intense bands at [Formula: see text][Formula: see text]eV and 0.77[Formula: see text]eV in the photoluminescence spectra may be related to radiative recombination on the irradiation-induced defects with deep energy levels in the bandgap of Cu(In,Ca)Se2 solid solutions. A possible nature of these defects and process of radiative recombination are discussed.

Investigation of structural, electrical and optical properties of oxygen (O7+) ion irradiated CdZnO thin films for solar cell applications

An effective method to improve the properties of nano-structured CdZnO thin films for the application in solar cells is demonstrated. CdZnO thin films have been fabricated on glass substrates by direct current (dc) magnetron sputtering and irradiated with high energetic oxygen ions (O7+) of energy 100 MeV of different SHI fluences of 1E+ 11, 5E+ 12 and 1E+ 13 ions/cm2, respectively. Structural properties of the films have been investigated by grazing incidence XRD and reveal hexagonal wurtzite structure oriented along c-axis. The crystallinity of the film enhanced gradually at lower ion fluence (1E+11 ions/cm2) thereafter tending towards polycrystalline nature due to the continuous increase in SHI irradiation fluence. The surface roughness (RMS) decreased (from 19 to 11.24 nm) with SHI irradiation fluence which leads to the polycrystalline nature of the films. Optical properties of the films reveal that the band-gap after irradiation decreased due to enhancement in the transmittance. The electrical resistivity of pristine CdZnO films decreased with ion irradiation from 2.47 to 8.55 × 10–2 Ω-cm. Hall mobility of films increased to 75.4 cm2 V–1 s–1 with SHI-irradiation fluence from 32 cm2 V–1 s–1 (pristine) due to a gradual increase in the concentration of charge carriers and grain boundary scattering with the increased mean free path.

Evolution of SPR in 120 MeV silver ion irradiated Cu (18%) C60 nanocomposites thin films

Copper metal embedded fullerene C60 thin films are deposited on various substrates via resistive heating co evaporation technique. Rutherford back scattering simulated spectrum confirms the thickness and composition of thin film to be ~ 32 nm and ~ 18 at%, respectively. The deposited thin films are irradiated by 120 MeV Ag ion beam for different fluences within the range, from 1 × 1012 to 3 × 1013 ions/cm2. UV–vis absorption spectroscopy study reveals the appearance of surface plasmon resonance (SPR) band in pristine thin film at ~ 622 nm; this phenomenon is ascribed to the presence of copper nanoparticles in C60 matrix. The SPR band intensity increases with rising fluences, which is suggestive of the growth of Cu nanoparticles. Growth of Cu nanoparticles is further confirmed by transmission electron microscopic (TEM) and X-ray diffraction (XRD) study. Whereas the conversion of C60 into amorphous carbon (a-C) is confirmed by Raman spectroscopy, XRD results of pristine Cu–C60 thin film record the presence of Cu2O within the nanocomposite thin film. However, both X-ray photoelectron spectroscopy (XPS) and XRD studies on irradiated thin film samples authenticate the growth of Cu metal nanoparticles with concurrent removal of oxygen.

Electron Beam Irradiated Al Doped ZnO Thin Films as Efficient Tunnel Recombination Junction for Hydrogenated Amorphous Silicon/Cu(In,Ga)Se₂ Tandem Solar Cells.

A tunnel recombination junction (TRJ) layer for hydrogenated amorphous silicon (a-Si:H)/ Cu(In,Ga)Se₂ (CIGS) tandem solar cells is investigated. An Al-doped zinc oxide (AZO) thin film is applied to the TRJ, and the influence of electron beam (e-beam) irradiation on defects along the TRJ is investigated. The AZO thin films are prepared using radio frequency (RF) sputtering and the e-beam is irradiated at 200 W RF power and 2 keV DC power for 5 min. In the e-beam irradiated AZO thin film, the number of oxygen vacancies and Zn interstitials increases, which in turn strengthens the effect of defect-enhanced tunnel recombination.

