Sn-doped Zinc Oxide Research Articles

Unveiling the importance of controllable growth of c-axis oriented Sn-doped ZnO nanorod arrays: towards humidity sensing applications

In this study, tin (Sn)-doped zinc oxide (ZnO) nanorod arrays (SZO) were prepared using a sonication assisted sol-gel immersion method, with the growth of the nanorod arrays controlled by varying the immersion time in the precursor material. Morphology images taken using a Field Emission Scanning Electron Microscope (FESEM) demonstrated an enlargement of the average diameter of the nanorod arrays from 55 nm at 5 min immersion to 122 nm at 200 min immersion. The cross-sectional and surface elemental analysis showed that the sample immersed for 60 min has the highest detection of Sn, with a bulk concentration of 1.8 at.% and surface concentration of 1 at.%. Interestingly, we noticed that Sn is not exist on the surface of 200 min immersion, indicating the depletion of the Sn precursor due to the prolongation of the immersion time. From the current voltage (I-V) analysis, 60 min immersion sample generated the lowest thin film resistivity, which engendered the best humidity sensitivity of 4.05. This study demonstrated the significant importance of optimizing the immersion or growth time for doped 1-D nanostructures to obtain the best humidity sensing performance.

Sn-Doped Zinc Oxide as an Electron Transporting Layer for Enhanced Performance in PbS Quantum Dot Solar Cells.

Colloidal PbS quantum dot solar cells (QDSCs) have been primarily demonstrated in n-i-p structures by incorporating a solution-processed ZnO electron transporting layer (ETL). Nevertheless, the inherent energy barrier for the electron extraction at the ZnO/PbS junction along with the defective nature significantly diminishes the performance of the PbS QDSCs. In this study, by employing Sn-doped ZnO (ZTO) ETL, we have tuned the conduction band offset at the junction from spike-type to cliff-type so that the electron extraction barrier can be eliminated and the overall photovoltaic parameters can be enhanced (open-circuit voltage of 0.7 V, fill factor over 70%, and efficiency of 11.3%) as compared with the counterpart with the undoped ZnO ETL. The X-ray photoelectron spectroscopy (XPS) analysis revealed a mitigation of oxygen vacancies in the ZTO ETL of our PbS QDSCs. Our work signifies the importance of Sn doping into the conventional ZnO ETL for the superior electron extraction in PbS QDSCs.

Control of NLO and photocatalysis properties based on the use of Sn-doped ZnO thin films for optoelectronics applications

Thin films of zinc oxide (ZnO) have unique properties that make them suitable for various applications. In this study, we used a spray pyrolysis process to develop undoped ZnO and ZnO doped with Sn thin films on a glass substrate. We aimed to investigate the effect of Sn concentration on the optical, nonlinear optical, and structural properties of ZnO:Sn thin films. X-ray diffraction analysis revealed that all the deposited ZnO thin films exhibit polycrystalline hexagonal structures well-oriented along the c-axis. The obtained films were transparent in the visible range, with a transmittance between 70% and 80%. The optical energy bandgap values for the films varied from 3.16 eV to 3.29 eV. We also determined the second- and third-order nonlinear susceptibilities, which decreased with increasing Sn concentration. We investigated the photocatalytic activity of the ZnO-doped Sn thin films using methylene blue dye under visible light. Sn doping enhanced the photocatalytic activity of ZnO thin films, with constant rate values of 0.00046 and 0.00074 min[Formula: see text] for ZnO and ZnO:Sn thin films, respectively.

Impact of Sn-doping on the optoelectronic properties of zinc oxide crystal: DFT approach.

This study aims to provide a concise overview of the behavior exhibited by Sn-doped ZnO crystals using a computational technique known as density functional theory (DFT). The influence of Sn doping on the electronic, structural, and optical properties of ZnO have been explored. Specifically, the wavelength dependent refractive index, extinction coefficient, reflectance, and absorption coefficient, along with electronic band gap structure of the Sn doped ZnO has been examined and analyzed. In addition, X-ray diffraction (XRD) patterns have been obtained to investigate the structural characteristics of Sn-doped ZnO crystals with varying concentrations of Sn dopant atoms. The incorporation of tin (Sn) into zinc oxide (ZnO) has been observed to significantly impact the opto-electronic properties of the material. This effect can be attributed to the improved electronic band structure and optical characteristics resulting from the tin doping. Furthermore, the controllable structural and optical characteristics of tin-doped zinc oxide will facilitate the development of various light-sensitive devices. Moreover, the impact of Sn doping on the optoelectronic properties of ZnO is thoroughly investigated and documented.

