Tin Doping Research Articles

Electrical characterization of Si-doped n-type α-Ga2O3 on sapphire substrates

ABSTRACTIssues on tin (Sn) doping in the mist chemical vapor deposition of α-Ga2O3 was attributed to conversion of ionization states of Sn from Sn4+ to Sn2+ and/or out-diffusion of Sn after thermal annealing, resulting in highly resistive films. Silicon (Si) doping, instead, was succeeded by the use of a novel doping source of chloro-(3-cyanopropyl)-dimethylsilane [ClSi(CH3)2((CH2)2CN)]. Si was uniformly incorporated in the α-Ga2O3 films and the electrical properties were stable even after the thermal annealing. The activation ratio as donors was nearly 100%. The carrier (electron) concentration was controlled to the level of 1018 cm-3 by the [Si]/[Ga] ratio in the source solution. The maximum mobility was 31.5 cm2/V⋅s, in contrast to 24 cm2/V⋅s with Sn doping, suggesting advantage of Si doping . However, the reduction in dislocation defects in the α-Ga2O3 films formed owing to heteroepitaxy on sapphire was suggested to be the important subject to be considered in the next stage.

Defect formation in In2O3and SnO2: a new atomistic approach based on accurate lattice energies

A new consistent interatomic force field for In2O3and SnO2.

Electrical, dielectric and magnetic properties of Sn-doped hematite (α-SnxFe2-xO3) nanoplates synthesized by microwave-assisted method

Hematite nanoparticles are of interest due to their exceptional electrical and magnetic behavior and various technological applications. The doping of hematite can vary its electrical and magnetic properties. Here, we report the effect of different concentrations of Tin doping on electrical, dielectric and magnetic properties of hematite synthesized by the microwave-assisted method. Tin-doped α- Fe2O3 (α-SnxFe2-xO3) samples have been characterized using XRD, TGA, FESEM, and EDS (mapping). XRD pattern shows the rhombohedral structure of α-SnxFe2-xO3. The synthesized samples have nanoplate like structure with a uniform distribution of tin throughout the sample. Electrical properties were investigated using dielectric and impedance studies. The dc resistivity and ac conductivity decreased with increase in concentration up to x = 0.06 (Sn0.06Fe1.94O3). However, it increased with further increase in the concentration of tin. The hopping of electrons between Fe3+ and Fe2+ in octahedral sites accounts for the observed conduction behavior. A single semi-circle of the cole-cole plot for α-SnxFe2-xO3 indicates the dominant grain boundary effect in conduction. Dielectric constant and loss factor reveal the dielectric relaxation in α-SnxFe2-xO3 samples. The magnetic properties were studied using VSM, which shows that α-SnxFe2-xO3 are antiferromagnetic/weakly ferromagnetic in nature with high coercivity.

Structure, phase transition behavior, and electrical properties of Pb0.99(SnxZr0.95−xTi0.05)0.98Nb0.02O3 ceramics

Pb0.99(SnxZr0.95−xTi0.05)0.98Nb0.02O3 (PNZST(x), 0.10 ≤ x ≤ 0.18) ceramics were fabricated by conventional solid state reaction method. Effects of tin (Sn) doping and its content x on their structure, phase transition behavior, and electrical properties were investigated. Analysis of X-ray diffraction patterns and Rietveld refinement results confirmed the crystal structures of different phases and also compositional driven phase transitions. The results indicated that with the increase in the value of x, orthorhombic phase was transformed into distorted tetragonal phase through rhombohedral phase. Ceramics exhibited the orthorhombic–rhombohedral phase coexistence for 0.10 ≤ x ≤ 0.16, and orthorhombic–rhombohedral–distorted tetragonal multiphase coexistence for x = 0.18. Although the orthorhombic antiferroelectric (AFE) phase was the major phase, no double hysteresis loops were detected through electrical hysteresis loop measurements because the electric field-induced AFE to ferroelectric (FE) phase transition occurred under the applied electric field, and the induced FE phase could not reverse back to AFE state after the removal of electric field. However, the trace of AFE behavior could be observed at a lower testing electric field. Moreover, increasing Sn content led to linear increment in phase transition temperature of FERL-FERH, up to 98.7 °C for x = 0.18.

