Sn Doped ZnO Thin Films Research Articles

ZnO/ITO, Sn and Cu Doped ZnO/ITO Films as an Photoanode for Solar Cell: Production and Characterizations

Undoped ZnO and Sn- and Cu-doped ZnO thin films were fabricated on ITO substrates via the SILAR method for this study. The films were then subjected to structural, surface, optical, and electrical characterization. The undoped ZnO thin films displayed a spherical surface morphology, while the Sn-doped ZnO thin films exhibited a nano-flower surface morphology. On the other hand, the Cu-doped ZnO thin films demonstrated a relatively thicker and flat layer, as well as a fractured surface morphology that resulted in voids. The level of crystallization and transmittance values augmented upon doping. With Cu doping, n-p heterojunction structure was obtained from ZnO/ITO films. Hence, it is inferred that the generated Cu doped ZnO/ITO films can serve as alternative transparent conductive films (TCO) due to their low resistivity.

Effect of tin concentrations on the elemental and optical properties of zinc oxide thin films

Pure zinc oxide and Sn-doped ZnO thin films were deposited on a pre-heated glass substrate from tin (II) chloride dihydrate (SnCl2.2H2O) and zinc acetate (Zn(CH3COO))2 precursors using spray pyrolysis technique. The doped films were achieved by adding various quantities of (SnCl2. 2H2O) precursor to the solution of zinc acetate in volume percent range of 0–10. Rutherford Backscattering Spectrometry (RBS) was used to characterise the prepared films to determine their thickness and elemental composition. To examine the films' optical characteristics, a UV spectrometer operating at room temperature and covering a wavelength range of 300–1100 nm was employed. The film's thickness and composition show that as the volume of Sn in the thin films increases, so does the film's thickness. With average transmittance values up to 70 %, all the films are quite transparent in the visible region of the electromagnetic spectrum and have a significant UV cut-off at roughly 380 nm. The reflectivity of Sn-doped ZnO films is seen to be independent of the volume of Sn in the films, and the reflectivity of the films diminishes as the wavelength increases. Sn-doped ZnO thin film has an optical band gap of 3.14–3.18 eV. The properties of the thin film produced make it suitable for solar energy collection and improve the efficiency of solar energy system, various optoelectronics devices and sensor.

Optical and structural properties of Sn doped ZnO thin films synthesized by spray pyrolysis

Optical and structural properties of Sn doped ZnO thin films synthesized by spray pyrolysis

Structural, morphological and optical properties of Sn doped zinc oxide thin films synthesis by sol-gel method for photocatalytic applications

Undoped and tin (Sn)-doped ZnO thin films were synthesized via sol-gel technique and deposited onto the glass substrates using the spin-coating technique. The impact of Sn incorporation at various concentrations on the structural, morphological, and optical properties of ZnO films was studied x-ray diffraction revealed a hexagonal crystal structure for all samples with a preferential crystalline orientation along the (002) plane. The transparency of Sn-doped ZnO thin film in the visible region significantly increased from 75% to 90%. The morphological analysis revealed a decrease in the grain size from 21 nm to 15 nm with Sn content in the matrix of ZnO. The optical properties reveal the contribution of the Burstein-Moss effect and electron-impurity scattering to slightly widen the bandgap from 3.22 eV to 3.24 eV. Urbach energy values demonstrated that the presence of Sn dopant increased the tail-band width of the localized states. These observations suggest that the deposited Sn-ZnO thin films could have possible applications as a photocatalyst for methylene blue (MB) dye degradation.

Structural and photoelectric properties of Sn-doped ZnO thin film with the co-sputtering method

Sn-doped ZnO thin films have been prepared with magnetron co-sputtering. The results indicate that this method can improve the micro-structure of films and enhance its photoelectric performance. The structure and surface morphology results indicate that all the doped films show the preferred orientation (0 0 2), the roughness can decrease to 1.81 nm at 15 W with increasing DC power, the carrier concentration, resistivity decreases, and mobility can reach 7.99×1019 cm−3, 1.27×10−4 Ω·cm and 1047.5 cm2/Vs, respectively, and the observed optical band gap can increase to increase to 3.85 eV.

