SnO2 Semiconductor Research Articles

The hinge morphology of SnO2 as multifunctional semiconductor: What we can learn from simulations, theory, and experiments

Our interaction with materials occurs through their surfaces whose properties are strongly dependent on morphology, structure, and atomic arrangement. Unfortunately, obtaining a detailed correlation between the surface morphology with its properties is not straightforward. SnO2 is a multifunctional semiconductor ceramic that is exploited in several technological devices from sensor to energy storage, water splitting, and solar to fuel photocatalysis. This work focused on the structural, energetic, and electronic properties of low and high index surfaces of SnO2 semiconductor and assessed the morphology-dependent process via first-principles calculations, at the density functional theory level. Importantly, our explicitly dynamic approach elucidates the atomic arrangements and stability of the exposed surfaces to provide a close match between experimental field emission scanning electron microscopy images and computational simulation. These findings can potentially set a foundation for establishing synthesis techniques for drive the morphology evolution through the control of temperature/pressure, and/or based on surface interactions of the selective adsorption of solvents/surfactants.

Schottky barrier modulation of bottom contact SnO2 thin-film transistors via chloride-based combustion synthesis

The enhanced carrier flow at the interface between Au and SnO2 semiconductors, which initially form Schottky contacts, is realized using chloride-based combustion synthesis. Chloride-based combustion systems can achieve chlorine (Cl) doping effects as well as conversion to crystalline SnO2 films at clearly lower temperatures (∼250 °C) than conventional precursors. Due to the Cl doping effect, the high carrier concentration can induce thin potential barriers at the metal/semiconductor (MS) junctions, resulting in carrier injection by tunneling. As a result, compared to conventional SnO2 thin-film transistors, the devices fabricated by combustion synthesis exhibit significantly improved electrical performance with field-effect mobility of 6.52 cm2/Vs (∼13 times), subthreshold swing of 0.74 V/dec, and on/off ratio of ∼107 below 300 °C. Furthermore, because of the enhanced tunneling carriers induced by the narrowed barrier width, the Schottky barriers are significantly reduced from 0.83 to 0.29 eV (65% decrease) at 250 °C and from 0.42 to 0.17 eV (60% decrease) at 400 °C. Therefore, chloride-based combustion synthesis can contribute to developing SnO2-based electronics and flexible devices by achieving both high-quality oxide films and improved current flow at the MS interface with low-temperature annealing.

Surface Engineering in SnO2/Si for High-Performance Broadband Photodetectors

Silicon-based photodetectors are important optoelectronic devices in many fields. Many investigations have been conducted to improve the performance of silicon-based photodetectors, such as spectral responsivity and sensitivity in the ultraviolet band. In this study, we combine the surface structure engineering of silicon with wide-bandgap semiconductor SnO2 films to realize textured Si-based heterojunction photodetectors. The obtained SnO2/T-Si photodetectors exhibit high responsivity ranging from ultraviolet to near-infrared light. Under a bias voltage of 1 V, SnO2/T-Si photodetectors (PDs) with an inverted pyramid texture show the best performance, and the typical responsivities to ultraviolet, visible, and near-infrared light are 0.512, 0.538, 1.88 (800 nm, 67.7 μW/cm2) A/W@1 V, respectively. The photodetectors exhibit short rise and decay times of 18.07 and 29.16 ms, respectively. Our results demonstrate that SnO2/T-Si can serve as a high-performance broadband photodetector.

First-principles investigation on structural and optoelectronic properties of buckled SnO monolayer for effective solar energy scavenging

Two-dimensional (2D) materials have gathered considerable attention for next-generation optoelectronic devices owing to their intriguing optical and electronic properties. The semiconductor SnO has shown potential for flexible electronics, optoelectronics, gas sensing, and Li-ion battery applications due to its indirect bandgap, and high carrier mobility. In the present work, we investigate the physical properties of a buckled tin oxide (SnO) monolayer using density functional theory (DFT) calculations. The structural analysis reveals that buckled SnO monolayer is energetically stable and exhibits the hexagonal crystal structure. Phonon dispersion analysis depicts the dynamical stability of the buckled SnO monolayer and obtained the quadratic behavior of flexural acoustic modes (ZA) near the zone center. Further, the electronic property calculation shows that the buckled SnO is an indirect semiconductor with a bandgap of 1.71 eV and the transparent behavior of the material is disclosed by analyzing the optical parameters. Moreover, the computed solar power conversion efficiency of 16.76% for buckled SnO monolayer demonstrates the potential as a light absorber in the field of solar energy scavenging.