Phase Segregation Behavior of Two-Dimensional Transition Metal Dichalcogenide Binary Alloys Induced by Dissimilar Substitution

Transition metal dichalcogenide (TMD) alloys form a broad class of two-dimensional (2D) layered materials with tunable bandgaps leading to interesting optoelectronic applications. In the bottom-up approach of building these atomically thin materials, atomic doping plays a crucial role. Here we demonstrate a single step CVD (chemical vapor deposition) growth procedure for obtaining binary alloys and heterostructures by tuning atomic composition. We show that a minute doping of tin during the growth phase of the Mo1–xWxS2 alloy system leads to formation of lateral and vertical heterostructure growth. High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) imaging and density functional theory (DFT) calculations also support the modified stacking and growth mechanism due to the nonisomorphous Sn substitution. Our experiments demonstrate the possibility of growing heterostructures of TMD alloys whose spectral responses can be desirably tuned for various optoelectronic applications.

Stabilising Oxide Core—Platinum Shell Catalysts for the Oxygen Reduction Reaction

Thin film planar models of core-shell catalysts for the oxygen reduction reaction in PEM fuel cells, have been synthesised with tin doped titania as the support for platinum. High-throughput methods have been used to investigate the effect that the level of tin doping in the titania core supporting material and the degree of crystallisation have on the loading of platinum at which bulk platinum like oxygen reduction behaviour is achieved. At high effective coverages of platinum, the oxygen reduction activity is always similar to that of a polycrystalline platinum electrode. This suggests that a continuous platinum thin film can always be formed at higher loadings. As the loading of platinum is decreased on all of the support materials studied, the activity eventually decreases, corresponding to effective platinum coverages that form nucleated particles on the support. The effective platinum coverage at which a continuous layer of platinum is formed, and exhibits the high activity, depends strongly on the support. The critical effective coverage, below which the oxygen reduction activity decreases, is ca. 5ML on anatase, and slightly higher on the amorphous phase of titania. Doping the titania with tin 10at.%>Sn>0% initially results in an increase in this critical effective coverage. At higher tin concentrations this critical coverage reduces again, and for supports with 23at.%<Sn<40at.%, only ca. 1.6ML is required. Therefore, these catalysts have the highest mass activity. Stability cycling of these catalysts also shows that they are the more stable supported systems. It is also shown that the doped titania support material itself is stable in a sulphuric acid environment at 80°C for Sn<at 28%. These results suggest that active and stable titania supported catalysts can be formed on tin doped supports with concentrations in the range 28at.%>Sn>23at.%.

XRD, UV-Vis-NIR and FT-IR Studies of ITO and Cr: ITO Thin Films Prepared by Electron Beam Evaporation Technique

The Indium-tin-oxide (ITO) and Cr doped ITO thin films were prepared using electron beam evaporation technique. The prepared thin films were subjected to structural and optical properties. From the XRD it was observed that the films were crystalline in nature with cubic structure. The crystallite size was calculated using Scherer's relation and found that it was about 25 nm. The optical transmittance and absorbance spectra were recorded using UV-Vis-NIR spectrophotometer. From these, the optical band gap of ITO and Cr:ITO thin films were found to be 4.0 ev and 3.97 eV, respectively. The Fourier transform-Infrared spectroscopy study showed the peaks at 292, 519, 804, 957, 114, 1387 and 2985 cm-1 which are characteristic of In-O bonds. Introduction. It is known that extensive work is being carried out on optical and electrical properties of wide band gap oxide semiconductors such as ZnO, TiO2, SnO2, In2O3, Cu2O etc. [1-7]. Among the other oxide semiconductors, In2O3 is the one of the best suited materials for many electronic applications. It is a transparent, degenerate n-type wide band gap semiconductor with cubic structure in which the optical and electrical properties can be varied by doping of tin (Sn) or creating off stoichiometry. In In2O3 lattice if 10% of Tin (Sn) is doped the resultant material indium-tin-oxide is called as ITO [8, 9]. Due to its peculiar properties of high electrical conductivity and high optical transmittance in visible region it finds numerous applications such as nano electronics, opto electronics, sensor devices, flat panel displays and energy storage devices [10-18]. However, the studies of magnetic properties of ITO and impurity doped ITO thin films are meager. Recently continuous efforts are being put on magnetic properties of ITO and doped ITO nanoparticles, thin films and nanostructures. At present, this paper has been focused more on the structural and optical properties of ITO and Cr:ITO thin films and magnetic studies will be carried out in the future.