A low cost Sn doped ZnO thin film based Schottky diode for UV detection

In this paper thin films of Sn doped ZnO was prepared via low-cost chemical sol-gel spin coating process. The Ohmic electrode Aluminum (Al) and Schottky electrode Palladium (Pd) on doped ZnO thin film were deposited through a hard mask by thermal evaporation techniques to obtain a planner Metal-Semiconductor-Metal (MSM) structure; hence present device was horizontal. The electrical characterization is used to analyze the UV detection capability of the fabricated device, and various calculated parameters include saturation current = 8.31 × 10−7 A/cm−2, ideality factor = 4.02, barrier height = 0.75 eV, etc. It was observed that forward and reversed bias current increases when exposed to Ultraviolet (UV) light. In addition, responsivity and series resistance are also reported in this paper.

Structural properties of pure and Sn doped ZnO thin film prepared using sol-gel method

In this work, the pure ZnO and Sn doped ZnO thin films with different volume ratios (2, 4, 6, and 8V/V) of tin chloride have been successfully prepared by using sol-gel method. The structural properties were investigated by using X-ray diffraction (XRD), Scanning electron microscope (SEM), and Atomic force microscope (AFM). The results showed that, pure ZnO and Sn doped ZnO thin films have polycrystalline in nature with hexagonal structure. The structure have different plane at (1 1 1),(0 0 2),(1 0 1),(1 0 2),(1 1 0),(1 0 3),(1 1 2) belong to 2θ of 31.64, 34.30,36.13, 47.43, 56.49, 62.73, 67.83 respectively. The orientation of (002) at 2θ = 34.30 has a narrow FWHM, low strain, and crystalline size equal to 4.913, 3.683, 3.686, 2.455, and4.911 respectively for pure, Sn doped ZnO. Particle shapes were spherical granules morphology for all samples. The AFM images showed that the size of the grains on the surface of thin films increases with the increase in the concentration of impurity which agreement with the SEM results.

Optical Properties of Sn Doped ZnO Thin Film Prepared Using Sol-Gel Method for Optical Limiting Application

In this work, pure Zinc oxide and tin doped Zinc oxide thin films nanoparticles with various volume concentrations of 2, 4, 6, and 8V/V% were prepared by using the sol-gel method. The optical properties were investigated by using UV-Visible spectroscope, and the value exhibits the direct allowed transition. The average of transmittance was around ~(17-23) %in visible region. The optical energy band gap was calculated with wavelength (300-900) nm for pure ZnO and Sn doped ZnO thin films which decreases with increasing concentration from 3.4 eV to 3.1 eV respectively and red shift. The real dielectric(εr) and the imaginary dielectric εiare the same behavior of the refractive index(n) the extinction coefficient (k) respectively. The optical limiting properties were studied by using an SDL laser with a wavelength of 235 nm. ZnO and doping thin films an found efficient as optic limiting and depend on the concentration of the all samples.

Dominance of c-axis orientation on the carrier transport properties of Sn doped ZnO thin films

Sol-gel derived pure and Tin (Sn) doped ZnO thin films were deposited on the glass substrate by cost-effective spin-coating method. The influence of Sn incorporation on the structural, morphological, optical, and electrical properties of ZnO films was investigated by varying Sn concentration. X-ray diffraction reveals the hexagonal crystal structure with a preferential orientation of the crystallites along c-axis in ZnO film after doping with Sn. The transparency of ZnO thin film in the visible region is increased significantly from 72% to 93% after Sn incorporation into the ZnO matrix. The grain size of the film decreased from 27 nm to 20 nm after doping with Sn. The widening of optical band gap from 3.23 to 3.29 eV i.e., a blue shift of absorption edge with Sn doping is attributed to a combination of the Burstein-Moss effect and electron-impurity scattering. Urbach energy values have shown that Sn dopant decreases the width of the band tail of localized states. The electrical properties of the films revealed the decrement of the conductivity in the doped film. The decrement in the conductivity upon Sn doping is explained considering the grain-boundary conduction model and piezoelectric scattering mechanism. The Figure of Merit was calculated to assess the efficiency of the prepared film and was found that the film Sn: ZnO (3 at.%) shows the highest value. The obtained results confirm that Sn dopant has considerable effects on the properties of ZnO thin films and can be used as promising transparent conducting oxide films for optoelectronic applications.