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.

Influence of Sn doping on the optoelectronic properties of ZnO nanoparticles.

Zinc Oxide (ZnO) nanoparticles (NPs) obtained a lot of attention from researchers and industries because of their superior properties as an optoelectronic material. Doping, especially tin (Sn), can further fine-tune their optoelectronic properties. In this manuscript, we have reported the optoelectronic properties of Sn-doped ZnO NPs, which were synthesized by a simple chemical solution method. A wide range of dopant (Sn) concentrations were used in the ratios of 0, 1, 3, 5, 7, and 10 weight percent. The effects of dopant (Sn) concentration on the structural, morphological, elemental composition, and optical properties of ZnO NPs were investigated by using an X-ray diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM), X-ray photoelectron spectrometer (XPS) and UV-Vis-NIR respectively. XRD analysis revealed the shifting of diffraction patterns towards a higher angle along with decreasing intensity. The calculated crystallite size using the XRD varied from 40.12 nm to 28.15 nm with an increasing doping percentage. Sn doping notably influences the size of ZnO NPs, along with crystal quality, strain, and dislocation density. The X-ray photoelectron spectroscopy (XPS) study showed the presence of zinc (Zn), oxygen (O), and tin (Sn) with their preferred oxidation states in the synthesized NPs. UV-Visible spectroscopy (UV-Vis) showed that the bandgap changed from 3.55 to 3.85 eV with the increasing concentration of Sn. FE-SEM revealed that the structures and surfaces were irregular and not homogeneous. The above findings for ZnO nanostructures show their potential application in optoelectronic devices.

Study on fabrication of Sn-doped ZnO thin films oriented to the application for organic dye degradation catalysts in water environment

In this study, zinc oxide (ZnO) doped with Sn thin films were deposited on the glass substrate at 550 °C by dip-coating technique using the solution synthesized by sol-gel method. The structural, surface morphology, optical and photocatalytic property of thin films were studied. X-ray diffraction (XRD) analysis showed that the Sn-doping greatly changed the microstructure, morphology and optical properties of ZnO films, which may contribute to the enhancement of photocatalytic activity. Additionally, the photocatalytic activity was investigated using methylene blue dye under solar irradiation, with has high UV index from 7 to 8. The results indicated that Sn-doped ZnO had a higher photocatalytic activity and Sn dopant greatly increased the photocatalytic activity of ZnO thin film.

Tuning of zinc oxide temperature sensing and optical absorption properties by tin heavy-doping

This paper presents the feasibility of tin (Sn) heavily doped zinc oxide (ZnO) thin film as an active layer for a microbolometer and the effect of this Sn heavily doping on the structural, optical and electrothermal properties of Sn-doped ZnO (SnxZn1-xO) thin films. The SnxZn1-xO thin films were deposited on substrates using an RF/DC co-sputtering method at room temperature with different Sn dopant concentrations %, x (x = 0.22, 0.26 and 0.32). It was found that the optical and electro-thermal properties were strongly affected by Sn doping. The result revealed an increase in the visible and infrared radiation absorption and electrical conductivity with increasing Sn doping whereas the temperature coefficient of resistance (TCR) decreases. A maximum TCR value of 1.9%/K with a sheet resistance (Rs) of 233 kΩ/□ was observed with 0.22 Sn doping concentration. The result proved that the Sn doping could help to decrease the TCR temperature dependence and the sheet-resistance of ZnO thin film as well as increasing its IR radiation absorption that makes it a strong candidate for the active layer of microbolometer.

ZnO a multifunctional material: Physical properties, spectroscopic ellipsometry and surface examination