Virtual gap states induced modifications in charge neutrality level in cadmium oxide thin films

Present manuscript reports on the creation of virtual gap states (ViGS) in sol–gel spin coated cadmium oxide thin films by tin doping and irradiation at different density of electronic excitations (EEs) induced by energetic ions. Effects of ViGS on charge neutrality level (CNL), which affects the modifications in band gap (BG) of such oxide semiconductors are investigated. Studies reveal that there were insignificant changes in the structural and morphological properties of the films. Interestingly, the transmittance spectrum shows insignificant changes in the films irradiated by low density EEs but an overall decrease in transmittance for high density EEs. However, Raman spectroscopy reveals a significant change in longitudinal optical (LO) modes with tin doping which get intensified and they exhibit an insignificant influence upon irradiation. The BG with respect to bulk is observed to be increased by 0.57 eV and 0.83 eV upon tin doping and irradiation, respectively. These variations are attributed to the combined effect of Burstein–Moss shift (BMS) and ViGS, which were created by tin doping and EEs. It is observed that density of ViGS strongly depends on the density of EEs. A schematic band diagram is also developed for demonstrating the observed influence of ViGS on band gap modifications. Thus the reported investigations are very interesting for the in-depth understanding of fundamental interactions and besides their possible potential applications in the development of optoelectronic devices.

Sn-doped ZnO nanopetal networks for efficient photocatalytic degradation of dye and gas sensing applications

Nowadays, tremendous increase in environmental issue is an alarming threat to the ecosystem. This paper reports, rapid synthesis and characterization for tin doped ZnO nanoparticles prepared by simple combustion method and doctor blade technique. The prepared nanoparticles were characterized by several techniques in terms of their morphological, structural, compositional, optical, photocatalytic and gas sensing properties. These detailed characterization confirmed that all the synthesized nanoparticles are well crystalline and having good optoelectronic properties. Herein, different concentrations of Sn (0.5 at. wt%, 1.0 at. wt%, 2.0 at. wt%, 3.0 at. wt%) were used as dopants (SZ1–SZ4). The morphology of synthesized technique confirmed that the petal-shaped nanoparticles has high surface area and are well crystalline. In order to develop smart and functional nano-device, the prepared powder was coated on glass substrate by doctor blade technique and fabricated device was sensed for ethanol and acetone gas at different operating temperatures (300–500̊C). It is noteworthy that morphology of the nanoparticles of the sensitive layer is maintained after different concentration of Sn. High sensitivity is the main cause of high surface area and tin doping. PL intensity near 598nm of SZ3 is greater than other Sn-doped ZnO which indicates more oxygen vacancies of SZ3 is responsible for enhanced gas sensitivity and photocatalytic activity. The sensing performance showed 5% volume of ethanol and acetone and gases could be detected with sensitivity of 86.80% and 84.40% respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory. Sn–ZnO was used as photocatalyst for degradation of DR-31 dye. Optimum concentration of prepared nanoparticles (2.0 at. wt%) exhibits complete degradation of dye only in 60min under UV irradiation.

Characterization of Sn Doped ZnS Thin Films Synthesized by CBD

Zinc sulphide (ZnS) thin film were prepared using chemical bath deposition (CBD) process and tin (Sn) doping was successfully carried out in ZnS. Structural, morphological and microstructural characterization was carried out using XRD, TEM, FESEM and EDX. XRD and SAED pattern confirms presence of hexagonal phase. Reitveld analysis using MAUD software was used for particle size estimation. A constantly decreasing trend in particle size was observed with increasing tin incorporation in ZnS film which was due to enhanced microstrain resulting for tin incorporation. The particle size of prepared hexagonal wurtzite ZnS was around 14-18 nm with average size of ~16.5 nm. The bandgap of the film increases from ~ 3.69 eV for ZnS to ~ 3.90 eV for 5% Sn doped ZnS film which might be due to more ordered hexagonal structure as a result of tin incorporation. Band gap tenability property makes Sn doped ZnS suitable for application in different optoelectronics devices. PL study shows variation of intensity with excitation wavelength and a red shift is noticed for increasing excitation wavelength.