Sn doped ZnO thin films as high resistivity window layer for Cu(In,Ga)Se2 solar cells

For high efficiency Cu(In,Ga)Se2 (CIGS) solar cell, the high-resistivity layer with high optical transmittance has to be adopted between the buffer layer and the high-conductivity window layer. In this paper, we propose Sn doped ZnO (ZTO) film, instead of the traditional intrinsic ZnO (i-ZnO) film, as an alternative n-type high-resistivity window layer for CIGS solar cell. In this experiment, both ZTO and i-ZnO films are strong (002) oriented, and the surface morphologies of the two films are almost the same. The statistical roughnesses of i-ZnO film and ZTO film are 0.58 nm and 0.63 nm, respectively. However, the optical transmittance of ZTO film is higher than that of i-ZnO film with the same thickness. The efficiency of ZTO based CIGS cell was 14.24%, which is almost the same as the efficiency of i-ZnO based CIGS cell. These results fully suggest that it is very feasible to replace i-ZnO with ZTO as the high resistant window layer.

Formaldehyde detection using Sn doped ZnO thin film

This work presents an approach for formaldehyde detection using Sn doped ZnO thin film. The concentration of Sn dopant varies at 0.5at%, 1.0at% and 1.5at%. XRD results show that the thin film possessed a crystallite structure with the highest peak at 002. The crystallite size of undoped, 0.5at%, 1.0at% and 1.5at% Sn doped ZnO thin film are 10.09 nm, 33.36 nm, 8.736 nm and 9.31 nm, respectively. Surface roughness obtained from AFM was 16.9 nm, 10.19 nm, 5.48 nm and 8.57 nm for undoped 0.5at%, 1.0at% and 1.5at% Sn doped ZnO thin film, respectively. The optimal sensitivity is acquired when 1.0at% Sn doped ZnO thin film is used for the detection of 3.4 ppb formaldehyde, where the sensing performance is 92%; while the sensing performance of undoped thin film is only 50%. The response time for undoped and 1.0at% Sn doped ZnO thin film is 10-8 s and 4-10 s, while the recovery time is 38-207 s and 15-34 s, respectively. The 1.0at% Sn doped ZnO thin film also demonstrates a good response in formaldehyde sensing, which was measured for nine consecutive days, where the sensing performance was over 90%.

Influence of Sn dopant on ZnO Thin Film for Formaldehyde Detection

In this work, structural, morphological, electrical and gas sensing of ZnO and Sn doped ZnO thin film at different atomic percentage (0.5at%, 1.0at% and 1.5at%) had been studied. The precursor was prepared by sol-gel method and deposited on an IDE glass substrate by using spin coating technique. The effects of the dopant was then characterized through XRD, AFM, SEM and Agilent LCR Meter. Based on the XRD results, it was found that all films showed the highest diffraction peak intensity at (002) with crystallite size in the range of 8-33nm. Meanwhile the morphological properties from AFM and SEM showed an improvement in surface roughness from 16.7nm to 5.48nm and decrease the grain size from 45.42nm to 40.99nm in the presence of Sn dopant. Based on the image, the grains were uniformly distributed and ZnO thin film showed the hexagonal wurtzite structure, which proved the XRD result. Among all the samples, 1.0at% Sn doped showed the best result for detection of formaldehyde at 0.6ppm which up to 96% compare to undoped, 26.04% at 150°C. The response and recovery time was between 4-16 seconds. This showed that the presence of Sn can help to improve the conductivity of the ZnO thin film.

Effects of Sn Incorporation in ZnO Thin Films on Properties of Perovskite Solar Cells

Properties of electron transporting layer (ETL) play an important role on photovoltaic performances of perovskite solar cells. In this work, effects of Sn incorporation on properties of ZnO-based perovskite solar cells were investigated. Sn-doped ZnO (TZO) thin film as ETL was prepared via a sol–gel method. With 5% atom doping, TZO film coated on an indium doped tin oxide (ITO) substrate provided comparable light transmittance with that of an undoped ZnO/ITO substrate. It was also found that the optical band gap of TZO film (3.30 eV) is slightly wider than that of the ZnO one (3.28 eV). These results suggest that Sn atoms probably incorporated into the ZnO crystal during the sol-gel method. The grains size of perovskite layer coated on TZO or ZnO films also showed variation. The perovskite crystal on the TZO thin film (average 300 nm) was larger than that of the one on ZnO thin film (average 277 nm). The preliminary results indicate that the perovskite solar cell based on TZO film provided higher power conversion efficiency (PCE) of 4.42 % than the ZnO-based device (3.16%). Short-circuit current density (Jsc), open-circuit voltage (Voc) and fill factor (FF) of TZO-based device were also higher than the ZnO-based device. This may be because TZO film may provide lower resistivity and better ETL/perovskite interface contact, confirmed by lower series resistance and higher shunt resistance of the TZO-based device. Finally, this work introduced a simple method to prepare TZO film at low temperature for photovoltaic application. It may help guide the development of flexible solar cells and other optoelectronic devices.

