Search

In this work, Chromium (Cr) doped Zinc Oxide (ZnO) nano-structured thin films were deposited using ultrasonic spray pyrolysis technique on glass substrate at different concentration (0,1,3,5,10 wt%) with a substrate temperature of 350oC. The effect of chromium on zinc oxide thin films was studied to extract the structural, optical and electrical characteristics using XRD, UV-Vis spectroscopy and Hall effect measurement instruments respectively. The work on undoped ZnO showed hexagonal wurtzite structure, with an ideal orientation of (101). The increase in strain with respect to doping concentration confirmed decrease in the crystallite size. Variation in the surface roughness on doping Cr is observed. The optical results depicted influence of Cr doping resulted in the decrease in transmittance. Band-gap (BG) obtained using Tauc's plot was seen to vary with Cr-doping. Hall effect measurement at standard conditions observed decreases in carrier concentration, and indicating the conduction to be n-type. The study of third-order nonlinear optical characteristics, such as susceptibility χ(3), nonlinear refractive index (NRI) (푛2), and nonlinear absorption coefficient (β) was carried out. These findings suggest that the films consist of self-defocusing nonlinearity. The overall results confirmed that the structural and optical results were dependent on Cr concentration in ZnO. [ABSTRACT FROM AUTHOR]

A polycrystalline nanostructured thin film of zinc cadmium sulfide was meticulously fabricated on a glass substrate using the thermal evaporation method physical vapor deposition within a vacuum chamber. Different doping concentrations were introduced by varying the cadmium (Cd) content, resulting in Zn1- x Cd x S films with Cd concentrations ranging from x = 0.00–0.20 wt %. The impact of Cd doping on the third-order nonlinear optical (TONLO) properties of these films was thoroughly studied using the Z -scan method, employing a diode-pumped solid-state continuous-wave laser. To gain insight into the structural characteristics, the Zn1- x Cd x S thin films underwent analysis through x-ray diffraction. Optical studies confirmed the tunability of the optical band gap (Eg) in the Zn1- x Cd x S films, ranging from 3.88 eV for undoped ZnS to 2.80 eV for the film fabricated with 20 wt. % of Cd-content. This significant reduction in 'Eg' renders the films highly suitable for use as absorbing layers in applications such as solar cells and optoelectronics. Surface morphology analysis, performed via field emission scanning electron microscopy, revealed noticeable alterations with increased Cd doping. Significantly, the doped films exhibited a substantial redshift in the band edge and an increase in transmittance within the visible and near-infrared regions. The investigation of TONLO properties, including the nonlinear absorption coefficient (β), nonlinear refractive index (n 2) and susceptibility χ (3), yielded values ranging from 3.15 × 10−3 to 8.16 × 10−3 (cm W−1), 1.65 × 10−8 to 7.45 x 10–8 (cm2 W−1), and 3.12 × 10−5 to 7.86 × 10−5 (esu), respectively. These results indicate the presence of self-defocusing nonlinearity in the films. Overall, the outcomes underscore the potential of Cd-doped ZnS nanostructures in modifying surface morphology and enhancing NLO characteristics. Zn1- x Cd x S thin films exhibit promise for applications in nonlinear optical devices, as evidenced by these encouraging findings. [ABSTRACT FROM AUTHOR]

The present work reports the study on effect of annealing at different temperature and dissimilar Cd/Zn ratios on optical linear and nonlinear properties of Cd1-xZnxS (in x ratios of = 0.00, 0.01, 0.03, 0.05 and 0.1 wt. % of Zn) thin films deposited by spray pyrolysis (SP) technique. All the fabricated films are polycrystalline in nature and having a hexagonal crystal structure with the single phase of CdS was confirmed by Powder X-ray diffraction studies (P-XRD). The Scherer rule was used to assess the size of the crystallite and was found to be increasing with increasing annealing temperature. FESEM images display uniform grains and decrease marginally with an increase in doping content and annealing. The optical energy band gap (Eg) of the prepared films ranged from 2.40 eV to 2.64 eV. The laser-induced damage threshold (LDT) value of the annealed Cd1-xZnxS thin film is 0.1520 KW/cm2. The NLO parameters of the prepared samples were calculated at 532 nm from the Z-scan data under solid state continuous wave laser irradiation and the 3rd-order NLO components such as β, n 2 and χ(3) were found to be enhanced with the annealing temperature i.e. from 1.58 × 10−5 to 4.85 × 10−3 (cmW−1), 1.08 × 10−8 to 4.38 × 10−8 (cm2W−1) and 7.22 × 10−7 to 5.94 × 10−6 (esu) respectively. These favourable results of NLO parameters suggests, the current fabricated nanstructured films are capable material for photonic device applications. [ABSTRACT FROM AUTHOR]