A Study of the Optical and Structural Properties of SnO2 Nanoparticles Synthesized with Tilia cordata Applied in Methylene Blue Degradation

Water contamination is one of the most worrisome problems in the world. Industrial dyes are discharged without previous treatment, promoting water pollution and affecting the environment. In this paper, semiconductor SnO2 nanoparticles (NPs) were synthesized using Tilia cordata extract, as a reducing agent, at different concentrations, 1%, 2%, and 4% (weight/volume; w/v). These NPs were used as photocatalysts characterize an alternative for degrading wastewater compounds. Nanoparticle symmetry is an important factor for understanding the properties that provide tools for further treatments. Additionally, the structural, morphological, and optical properties of the green-synthesized SnO2 NPs were studied. Fourier transform infrared spectroscopy (FTIR) showed the characteristic absorption band of Sn–O centered at 609 cm−1. Meanwhile, X-ray diffraction (XRD) confirmed a tetragonal rutile-type crystalline phase without impurities whose crystallite size increased from 15.96 nm and 16.38 nm to 21.51 nm for SnO2-1%, SnO2-2%, and SnO2-4%, respectively, as extract concentration was increased. NPs with a quasi-spherical morphology with agglomerations were observed through scanning electron microscopy (SEM). On the other hand, the bandgap remained at ~3.6 eV throughout all samples, even at variable extract concentrations. The NPs yielded great photocatalytic activity capable of degrading methylene blue (MB) dye under ultraviolet radiation and solar radiation, achieving degradation percentages of 90% and 83% of MB under UV and solar radiation at 90 and 180 min, respectively.

Inducing the SnO2-based electron transport layer into NiFe LDH/NF as efficient catalyst for OER and methanol oxidation reaction

• Introduce the electron transport layer SnO 2 between NiFe LDH and conductive substrate NF was first reported. • SnO 2 nanosheets are interwoven to form a sponge-like 3D structure, which promotes the formation of relatively smaller and thinner NiFe LDH nanosheets, thereby generating more active sites and reducing electron transmission resistance. • It was verified that the electronic structure of Ni and Fe was optimizing via the introduction of SnO 2 . • NiFe LDH@SnO 2 /NF possesses a low overpotential of 234 mV at 10 mA cm −2 for OER and 1.396 V at 10 mA cm −2 for methanol oxidation reaction. In an electrocatalyst with a heterointerface structure, the different interfaces can efficiently adjust the catalyst's conductivity and electron arrangement, thereby enhancing the activity of the electrocatalyst. Ultrathin and smaller NiFe LDH was successfully constructed on the surface of SnO 2 nanosheet supported NF by layer by layer assembly, and exhibits lower overpotential of 234 mV at a current density of 10 mA cm −2 , which only increases by 6.4% even at a high current density of 100 mA cm −2 . The excellent OER activity of catalyst is attributed to the contribution of the semiconductor SnO 2 electron transport layer. Through experiments and characterization, 3d structure SnO 2 nanosheets control the growth of ultra-thin nickel-iron, the hierarchical interface between SnO 2 and NiFe LDH can change the electron arrangement around the iron and nickel active centers at the interface, resulting the valence states of iron slightly increased and Ni 3+ content increased. The result will promote the oxidation of water. Meanwhile, the SnO 2 semiconductor as electron transport layer is conducive to trapping electrons generated in oxidation reaction, promoting electrons transferring from the NiFe LDH active center to the Ni substrate more quickly, and enhance the activity of NiFe LDH. It also shows excellent activity in an electrolyte solution containing 0.5 M methanol and 1 M KOH, and only 1.396 V (vs. RHE) is required to drive a current density of 10 mA cm −2 .