The morphological evolution of ZnO thin films by Sn ions doping and its influence on the surface energy and photocatalytic activity

Abstract In this work, Sn-doped ZnO thin films were deposited by sol-gel method. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, fluorescence spectroscopy, respectively. The composition of the films was examined by energy dispersive X-ray spectroscopy (EDX). The photocatalytic performance was tested using methylene blue (MB) as a simulated organic pollutant. The results showed that all the ZnO thin films were preferentially oriented along the c-axis direction. The Sn-doping led the grains of the ZnO films to decrease. However, a kind of truncated-cone shaped nanostructures occurred on the surface of ZnO thin films when Sn-doping concentration was above 2 at.%, and both the number and the size of the ZnO truncated-cones increased with the further rise of the Sn-doping concentration. As a result, the surface roughness of the films was largely enhanced and the optical absorption was also improved. The wettability of the films was investigated by the water droplet spreading on the ZnO thin film surfaces. It showed that Sn-doping resulted in a smaller contact angle. The photocatalytic test on MB dyes showed that Sn-doping enhanced photodegradation efficiency of ZnO thin films. The improvement of the degradation efficiency was attributed to three main factors: (1) the formation of truncated-cone nanostructures on the surface of ZnO thin films increased the surface roughness and optical absorption; (2) the recombination of photogenerated electrons and hole was suppressed; (3) Sn-doping enhanced the surface energy of the ZnO thin films.

Sn doped ZnO thin film deposition using thermionic vacuum arc technique

Sn doped ZnO thin films were prepared on glass, polyethylene terephthalate (PET) and silicon substrate make use of the thermionic vacuum arc technique and their structural, morphological, optical properties were investigated with various methods. The surface and microstructural properties of the Sn doped ZnO thin films were investigated by X-ray diffractometer, field emission scanning electron microscopy, atomic force microscopy, UV–visible spectroscopy, and Raman spectroscopy. According to the obtained results, all deposited films are in polycrystalline form with large crystallites. Due to larger crystallites on a deposited layer on glass and Si substrates, resistivity was found lower than deposited layer on PET substrate.

Doping and annealing effects on structural, electrical and optical properties of tin-doped zinc-oxide thin films

In this study, Sn doped ZnO thin films at different Sn content (of 0.5%–3.0%) were successfully deposited on soda-lime glass substrates using RF/DC magnetron sputtering technique. The effects of doping concentration and annealing on structural, electrical, and optical properties of Sn doped ZnO thin films were determined in detail. XRD measurements not only revealed the deterioration of crystallinity but also a gradual shift of main peak position to higher values following the doping process. Following the annealing process at different temperatures (150, 250 and 500 °C) a drastic improvement in crystallinity of both doped and undoped ZnO films was observed. AFM measurements have shown that there is a significant modification in surface morphology following the doping process. The mulberry-like structures, for instance, were observed for the 3.0% Sn doped ZnO film. The average transmittance in the visible range was found to be around 90% for all the Sn-doped films after annealing at 500 °C. From the transmission and reflection measurements the band gap energies were calculated, which exhibited a decreasing trend with the increasing Sn content. The observed red-shift in band gap from 3.26 to 3.15 eV was attributed to the band gap shrinkage due to the generation of deep levels in the forbidden band gap following the doping process. It was also revealed that there was an increase in band gap with increase of annealing temperature. The lowest resistivity (9.8 × 10−3 Ω cm) measured at room temperature was recorded for the 1.5% Sn-doped ZnO thin film after annealing at 250 °C.