Spin-coated Tin-doped NiO thin films for third order nonlinear optical applications

A self-made spin-coater was employed to deposit pure and Sn doped nickel oxide thin films on glass substrates. The tin doping impact on the structural, linear and nonlinear optical properties of the spin-coated NiO thin films was studied. The XRD analysis showed that undoped and Sn doped NiO thin films have a cubic structure and are preferentially oriented along the (200) direction. The increase of doping concentration leads to a modification in the values of certain parameters such as the crystallite size and the structural strain as well as affecting the nonlinear optical properties of the doped nickel oxide thin films. The values of the third order nonlinear optical susceptibility, found to be between 2.25×10−21m2/V2 and 3.13×10−21m2/V2, were obtained and analyzed depending on the concentration of the doping.

Correlations of charge neutrality level with electronic structure and p-d hybridization

The formation of charge neutrality level (CNL) in highly conducting Cadmium oxide (CdO) thin films is demonstarted by the observed variation in the band gap upon annealing and doping. It may be explained by the observation that Tin (Sn) doping breaks the perfect periodicity of CdO cubic crystal structure and creates virtual gap states (ViGS). The level of local CNL resides at the branch point of ViGS, making the energy at which native defect’s character changes from predominantly donor-like below CNL to predominantly acceptor-like above the CNL and a schematic band diagram is developed to substantiate the same. Further investigations using soft x-ray absorption spectroscopy (SXAS) at Oxygen and Cadmium edges show the reduction of Sn4+ to Sn2+. The analysis of the spectral features has revealed an evidence of p-d interaction between O 2p and Cd 4d orbitals that pushes the valence band minima at higher energies which is symmetry forbidden at г point and causing a positive valance band dispersion away from the zone centre in the г ~ L, K direction. Thus, origin of the CNL is attributed to the high density of the Oxygen vacancies as confirmed by the change in the local electronic structure and p-d hybridization of orbitals.

Thermoelectric properties of Bi1-xSnxCuSeO solid solutions.

We report the enhanced thermoelectric properties of p-type BiCuSeO by tin doping on bismuth sites. Powder X-ray diffraction analysis and Hall measurements indicated effective tin doping in all samples. We found that the doping efficiency of Sn is lower than expected, as seen from the measured carrier concentration. First-principles calculations indicate that the Sn lone pair modifies the band structure at the Fermi level, with the consequent effect observed in the electrical transport and Seebeck coefficient measurements. An enhanced thermoelectric power factor of ∼2.5 μW cm-1 K-2 was reached at 773 K. No significant effect of Sn doping on the thermal conductivity was found; a thermoelectric figure of merit value (ZT) of 0.3 at 773 K is achieved for Bi0.9Sn0.1CuSeO, which is more than twice that of the pristine BiCuSeO.

Adjusting the band structure and defects of ZnO quantum dots via tin doping

The structures and band structures of Sn doped ZnO were investigated by density functional theory as well as experiment.

Effect of (Al, Sn) doping on structural, magnetic and magnetocaloric properties of La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 (0 ≤ x,y ≤ 0.075) manganites

The effect of aluminum and tin doping on the microstructure, magnetic and magnetocaloric effects in La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 (0 ≤ x,y ≤ 0.075) manganite compounds has been investigated. All the samples have been elaborated using the conventional sol-gel method. X-ray diffraction (XRD) analysis using Rietveld refinement has shown that all the samples under investigation crystallize in the rhombohedral structure with R3¯ c space group. The magnetic properties of these compounds are discussed in detail, based on magnetization and the inverse of susceptibility, over a wide temperature range (T = 0–350 K). Magnetization measurements versus temperature in a magnetic applied field of 0.05 T showed that all our investigated samples display a paramagnetic–ferromagnetic transition with decreasing temperature. From the measured magnetization data of La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 samples as a function of magnetic applied field, the associated magnetic entropy change |Δ SM | and the relative cooling power RCP have been determined. In the vicinity of TC, |Δ SM | reached, in a magnetic applied field of 5 T, maximum values of 3.7 J/kg K, 2.7 J/kg K 2.3 J/kg K and 2 J/kg K for x, y = 0.0, 0.025, 0.05 and 0.075 respectively.