An overview of SnO2 based Z scheme heterojuctions: Fabrication, mechanism and advanced photocatalytic applications

Not just people, but all living species, desire a clean and green environment to live a happy and healthy life. However, in our ever-increasingly congested world, it is quite challenging. Excessive deforestation, factory smoke, various chemical compounds, agricultural chemicals, etc. all pollute our environment severely. Some of its adverse consequences include water contamination and a shortage of energy supplies. In recent times, photocatalysts have sparked tremendous attention as a means of addressing energy demands as well as environmental challenges (water pollution). For this, SnO2 and SnO2 based photocatalysts have gained a great attention due to its good photocatalytic ability. In the same way, SnO2-based Z-scheme photocatalysts has extended significant interest to address these concerns due to its strong photocatalytic characteristics, energy savings, eco-friendliness, and lack of adverse health effects. Though, the photocatalytic effectiveness of conventional SnO2 semiconductors, with their shortcomings, falls well short of the real requirements. The current review emphasizes on admirable properties and several synthesis processes of SnO2 which make it an ideal photocatalyst. This study also stresses the fundamental shortcomings of SnO2 that restrict its utilization. The central section of this review is concentrated on SnO2-based Z-scheme photocatalysts and most recent significant research modification of Z-scheme SnO2-based photocatalysts. The photocatalytic applications of Z-scheme SnO2-based photocatalysts for pollutants removal, energy conversion, and water splitting are also summarized. In conclusion, we have addressed the challenges and future exploration of SnO2-based photocatalysts with a Z-scheme heterojunction type for pollutant degradation and energy conversion.

Comparative Study of SnO2 and ZnO Semiconductor Nanoparticles (Synthesized Using Randia echinocarpa) in the Photocatalytic Degradation of Organic Dyes

Symmetry in nanomaterials is essential to know the behavior of their properties. In the present research, the photocatalytic properties of SnO2 and ZnO nanoparticles were compared for the degradation of the cationic dyes Methylene Blue (MB) and Rhodamine B (RB). The nanoparticles were obtained through a green synthesis process assisted by Randia echinocarpa extracts; they were then analyzed through Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) to characterize their structure. Transmission electron microscopy (TEM) was used to identify the morphology and disclose nanoparticle size, and the optical properties were studied through Ultraviolet–visible spectroscopy (UV–Vis). The results show that the synthesized SnO2 and ZnO nanomaterials have quasispherical morphologies with average sizes of 8–12 and 4–6 nm, cassiterite and wurtzite crystal phases, and band gap values of 3.5 and 3.8 eV, respectively. The photocatalytic activity yielded 100% degradation of the MB and RB dyes in 210 and 150 min, respectively. ZnO performed higher photocatalytic degradation of the cationic dyes than SnO2 due to a higher content of Randia echinocarpa extracts remaining after the green synthesis process.

Effects of NiO, SnO2, and Ni-doped SnO2 semiconductor metal oxides on the oxygen sensing capacity of H2TPP

Improving the performance of optical oxygen sensors can be accomplished by adding metal oxide semiconductors (MOSs) additives to the composition comprising an oxygen-sensing agent immobilized in a polymeric thin film. For several decades, MOSs have attracted great interest in gas sensors due to their high sensitivity to many target gasses. Herein, meso-tetraphenylporphyrin (H2TPP) dye was immobilized into the poly(1-trimethylsilyl-1-propyne) (poly(TMSP)) silicone rubber in the presence of NiO, SnO2, Ni:SnO2 metal oxide particles as additives, and their thin films were prepared to investigate oxygen-sensitive optical chemical sensor properties. The characterizations of the synthesized metal oxide powders were carried out through XPS, XRD, FT-IR, PL spectroscopy and SEM methods. Intensity-based spectra and decay kinetics of H2TPP-based thin films were investigated for the concentration range of 0%–100% [O2]. The oxygen sensitivity (I0/I100) of the porphyrin was calculated as 70%. Whereas the relative signal intensity values of H2TPP-based sensor slides were measured as 75%, 80%, and 88% in the presence of NiO, SnO2, Ni:SnO2 additives, respectively. The H2TPP in combination with Ni:SnO2 semiconductor provided a higher I0/I100 value, larger response range, higher Stern-Volmer constant (KSV) value, and faster response time compared to the undoped form, and also NiO and SnO2 additive-doped forms of H2TPP. The response and the recovery times of the porphyrin-based sensing slide along with Ni:SnO2 additives have been measured as 12 and 50 s. These results make the H2TPP along with the MOSs promising candidates as oxygen probes.