Effect of high gamma radiations on physical properties of In2S3 thin films grown by chemical bath deposition for buffer layer applications

Abstract Polycrystalline In2S3 thin films have been grown on SnO2/glass substrates by chemical bath deposition technique and irradiated at different high gamma doses 3, 7, 15 and 40 kGy. X-ray diffraction, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Spectrophotometer, Photoluminescence and Thermoluminescence were used to investigate physical properties of In2S3 thin films induced by gamma irradiation. After being irradiated, structural properties of In2S3 thin films have shown that preferred orientation has been moved from (4 0 0) plan at 2θ1 = 33.42° to a new created orientation at 2θ2 = 38.06° for 40 kGy gamma dose. EDS analysis has shown that atomic percentage (S/In) has been strongly varied for 40 kGy which indicate significant changes in stoichiometry. Thermoluminescence of irradiated In2S3 thin films has revealed a good sensitivity toward absorbed gamma dose. After irradiation, optical transmittance of In2S3 thin films has been increased from 50% to a maximum value of 70% in the visible range for 15 kGy dose. Band gap energy Eg has been slightly decreased. Other optical parameters such absorption and extinction coefficients, refractive index and permittivity have been determined. These experimental results show that gamma radiations can be used for tuning physical properties of In2S3 thin films for photovoltaic applications.

Defect-induced photoluminescence from gallium-doped zinc oxide thin films: influence of doping and energetic ion irradiation.

Herein, we present defect-induced photoluminescence behavior of Ga-doped ZnO (GZO) thin films with varying doping (Ga) concentrations and energetic ion irradiation. The Ga-doped ZnO thin films were prepared by a sol-gel spin-coating method. Micro-photoluminescence (μ-PL) was carried out to investigate the defect-related emission with the variation of doping concentration and ion irradiation. The PL spectra revealed that all films showed near-band-edge (NBE) emission along with a broad visible emission band, consisting of violet, blue, green, and yellow emission bands. The intensity of these emission bands was found to be strongly dependent on the Ga doping concentration and ion irradiation. Interestingly, a pronounced violet emission band around 2.99 eV (415 nm) was observed for the Ga-doped ZnO thin films with high Ga doping concentration, whereas an irradiated film with high ion fluence exhibited a strong green emission around 2.39 eV (519 nm); however, we concluded that the violet emission might have originated from zinc interstitial defects (Zni), and the concentration of Zni increased with the increasing doping concentration. The green emission is ascribed to the oxygen vacancies (VO), and the concentration of the VO defects increases with the increasing ion fluence. Thus, the μ-PL spectra of the irradiated films with emission dominating in the blue and green regions could be attributed to the formation of extended defects such as clusters and ionizing centers of Zni and VO. Herein, an in-depth understanding of the variation in defects related to the emission bands from these films is reported and correlated with the transport properties of these films for their possible optoelectronic applications.

Physical properties investigation of samarium doped calcium sulfate thin films under high gamma irradiations for space photovoltaic and dosimetric applications

This research work is dedicated to study structural, morphological, optical and photoluminescence properties of samarium doped calcium sulfate (CaSO4) thin films after exposure to high gamma radiations. Polycrystalline doped CaSO4 thin films have been grown on glass substrates by spray pyrolysis technique and irradiated at different high gamma doses 3, 7, 15 and 40 kGy. Physical characterization of irradiated thin films has been made by X-ray diffraction, Spectrophotometer, Scanning Electron Microscope, Energy Dispersive Spectroscopy, Fluorescence Spectrometer and Thermoluminescence. The most remarkable result, as shown by structural analysis, is the increase of grain size from 52 to a maximum value of 93 nm for 15 kGy gamma dose which indicates a clear enhancement in crystal structure by gamma irradiation. Moreover, the preferred orientation has been immediately changed from (102) plan to (100) just after the first 3 kGy gamma dose. SEM micrographs of irradiated thin layers show deep modifications in surface morphology. Optical transmission spectra have shown a sharp and intense peak at 350 nm wavelength. Band gap energy has been slightly decreased from 3.9 eV before irradiation to 3.6 eV for 40 kGy. A new and strong energy level noted En has been emerged and created due to high gamma irradiations in addition to the principal one relative to band gap energy. Other parameters like absorption and extinction coefficients and refractive index have been determined. Thermoluminescence data show a high sensibility to gamma radiations doses which offer opportunities for dosimetry applications. These experimental results suggest the use of irradiated samarium doped calcium sulfate as optical window for space photovoltaic devices where gamma rays are abundant. These results are also helpful for researchers using CaSO4 thin films near nuclear apparatus (nuclear reactors and particle accelerators) or those interested in studying interaction between radiations and condensed matter.