The investigation reports on the transparent and conducting pure and metal doped zinc oxide (ZnO) thin layer. The layers are ultrasonic sprayed onto microscope glass substrates at 350 °C. The effect of Sn doping level (from 0% to 3%) is discussed in one hand and metal (Al, Cu and Sn) doping effect on the properties in other hand. Spectroscopic ellipsometry, optical, structural and electrical analyses of the as-grown films have been achieved. The (002)-oriented hexagonal wurtzite crystal structure is revealed by X-ray pattern having a grain size of 4.5–15 nm which confirms the nanosized aspect. The UV–VIS–IR spectrophotometer measurements reveal that the as-grown films are highly transparent in the visible and IR ranges (T~90%). A slight influence of dopants on the band gap energy which ranges between 2.24 and 2.29 eV is emphasized. The electrical parameters such as bulk density, resistivity and mobility are measured by Hall measurement system (HMS). The films thickness is estimated by spectroscopic ellipsometry values and found to be of 178–330 nm. The electrical properties confirm an enhancement of bulk density and conductivity within the range − 1.06 × 1012–5.09 × 1013 (cm−3) and 3.2 × 10−5–1.05 × 10−3(1/Ω cm) due to dopants incorporation as predicted. Inversion to p-type is demonstrated in Sn-doped ZnO sample. The nanostructures are observed in 2D scanned AFM views, size are of micro/nanometer and roughness is of 3.39–15 nm.

Sunlight-driven enhanced photocatalytic activity of bandgap narrowing Sn-doped ZnO nanoparticles.

In this paper, we grab to utilize one of the trending techniques with efficient implications in wastewater treatment of organic pollutants, the photocatalytic degradation method shining out in the research field. Herein, tin (Sn)-doped zinc oxide (ZnO) nanoparticles (NPs) (Sn/ZnO) with different doping concentrations (1, 2, 3, 4, and 5 wt%) were synthesized via a simple co-precipitation assisted method and later subjected for their physico-chemical, morphological, and optical characterization. In addition, photocatalytic activity as the concerned study was investigated as to record the different doping levels of Sn/ZnO to examine the effect of doping concentration in relation with the degradation efficiency. We know that the optical bandgap of pure ZnO was 3.26 eV while it tends to increase slightly upon increasing the doping concentration. In the present investigation, methylene blue (MB) dye was used as a model pollutant to evaluate the photocatalytic activity of Sn/ZnO photocatalysts under natural sunlight. Varied doping concentrations of Sn/ZnO were compared with different characterization techniques while XRD analysis shows up 4-Sn/ZnO with sharp peak at (1 0 1) plane with smaller grain size in comparison to other Sn/ZnO samples. The morphological recognition depicts the hexagonal structure with smaller size for 4-Sn/ZnO which offers more active sites with improved photocatalytic activity, higher surface area for the transportation of pollutants. Fluorescence spectra results revealed that Sn dopant suppresses the charge carrier recombination. The lower intensity of PL indicated reduced recombination rate, which resulted in enhancing the photocatalytic activity. To investigate the possible mechanism, kinetics and reusability studies were performed. The 4% Sn-doped ZnO nanoparticle concentration showed highest photocatalytic activity when compared with other doping levels.

Fabrication of Sn-doped ZnO hexagonal micro discs anchored on rGO for electrochemical detection of anti-androgen drug flutamide in water and biological samples

Prostate cancer is one of the major causes of death around the globe leading to cancer deaths in the US standing at a second position. Flutamide is one of the important drugs which is utilized in clinical diagnosis. Even though over usage and improper discharge leads to very serious harm to both living and environmental bodies. In this aspect developing a sensor for ultra-trace level detection of flutamide is very much indeed with selectivity, stability, and reproducibility. Herein, we report a facile synthesis of hexagonal Sn doped zinc oxide (Sn-ZnO) anchored on reduced graphene oxide (rGO) hybrid nanocomposite in discriminating reduction of flutamide. As per prepared Sn-ZnO/rGO nanocomposite has exhibited good catalytic performance when compared to bare and other modified electrodes. Resulting in inactive sites, large surface areas, synergic effects, and crystalline growths. Noticeable merits include the wide linear range of 0.01 to 170 µM and Limit of detection (LOD) of 7.3 nM with an excellent sensitivity of 14.10 µA µM−1 cm−2 and satisfying stability. The modified electrode was successfully applied as a real-time analysis in both biological and water bodies with promising recoveries.

Development of Sn-doped ZnO based ecofriendly piezoelectric nanogenerator for energy harvesting application

In this work, we have a demonstrated zinc oxide (ZnO) polymer-based ecofriendly piezoelectric nanogenerator (PENG) on a paper substrate for an energy harvesting application. The ZnO thin film is developed on the paper substrate, where different doping concentrations of Sn have been investigated systematically to validate the effect of doping towards enhancing the device performance. The piezoelectric potential of the fabricated device is evaluated by applying three different loads (4 N, 8 N, 22 N), where the source of the corresponding mechanical loads is based on the object of a musical drum stick. The results suggest that the pristine ZnO PENG device can generate a maximum output voltage and current of 2.15 V and 17 nA respectively. Moreover, the ZnO PENG device doped with 2.5% Sn achieved an even higher voltage (4.15 V) and current (36 nA) compared to pristine ZnO devices. In addition, the hydrothermal growth technique used to develop Sn-doped ZnO has the benefits of high scalability and low cost. Hence, the Sn-doped PENG device is a suitable candidate for energy harvesting applications operating in both uniform and non-uniform loading conditions.