Group theoretical methods in solid state Physics of SnO2

Oxide semiconductor SnO2 shows excellent photoelectronic properties and sensitivities of gases. It is known that their special properties are originated by a stable large band-gap. In nano-SnO2, the above properties have been extensively explored, and nano-SnO2 will find wide applications in microelectronics, photoelectronics, sensor and compound function ceramics. According to our study using group theory, a single SnO2 crystal with rutile-type structure shows four Raman active modes, A 1g, B 1g, B 2g and E g. The additional A 2μ and E μ modes correspond to transverse-optical (TO) and longitudinal-optical (LO) vibrations. Moreover, we applied application of perturbation theory, consequently, the spectrum of commercial SnO2 sample showed the Raman bands in accordance with the theory.

Innovation of Tin Oxide Ceramic Manufacturing Process Based on WSN and Remote Visualization Technology.

A wireless sensor network (WSN) collects information from small sensors, processes the information effectively through a built-in computing system, forms a dynamic network topology in a self-organizing method, and sends it to the base station through wireless communication. At the same time, the scale of data generated by high-performance scientific computing has rapidly increased from GB and TB to EB. The traditional scientific vision postprocessing model that initially saved the data and then performed the vision processing became a very time-consuming and troublesome process due to the limitation of disk I/O efficiency, which seriously affected the development of technology, and the accuracy was relatively low. The development of high-performance computer parallel processing technology has promoted parallel visualization, and the expansion of Internet bandwidth has accelerated remote visualization. SnO2, or tin oxide, is a kind of N-type semiconductor material with a rutile structure. The crystal structure is stable, the corrosion resistance is good, the melting point is high, the resistance after doping is low, and the sinterability is good. Materials that are sensitive to optics, electrodes, and gases have a wide range of uses. This paper proposes a new data fusion algorithm based on BP neural network and studies the key technologies for the design and implementation of a web-based multiuser remote interactive vision system. In this paper, the effects of ZnO, MnO2, Nb2O5, CuO, and Li2CO3 doping on the conductivity and bulk density of SnO2 semiconductor ceramics were studied by means of ceramic preparation method, using intelligent resistance meter, bulk density tester, X-ray diffractometer, and scanning electron microscope, thus promoting the innovation of tin oxide ceramic preparation process.

SnO/β-Ga2O3 heterojunction field-effect transistors and vertical p–n diodes

In this work, we report on the realization of SnO/β-Ga2O3 heterojunction vertical diodes and lateral field-effect transistors for power electronic applications. The p-type semiconductor SnO is grown by plasma-assisted molecular beam epitaxy on n-type (100) β-Ga2O3 with donor concentrations of 3 × 1017 cm−3 for the diode devices and 8.1 × 1017 cm−3 for the field-effect transistors. The deposited films show a predominant SnO (001) phase featuring a hole concentration and a mobility of 7.2 × 1018 cm−3 and 1.5 cm2/V s, respectively. The subsequent electrical characterization of the heterojunction diodes and field-effect transistors show stable switching properties with on/off current ratios >106 and specific on-resistances below 4 mΩ cm2. Furthermore, breakdown measurements in air of the non-field-plated heterojunction transistor with a gate-to-drain distance of 4 μm yield a breakdown voltage of 750 V, which equals an average breakdown strength of nearly 1.9 MV/cm. The resulting power figure of merit is calculated to 178 MW/cm2 demonstrating state-of-the-art properties. This emphasizes the high potential of this heterojunction approach.

Visible light stimulated binary nanostructure and defect enriched TiO2-SnO2 for photocatalysis and antibacterial activity

This work brings the two large band gap semiconductors TiO2 and SnO2 into composite catalyst for the visible light photodegradation of methyl orange (MO) dye. In this scenario, different ratios of TiO2-SnO2 nanocomposites were synthesized via sol-gel and precipitation methods. The variable compositions (TS 5% and TS 10%) are applied for the photocatalytic studies to destroy MO dye. Moreover, to the best of our knowledge for the first time, TiO2-SnO2 was focused against staphylococcus aureus bacterium.