Modulation of structural properties of Sn doped ZnO for UV photoconductors

Sn doped ZnO thin films are synthesized in order to introduce excess charge carriers depending on various doping densities which modifies the surface, particle size and planar orientation of ZnO crystals. From the view of change in optical properties it is observed that with increasing Sn content, the increase in bandgap takes place which results into improved photo response as compared to pure ZnO. A highly-textured orientation in (002) direction has been observed with the relative increase in lattice parameters. Depending on Sn doping, photoconductor performance has been examined and an optimum Sn wt.% doping level is investigated to achieve maximum photo response in terms of sensitivity, ON/OFF ratio, spectral responsivity and detectivity. The maximum ON/OFF ratio and sensitivity are obtained to be 1.2×105 and 1.0×105 for 7 wt.% Sn doped ZnO sample. Similarly, the highest detectivity and spectral responsivity is obtained to be 1.7×1010 Jones and 1.56 A/W for 7 wt.% Sn-ZnO metal-semiconductor-metal photoconductor respectively.

Optical and electrical properties of Sn-doped ZnO thin films studied via spectroscopic ellipsometry and hall effect measurements

We investigated the optical and the electrical properties of Sn-doped ZnO thin films grown via RF co-sputtering deposition methods at room temperature. Through annealing, the carrier concentrations and mobilities were improved. The ellipsometric angles, Ψ and Δ, of the ZnO:Sn thin films were measured via spectroscopic ellipsometry. Dielectric functions were obtained from the ellipsometric angles by using the Drude and the parametric optical constant models. With an increase in the Sn doping concentration, the Drude model amplitude increased substantially. The Urbach and the optical gap energies of the ZnO:Sn films were determined using the dielectric functions. The carrier concentrations and the mobilities of the ZnO:Sn thin films were measured using Hall-effect measurements. The effective mass of ZnO:Sn was estimated to be 0.274m0, assuming that the carrier concentrations measured via ellipsometry and Hall-effect measurements were the same. A shift in the optical gap energy of the Sn-doped ZnO was found to be due to a combination of the Burstein-Moss effect, electron-electron interactions, and electron-impurity scattering. The discrepancy between the measured and the calculated shifts in the optical gap energy is attributed to Sn-alloying effects.

Sn doping effects on properties of ZnO thin films deposited by RF magnetron sputtering using a powder target

In the present study, tin doped ZnO thin films (ZnO:Sn) at different contents (0–3 wt%) were deposited onto glass substrates by RF magnetron sputtering using a powder compacted target at room temperature. The effect of Sn concentration on the structural, optical and electrical properties of the ZnO:Sn thin films were investigated. The X-ray diffraction analysis shows that the pure ZnO thin film exhibits a strong intensity of the (002) peak indicating a preferential orientation along the c-axis. For Sn doped ZnO thin films, there is a change in the orientation from the (002) plane to the (101) one. The undoped ZnO thin films have transmittance 85% in the visible range and slightly increased for 0.5 wt% of Sn, while it get decreased with further increasing the Sn doping concentration. The optical band gap energy get increased with increasing the doping concentration. Moreover, the electrical conductivity and conduction mechanism are also studied by impedance spectroscopy in the frequency range of 1KHz–13 MHz at various temperatures (633–743 K). The AC conductivity in ZnO thin films increased with angular frequency. The frequency exponent S decreases with increasing temperature. Such behavior suggests that the correlated barrier hopping (CBH) model may be suitable to explain the conduction mechanism in ZnO thin films. The activation energy values calculated from angular frequency and DC conductivity are in good agreement confirming that the conduction mechanism is thermally activated by hopping between localized states.

Sn-doped ZnO nanocrystalline thin films with enhanced linear and nonlinear optical properties for optoelectronic applications

In the current work, nanocrystalline undoped and Sn doped ZnO thin films with different doping concentrations (1, 3, 5, 7at%) have been deposited on glass substrate by low cost spin coating technique. The strong effect of Sn doping on structural, morphological, optical, nonlinear properties have been observed. X-ray diffraction study revealed that all the thin films are preferentially grown along (002) plane. The crystallite size is found to be increased with increasing the concentration of Sn, similar behavior was observed by atomic force microscopy analysis. Optical study shows that the prepared thin films are highly transparent. The direct optical band gap was calculate and found to be 3.16, 3.20, 3.22, 3.34, 3.18eV for pure and doped films respectively. The refractive index, linear susceptibility, nonlinear absorption coefficient, nonlinear susceptibility and nonlinear refractive index were calculated. Furthermore, the third order nonlinear optical properties are investigated using Z-scan technique and their values are found to be −3.75×10−8cm2/W, −3.76×10−3cm/W and 0.65×10−3esu for 7% Sn doped ZnO, respectively. There is a good correlation between theoretical and experimental third order nonlinear properties and higher values shows that the deposited films are may be applied in nonlinear optical applications.