The effect of Sn on electrical performance of zinc oxide based thin film transistor

In this study, we have effectively fabricated undoped and Sn-doped zinc oxide thin film transistors (ZTO TFTs) with the back-gate structure on commercially purchased p-type Si with a thermally grown SiO2 layer (thickness = 100 nm). The ZTO TFTs were prepared via low-cost solution based spin coating method. We investigated the structural and morphological properties of thin films and the effect of Sn doping on the electrical performance of ZnO TFTs. It has been found that the electrical parameters of the ZnO based transistors have highly affected by Sn doping. The field-effect mobility and on/off ratio of doped TFT increased ~ 40 and 106 times by comparison with undoped TFT, respectively. The best results were obtained from 10% Sn doped ZTO TFT with 3.83 cm2 V−1 s−1 the field effect mobility (µsat), 1 V/dec subthreshold slope (SS), 9 V threshold voltage (Vth), 3 × 108 Ion/Ioff ratio and a high on-current of 1.3 mA.

Effect of Sn doping on structural, mechanical, optical and electrical properties of ZnO nanoarrays prepared by sol-gel and hydrothermal process

Undoped and Sn doped Zinc oxide nanorods were prepared by two step process: initially growth of seed layers by sol-gel spin coating technique and then zinc oxide nanorods by hydrothermal process using the precursors zinc nitrate hexahydrate, hexamine and tin chloride. The effects on the electrical, optical, mechanical and structural properties for various Sn concentrations were studied. The crystalline phase determination from X-ray diffraction (XRD) confirms that Sn doped ZnO nanorods have hexagonal wurtzite structure. The variations of stress and strain with different doping concentration of Sn in ZnO nanorods were studied. The doping effect on electrical properties and optical bandgap is estimated by current voltage characteristics and absorbance spectra respectively. The surface morphology was studied with field emission scanning electron microscope (FESEM), which shows that the formation of hexagonal nanorods arrays with increasing Sn concentration. The calculated value of Young's modulus of elasticity (Y) for all the samples remains same. These results can be used in optoelectronic devices.

Optical and Electrical Properties of Sn-Doped Zinc Oxide Single Crystals

Sn dopant in ZnO may significantly improve the n-type conductivity of ZnO through a characteristic double effect. However, studies on bulk Sn-doped ZnO are rare, and the effect of Sn doping on the optoelectronic properties of bulk ZnO is not well understood. In this work, the effect of Sn doping on the optical and electrical properties of ZnO bulk single crystals was investigated through optical absorption spectroscopy, Hall-effect measurements, and thermoluminescence (TL) spectroscopy. Undoped and Sn-doped ZnO single crystals were grown by chemical vapor transport method and characterized by x-ray diffraction analysis. The Sn doping level in the crystals was evaluated by inductively coupled plasma mass spectroscopy measurements. Hall-effect measurements revealed an increase in conductivity and carrier concentration with increasing Sn doping, while TL measurements identified a few donor species in the crystals with donor ionization energy ranging from 35 meV to 118 meV. Increasing Sn doping was also associated with a color change of single crystals from colorless to dark blue.

A Fast Responsive Ultraviolet Sensor from mSILAR-Processed Sn-ZnO

Microwave-assisted successive ionic layer adsorption and reaction was employed to synthesize Sn-ZnO (tin-doped zinc oxide), and its sensitivity to ultraviolet radiation is compared with zinc oxide (ZnO). The sensing films were made by the dip-coated method on an indium titanium oxide glass substrate, and the sensing performance was monitored using the 300–700 nm wavelength of UV–Vis light. Excellent sensitivity and recovery were observed for the Sn-doped ZnO sensor device, especially at 380 nm wavelength of ultraviolet (UV) light (response and recovery time 2.26 s and 8.63 s, respectively, at 5 V bias voltage). The variation in photocurrent with respect to dark and light illumination atmosphere was well illustrated based on the Schottky and inter-particle network effects. Doping of Sn on ZnO nanoparticles varied the surface roughness and crystallite size as observed from scanning electron microscopic and x-ray diffraction studies. Here, we demonstrate a simple and economical fabrication technique for designing a high-performance UV light sensor. The developed device works at room temperature with high durability and stability.