Distinction of gaseous mixtures based on different cyclic temperature modulations

The dynamic nonlinear response of a SnO2 semiconductor gas sensor under two types of temperature modulations was investigated to enhance the selectivity of the sensor for gaseous mixtures. A “rapid increase and slow decrease” and “slow increase and rapid decrease” in temperature scan were periodically applied to the SnO2 semiconductor gas sensor. The resultant dynamic change in the conductance of the sensor was characteristically changed depending on the gases and the combination of the mixture. The gaseous mixtures were partly possible to distinguish by the three types of classification based on the sum of the individual sensor responses and the selective response to a specific gas.

Room-Temperature Synthesis of [BMIm][Sn5O2Cl7] with ∞1(Sn2OCl2) Strands in a Saline [BMIm][SnCl3] Matrix.

The novel tin(II) oxychloride [BMIm][Sn5O2Cl7] (BMIm = 1-butyl-3-methylimidazolium) is obtained by the room-temperature reaction (25 °C) of black SnO and SnCl2 in [BMIm]Cl/SnCl2 as an ionic liquid. The title compound can be described as composed of noncharged, infinite ∞1(Sn2OCl2) strands that are embedded in a saline matrix of [BMIm]+ and [SnCl3]-. The ∞1(Sn2OCl2) strands consist of a backbone of edge-sharing OSn4/2 tetrahedra, which represent one-dimensional (1D) strands cut out of the layer-type structure of SnO. In [BMIm][Sn5O2Cl7], the ∞1(Sn2OCl2) strands, which mimic a 1D semiconductor, are terminated by chlorine atoms, whereas they are interconnected by oxygen atoms in the 2D semiconductor SnO. The view of the noncharged ∞1(Sn2OCl2) strands in a saline [BMIm][SnCl3] matrix is validated by dissolution experiments. Thus, electron microscopy and Raman spectroscopy show a deconstruction of [BMIm][Sn5O2Cl7] single crystals after treatment with chloroform with a dissolution of [BMIm][SnCl3], the formation of SnCl2 needles, and tin oxide as a solid remain.

A compendium and meta-analysis of flatband potentials for TiO2, ZnO, and SnO2 semiconductors in aqueous media

Semiconductor/electrolyte interfaces are of great interest to numerous scientific fields including renewable energy, (photo)electrochemistry, and energy storage. The semiconductor flatband potential is a key parameter in locating the conduction band minimum or valence band maximum of the semiconductor material in electrolyte. Despite its importance for quantifying the energetic location of the semiconductor bands, literature reports for the same material demonstrate significant variability in the flatband potential. In this compendium and meta-analysis, reported flatband potentials of the common semiconductor materials TiO2, SnO2, and ZnO in aqueous electrolyte were compiled and assessed to quantify the spread in literature flatband potentials as well as determine the factors that lead to the significant spread. For TiO2, SnO2, and ZnO, literature flatband potentials referenced to the reversible hydrogen electrode span a range of nearly 2 V each. Flatband potential tabulations were separated by variables such as the solution pH, the crystalline polymorph, the crystal facet, the morphology, and the dimensions or combinations of these variables to assess the factors that contribute to the observed spread. Important and surprising findings from these categorizations are summarized: (1) Even for the narrowest categorizations, the spread in flatband potential is still large. (2) Flatband potentials of TiO2 and SnO2 follow the expected Nernstian dependence with solution pH. ZnO materials deviate from this Nernstian dependence. (3) In the aggregate, there is no statistically significant difference in the reported flatband potentials of anatase and rutile TiO2. Single crystal tabulations were the only distributions to have statistically significant differences in the flatband potential between anatase and rutile TiO2. (4) Anatase TiO2 materials with a nanotube morphology appear to have a +400 mV difference in mean flatband potential compared to all other morphologies, but we argue that this is likely due to widespread misuse of the Mott–Schottky analysis. Other interesting findings are revealed within the spread of literature flatband potentials, and possible explanations are provided to generate discussion. We also briefly review and discuss common techniques that were used to determine the flatband potential and the pitfalls/criticisms of these techniques. Last, we discuss some ways in which future research on the determination of the flatband potential can be performed to improve the reliability of reported values and the quality of the work. In total, the results from this meta-analysis suggest multiple factors can affect the measured flatband potential and that an abundance of caution should be applied when attempting to quantify the flatband potential of complex or nanostructured systems.