Electrical and structural characteristics of tin-doped GaN thin films and its hetero-junction diode made all by RF reactive sputtering

Tin (Sn) doping in gallium nitride (GaN) has been mainly reported from the theoretical view only. Based upon the availability of Sn precursor and commercialization, Sn-GaN film has not been deposited magnetron sputtering until this work. By using the cheap and safe reactive sputtering technique, here we present Sn-GaN thin films with single cermet targets at the Sn/(Sn+Ga) molar ratios of x=0, 0.03, 0.07, and 0.1 to form Sn-x-GaN films under the atmosphere of the mixture of Ar and N2. The Sn-GaN films had the wurtzite structure. Sn can be added to GaN to form SnGaN alloy with a maximal amount of ~10%. The structural, electrical, and optical properties had changed with the Sn content until the oversaturation of Sn in Sn-0.1-GaN. The Sn doping led to the lattice expansion, worsened crystallinity, n-type GaN, increased electrical concentration, decreased the electrical mobility etc. Moreover, n-Sn-x-GaN/p-Si diodes were successfully made and their performance was evaluated in terms of the barrier height, ideality factor, and series resistance. This work has opened the door for studying the different kinds of dopants on the important III nitrides.

On the effect of Sn-doping in hematite anodes for oxygen evolution

Iron (III) oxide applications as anodic material in electrocatalysis and photoelectrochemical cells are currently limited by its poor electric properties. To overcome these issues, doping has been applied with some success and high-temperature (800°C) treatment on fluorine doped tin oxide substrates, leading to tin-doping, is now a widely employed procedure to activate hematite anodes. In this paper we undertake a systematic investigation of the effects of tin doping on the structural, optical and electrochemical properties of hematite thin films, focusing on the anodic performance towards water splitting. To isolate the effect of doping from those of morphology and crystallinity, we devise a fabrication method based on radio-frequency magnetron sputtering yielding crystalline hematite at room temperature, thus enhancing the compatibility towards substrates and the potential for application. Doping in the range 1-12% (atomic) induces lattice distortion with cell volume increase and a substantial extension of the visible absorption range due to a band-gap narrowing of about 0.45eV for the highest doping level. The electrode metrics are greatly improved, with a shift of up to 60mV towards less positive overpotentials and Tafel slopes about the half of the original value. The best performance is found for a 6.2 at. % doping, with η=441mV (at j=1mA/cm2) and a 48mV/dec Tafel slope, in line with current state-of-the-art results reported for amorphous iron based catalysts. In our case tin doping leads to improved conductivity and to a decreased (up to 1 order of magnitude) interfacial charge transfer resistance, as revealed by electrochemical impedance spectroscopy.

Shape-controlled synthesis of Sn-doped CuO nanoparticles for catalytic degradation of Rhodamine B

The uniform Sn-doped CuO nanoparticles were synthesized by a simple solution method at a low temperature. The prepared samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy techniques (HRSEM, HRTEM, SAED, STEM and EDS elemental mapping), atomic force microscopy (AFM), UV/Vis spectroscopy, nitrogen physisorption (BET) and by evaluation of the catalytic activity on the degradation of Rhodamine B. The tin doping had a considerable influence on the morphology of CuO. The gradual narrowing of the particles morphology in the crystallographic [010] direction was observed with increasing the dopant concentration. The plate-like, rectangularsquare and rod-like CuO nanoparticles were obtained. The mechanism of a crystal growth of CuO associated with doping is proposed. The tin doping also affected the structural and optical properties of CuO. Increasing the amount of a dopant led to a red-shift of a band gap from 1.33 to 1.18eV. The incorporation of tin into the structure of copper oxide was confirmed by XRD and distribution of tin mapped by EDS analysis. The good catalytic properties of the as-prepared doped material were demonstrated by the enhanced catalytic removal of Rhodamine B in the presence of H2O2. The undoped CuO nanosheets reached only 24% efficiency in the removal of Rhodamine B within two hours. The best result exhibited CuO_050Sn sample containing 4at.% of tin and the degradation of Rhodamine B reached 99% within the same time. We have demonstrated a simple, scalable process for the preparation of catalytically very active Sn-doped CuO nanoparticles with varying properties.

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices.

Electronic structure and optical property studies of wurtzite AgInS2 doped by tin

The electronic structure and optical property of wurtzite AgInS2 with vacancy defects and tin doping have been investigated by the first principle based on density functional theory. The results show that the intrinsic silver and indium vacancy may lead to the narrowing of bandgap. It shows metal characteristic after a silver atom and an indium atom are respectively replaced by tin atoms in the supercell of wurtzite AgInS2. The optical property study indicates that the absorption curves and reflectivity curves of AgInS2 are blue shift and weakened owing to the existence of vacancy defects and tin doping.