In this article, the authors are presented the work on the evaluation of structural and third-order nonlinear optical (NLO) properties of lead (Pb)-doped zinc oxide (ZnO) thin films. The nano structured Zn1-xPbxO thin films were lay down on the glass substrate at an heating temperature of 350 °C with different Pb-doping concentration ('x' ratios of 0, 0.01, 0.05 and 0.1 wt. % of Pb) using the standard spray pyrolysis technique. The powder X-ray diffraction (P-XRD) spectroscopic analysis reveals the polycrystalline existence in the lead doped thin films in evidence with the hexagonal structure. The reformed grain sizes with enhanced doping content was perceived through surface morphological analysis with the help of field emission scanning electron microscopy and are in line with the X-Ray diffraction observations. The upgraded optical band gaps (Eg) were inferred through UV–Vis spectroscopic studies for the tailored films from 3.21 eV (pure ZnO) to 3.34 eV (10 wt. % of Pb). The defect states appearances and photoluminescence properties are discussed for the fabricated thin films using the resulted room temperature photoluminescence (RTPL) spectroscopic data. The third-order NLO parameters were calculated by potentially exposing the prepared thin films to the z-scan analysis under a continuous wave solid state laser at an excitation wavelength of 532 nm. The reverse saturable absorption, excited state absorption and self-defocusing effects were observed from the z-scan test along with the elevated nonlinear absorption coefficient (β) from 4.74 × 10–4 to 1.05 × 10–3 (cm/W) and negative nonlinear refractive index (n 2 ) from 1.42 × 10–8 to 5.60 × 10–8 (cm2W−1). In addition to this, the third-order NLO susceptibility (χ (3)) values are also calculated and are augmented from 0.82 × 10–5 to 1.45 × 10–4 (esu). An optical limiting (OL) topography with the limiting thresholds was also explored at the experimental wavelength. Hence, the outcome of structural, linear and nonlinear optical studies acknowledged the ability of the Zn1-xPbxO thin films in the field of optoelectronic device applications. [ABSTRACT FROM AUTHOR]

The work presented here reported the thickness dependent structural, linear and nonlinear optical properties of nanostructured Cd1−xZnxO thin films. Thin films were prepared with two different thickness (≈ 0.5 µm and 1 µm) by employing a spray pyrolysis (SP) technique for different Zn-doping levels (Cd1−xZnxO with the x value of 0.00, 0.01, 0.05 and 0.1). X-ray diffraction studies confirm the polycrystalline nature having a cubic crystal structure. In terms of an aspect ratio of the columnar structure and dispersion in hexagonal (1 1 1) basal plane orientation, a thickness dependency of structural evolution was discussed. The Scherrer rule was employed to determine the crystallite size and found to be decreased. FESEM images indicate grains which are uniform and grain size slightly increased with an increase in dopant concentration, annealing and thickness of the films, respectively. The optical energy band gap (Eg) of the prepared films was found to be increased from 2.50 to 2.67 eV. The NLO parameters of the samples were measured from the Z-scan data under DPSS continuous wave laser excitation at 532 nm and the results reveal that reverse saturable absorption (RSA) and self-defocusing natures are the attributed and observed nonlinearity of the nanostructures. The third-order NLO components such as β, n 2 and χ(3) are found to be enhanced with one order of magnitude higher with the influence of thickness from 1.25 × 10–4 to 2.47 × 10–3 (cm W−1), 7.08 × 10–9 to 3.35 × 10–8 (cm2 W−1) and 4.06 × 10–7 to 1.96 × 10–6 (esu) respectively. The inspiring results of NLO parameters are also due to the increasing localized defect states on grain boundaries as the film thickness increases, suggesting the prepared films are a promising material for nonlinear photonic device applications. [ABSTRACT FROM AUTHOR]