Morphology dependent UV photoresponse of Sn-doped ZnO microstructures

In this work, the UV sensing properties of Sn-doped and/or alloyed zinc oxide (ZnO) microstructures with different morphologies were investigated in order to elaborate the high performance UV photodetectors. We have compared two types of morphologies, i.e. Sn-doped ZnO films (ZnO:Sn) and ZnO microtetrapod (T) networks alloyed- and doped-with Sn (ZnO-T:Sn). The UV response (IUV/Idark) of ZnO:Sn is about 103 and 102 for 0.1 and 0.4 at% Sn, respectively. The three-dimensional highly porous ZnO-T:Sn networks demonstrated higher UV response (by two orders of magnitude) and much faster recovery for detection of UV light, which were attributed to the domination of fast processes such as modulation of potential barriers formed at the interface of the tetrapod arms, which are less dependent on adsorbed species. Thus, the UV response for devices with a distance between the pads (interelectrode distance) of about 60, 400, 800 and 1500 μm is 1.7 × 105, 2.4 × 104, 6.7 × 103 and 925, respectively. All samples demonstrated a sharp increase in photocurrent under illumination with UV light, as well as a fast recovery to the initial electrical baseline. Also, the influence of relative humidity on the rapidity of photodetectors based on ZnO:Sn films and ZnO-T:Sn networks was investigated, confirming a low impact on the rapidity of ZnO-T:Sn networks, with good repeatability and stable electrical baseline, which is very important for effective applications.

Effect of lithium on linear and nonlinear optical properties of Sn-doped zinc oxide prepared by spray pyrolysis

Li and Sn codoped ZnO (LTZO) thin films have been successfully deposited on heated glass substrates at 450°C using the spray pyrolysis technique, the effect of lithium of Sn-doped zinc oxide on the structural, morphological, optical and nonlinear optical properties was investigated using X-ray diffraction, transmission, the RMS average surface roughness, and third harmonic generation (THG). The value of optical band gap Eg was found to be decreased from 3.24 eV to 3.16 eV when the concentration of Li from 0 to 7%, while the concentration of Sn is fixed at 2%.The doping of ZnO films improves the nonlinear response and the highest susceptibility value χ (3) =13.422 × 10-12 (esu) is found at concentration of lithium 7%.

Fabrication of hierarchical Sn-doped ZnO nanorod arrays through sonicated sol−gel immersion for room temperature, resistive-type humidity sensor applications

Hierarchical tin (Sn)-doped zinc-oxide (ZnO) nanorod arrays (SZO) were deposited onto Al-doped ZnO-coated glass substrate by using a sonicated sol–gel immersion method for resistive-type humidity sensor applications. X-ray diffraction patterns revealed that the deposited SZO arrays exhibit a wurtzite structure. SZO possessed smaller average diameter, crystallite size, and thickness than the undoped sample did. The SZO film also exhibited compressive strain and tensile stress values of −0.033% and 77MPa, respectively. Our result showed the sensitivity of the SZO based-sensor improved compared with that of the undoped ZnO, with values of 3.41 and 1.41 at 40% to 70% RH and 70% to 90% RH, respectively. The response and recovery times of the SZO based humidity sensor improved to 230 and 30s, respectively. All these results indicated that SZO had high potential for humidity-sensor applications.

Sn‐doped ZnO thin‐film transistors with AZO, TZO and Al heterojunction source/drain contacts

Bottom gate, top contact thin-film transistors (TFTs) with transparent Sn-doped zinc oxide as the active layer have been fabricated on glass substrate at room temperature. Indium tin oxide, alumni zinc oxide (AZO) and Al thin films serve as the source/drain (S/D) electrode. It turns out that devices with AZO S/D electrodes exhibit preferable properties such as a saturation mobility of 13.6 cm2/Vs, a subthreshold slope of 381 mV/decade, a Vth of 3.47 V and an on/off current ratio of 3.1 × 107. Moreover, the superior output characteristic and lower parasitic resistance demonstrate the excellent contact performance of the tin-zinc oxide TFTs with AZO S/D electrodes.