Effect of gamma irradiation dose on the structure and pH sensitivity of ITO thin films in extended gate field effect transistor

Abstract Even though several studies have demonstrated the use of Indium Tin Oxides (ITO) as an extended gate field effect transistor (EGFET), the effect of different doses of gamma radiation on the intrinsic properties of the ITO films has not been considered. This study investigates the effect of gamma irradiation on the structural, optical, morphological and electrical properties as well as pH sensitivity (as an extended gate field effect transistor) of ITO thin films. ITO thin films with thickness of 400 nm were prepared using a radio frequency sputtering technique. The samples were then subjected to various doses of gamma radiation from a Co-60 radio-isotope (0.5 kGy, 1 kGy, 1.5 kGy, and 2 kGy). The structural and morphological changes as well as transmission and absorption of the thin films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Field-Emission Scanning Electron Microscope (FESEM) and UV–Vis spectrophotometry, before and after irradiation. The irradiated ITO thin films were then used as an extended gate field effect transistor to determine its ability to improve sensitivity as pH sensors. The grain size and transmittance in the range 300–900 nm of the ITO films were found to decrease with increasing gamma irradiation dose. In contrast, the uniformity and surface roughness of ITO thin films increased with increasing gamma radiation dose due to the formation of lattice defects. Moreover, the electrical resistance of the thin films increased with increasing dose because of the low current density and high number of surface defects associated with irradiation. The pH sensitivity of the ITO thin films improved after irradiation, possibly due to the concomitant increase in surface roughness with increasing radiation dose. The improvements in the pH sensitivity of ITO thin films after irradiation justify their potential use as pH sensors.

Charging of electron beam irradiated amorphous carbon thin films at liquid nitrogen temperature

We studied the charging behavior of an amorphous carbon thin film kept at liquid-nitrogen temperature under focused electron-beam irradiation. Negative charging of the thin film is observed. The charging is attributed to a local change in the work function of the thin film induced by electron-stimulated desorption similar to the working principle of the hole free phase plate in its Volta potential implementation at elevated temperature. The negative bias of the irradiated film arises from the electron beam induced desorption of water molecules from the carbon film surface. The lack of positive charging, which is expected for non-conductive materials, is explained by a sufficient electrical conductivity of the carbon thin film even at liquid-nitrogen temperature as proven by multi-probe scanning tunneling microscopy and spectroscopy measurements.

High energy 120 MeV Ti9+ ion beam induced modifications in optical, structural and surface morphological properties of titanium dioxide thin films

Titanium dioxide thin films were deposited by RF Sputtering technique on Silicon (100) and ITO substrates followed by annealing at 500 °C for 6 h. The synthesized samples were irradiated with Ti9+ heavy ions of energy 120 MeV at various fluences. The strain, stress and crystallite size were calculated by analysing the data of X-ray diffraction (XRD) patterns. The increase in crystallite size was observed from XRD analyses. Modifications in the surface morphology, surface roughness, RMS roughness and grain size distribution were investigated using atomic force microscopy (AFM). Variation in optical energy band gap was observed by Tauc's relation, which shows decreasing trend with increases in fluence (3.91 eV–3.58 eV). Urbach energy and extinction coefficient were also determined in Uv–Visible characterization. Raman spectroscopy was used to identify the crystal phases and chemical structure of virgin and irradiated TiO2 thin film samples. The statistics of oxygen bonding to the metal ions and information about phase composition in the material was estimated by the FTIR study. Furthermore, the Rutherford backscattering (RBS) experiment was carried out to confirm the film thickness and presence of Ti in the samples. Herein disorder in the structure has been introduced through irradiation leading to improvement in texturing and crystallization at different irradiation fluence.

Improvement of structural, optical and electrical properties of iron doped indium oxide thin films by high gamma radiations for photocatalysis applications

Iron doped indium oxide (In2O3:Fe) thin films have been deposited on glass substrates by spray pyrolysis technique and irradiated by four high gamma doses 1, 5, 10 and 100 kGy. We have investigated the influence of applied gamma radiations on structural, optical, photoluminescence and electrical properties of In2O3:Fe thin films using X-ray diffraction, Raman spectroscopy, spectrophotometer, Photoluminescence spectrometer and Hall Effect measurements. Structural analysis revealed that preferred orientation (400) plan depicted at 2θ = 35.5° was kept after exposure to gamma radiations with a noticeable improvement of crystallinity for all doses. Average transmission values in the transparent domain [600–2500] nm were increased from 79% to a maximum value of 88% for irradiated thin layer by 10 kGy. Band gap energy was also increased from 3.32 eV to 3.5 eV after irradiation by 10 kGy. Different optical parameters such as refractive index n(λ), extinction coefficient K(λ), lattice dielectric constant (εL), high frequency dielectric constant (ε∞), plasma frequency (ωP) and the ratio of carrier concentration to electron effective mass (Nm*) were determined and analyzed. Single-oscillator Wemple-Didomenico model was applied to calculate the dispersion parameters E0 and Ed after gamma irradiation. Photoluminescence spectra of thin films show an overall decrease in their peak intensities after γ-irradiation. Hall Effect measurements of In2O3:Fe thin films revealed that electrical resistivity have been decreased from 5.07 * 10−2 Ω cm to a minimum value of 1.75 * 10−2 Ω cm at 10 kGy. All these good experimental results can lead to a potential use of gamma irradiated iron doped indium oxide thin film for optoelectronic devices. Photocatalytic activity of γ-irradiated In2O3:Fe thin films to decompose methylene blue were studied under sun light. Optimum irradiated thin film shows an enhancement of photocatalytic activity under sun light with a percentage of dye decolorization equals to 87%.