Annealing Effect on Nanocrystalline SnO2 Thin Films Prepared by Spray Pyrolysis Technique

In recent years, a transparent conducting oxide (TCO) SnO2 semiconductor have gained considerable attention due to their potential application in gas sensors. More number of studies on TCO oxide have focused on the semiconducting metal oxides in which an intensive argument is that the transparent semiconductors. The SnO2 thin films were deposited at 400 °C and then annealed at 500 °C and 600 °C and its structural, optical and electrical properties were characterized. The doping stoichiometric ratio was maintained as 4% and the resulting solution was sprayed on glass substrate which was kept at nozzle distance of 25 cm and the spray rate was 10 mL/min. The prepared pure SnO2 thin films have been characterized by different methods such as XRD, FESEM, UV-Vis NIR and EDAX analyses. It was found that the nanocrystalline SnO2 grains possesses structural features of the tetragonal rutile structure. Hence the prepared thin films are justified to be nanocrystalline and also the mean crystalline size decreased with respect to annealing temperature.

Ag Continuous Doped SnO2 Sensor Selective to Co2 in Presence of Ethanol at Room Temperature

Abstract This paper contains experimental research to minimize the basic limits of the SnO2 semiconductor oxide gas sensor. The operating temperature is high. In addition, their selectivity diminishes with gasses having the same chemical behavior. An experimental methodology is presented to overcome the difficulties of these metal oxides. The efficiency of the gas sensors made of Ag continuously doped at room temperature is excellent. At the end of the testing processes and security measures supplied, laboratory tests and experiments will be conducted to guarantee the acceptability of the planned study.

Artificial photosynthesis: photoanodes based on polyquinoid dyes onto mesoporous tin oxide surface

Dye-sensitized photoelectrochemical cells represent an appealing solution for artificial photosynthesis, aimed at the conversion of solar light into fuels or commodity chemicals. Extensive efforts have been directed towards the development of photoelectrodes combining semiconductor materials and organic dyes; the use of molecular components allows to tune the absorption and redox properties of the material. Recently, we have reported the use of a class of pentacyclic quinoid organic dyes (KuQuinone) chemisorbed onto semiconducting tin oxide as photoanodes for water oxidation. In this work, we investigate the effect of the SnO2 semiconductor thickness and morphology and of the dye-anchoring group on the photoelectrochemical performance of the electrodes. The optimized materials are mesoporous SnO2 layers with 2.5 μm film thickness combined with a KuQuinone dye with a 3-carboxylpropyl-anchoring chain: these electrodes achieve light-harvesting efficiency of 93% at the maximum absorption wavelength of 533 nm, and photocurrent density J up to 350 μA/cm2 in the photoelectrochemical oxidation of ascorbate, although with a limited incident photon-to-current efficiency of 0.075%. Calculations based on the density functional theory (DFT) support the role of the reduced species of the KuQuinone dye via a proton-coupled electron transfer as the competent species involved in the electron transfer to the tin oxide semiconductor. Finally, a preliminary investigation of the photoelectrodes towards benzyl alcohol oxidation is presented, achieving photocurrent density up to 90 μA/cm2 in acetonitrile in the presence of N-hydroxysuccinimide and pyridine as redox mediator and base, respectively. These results support the possibility of using molecular-based materials in synthetic photoelectrochemistry.Graphic abstract

Improved Negative Bias Stress Stability of Sol–Gel-Processed Li-Doped SnO2 Thin-Film Transistors

In this study, sol–gel-processed Li-doped SnO2-based thin-film transistors (TFTs) were fabricated on SiO2/p+ Si substrates. The influence of Li dopant (wt%) on the structural, chemical, optical, and electrical characteristics was investigated. By adding 0.5 wt% Li dopant, the oxygen vacancy formation process was successfully suppressed. Its smaller ionic size and strong bonding strength made it possible for Li to work as an oxygen vacancy suppressor. The fabricated TFTs consisting of 0.5 wt% Li-doped SnO2 semiconductor films delivered the field-effect mobility in a 2.0 cm2/Vs saturation regime and Ion/Ioff value of 1 × 108 and showed enhancement mode operation. The decreased oxygen vacancy inside SnO2 TFTs with 0.5 wt% Li dopant improved the negative bias stability of TFTs.