Linear and nonlinear optical properties of irradiated Toluidine Blue thin films

Homogeneous thin films of Toluidine Blue (TB) are successfully prepared by thermal evaporation technique. Fourier Transform Infrared (FTIR) confirms the high chemical stability of TB films after UV and γ-irradiation. X-ray diffraction (XRD) patterns confirm the polycrystalline phase of the powder form, and as amorphous phase of the thin films. Both of UV and γ-irradiation processes, show a limited effects on the morphology of TB thin films. Dispersion parameters such as dispersion energy, the oscillator energy, the value of the dielectric constant at high frequency, and the ratio of free carriers to the effective mass of charge carrier have been calculated for both pristine and irradiated thin films. The optical absorption spectra of TB thin films reveal three main peaks, in the UV and visible region of spectra, corresponding to n−π∗ and π−π∗ orbital molecular transitions. The onset and optical energy gaps are found to be 1.38 and 2.95 eV for the pristine thin films, respectively. Our results indicate that the irradiation by UV and gamma rays have not affected either the type of transition or the energy gap values. The third order susceptibility (non-linear optical susceptibility χ3, The nonlinear refractive index n2 and the non-linear absorption coefficient βc are calculated.

The variations of hydrophilic self-cleaning properties and refractive index dependence in the ZrO2 thin films by gamma irradiation

ZrO2 thin film samples were produced by the sol-gel dip coating method. Four different absorbed dose levels (such as ~ 0.4, 0.7, 1.2 and 2.7 Gray-Gy) were applied to ZrO2 thin films. Hence the absorbed dose of ZrO2 thin film was examined as physical dose quantity representing the mean energy imparted to the thin film per unit mass by gamma radiation. Modification of the grain size was performed sensitively by the application of the absorbed dose to the ZrO2 thin film.Therefore the grain size reached from ~50 nm to 87 nm at the irradiated ZrO2 thin film. The relationship of the grain size, the contact angle, and the refractive index of the irradiated ZrO2 thin film was investigated as being an important technical concern. The irradiation process was performed in a hot cell by using a certified solid gamma ray source with 0.018021 Ci as an alternative technique to minimize the utilization of extra toxicological chemical solution.Antireflection and hydrophilic properties of the irradiated ZrO2 thin film were slightly improved by the modification of the grain size. The details on the optical and structural properties of the ZrO2 thin film were examined to obtain theoptimum high refractive index, self-cleaning and antireflectiveproperties.

Detailed optical analysis of 100 MeV Ni7+ ion irradiated WO3 thin films using Surface Plasmon Resonance

Modifications in the structural, optical properties and surface morphology of RF sputtered WO3 thin films after irradiation with 100 MeV Ni7+ ions have been reported in the present article. The WO3 thin films were deposited at different sputtering pressures (10–50 mTorr). Despite the grain growth due to irradiation, no structural phase transformation has been observed for the WO3 thin films deposited up to 30 mTorr growth pressure. However, complete amorphization post irradiation was detected for the orthorhombic WO3 thin film grown at 50 mTorr sputtering pressure. AFM images indicated that the pristine WO3 thin film consists of uniform grains having smooth surface morphology. Upon irradiation, grain size increased consistently along with increase in surface roughness (Rq) at all sputtering pressures. The root mean square roughness (Rq) estimated from AFM analysis increased from 1.76 nm in pristine film to 9.89 nm in response to irradiation at a fluence of 1 × 1012 ions cm−2. A systematic decrease in optical band gap has been observed with irradiation, which can be correlated with Ni7+ ion induced mid-gap and near band edge defect states. Surface Plasmon Resonance (SPR) technique has been recognized as an appropriate tool to study the optical properties of pristine and irradiated WO3 thin films. SPR reflectance curves were recorded in angular interrogation mode at 633 nm excitation wavelength for pristine and Ni7+ ions irradiated WO3 films deposited at varying deposition pressure.