Tin Acetylacetonate Research Articles

Improved resistive switching characteristics of solution processed ZrO2/SnO2 bilayer RRAM via oxygen vacancy differential

In this study, a solution-processed bilayer structure ZrO2/SnO2 resistive switching (RS) random access memory (RRAM) is presented for the first time. The precursors of SnO2 and ZrO2 are Tin(Ⅱ) acetylacetonate (Sn(AcAc)2) and zirconium acetylacetonate (Zr(C5H7O2)4), respectively. The top electrode was deposited with Ti using an E-beam evaporator, and the bottom electrode used an indium–tin–oxide glass wafer. We created three devices: SnO2 single-layer, ZrO2 single-layer, and ZrO2/SnO2 bilayer devices, to compare RS characteristics such as the I–V curve and endurance properties. The SnO2 and ZrO2 single-layer devices showed on/off ratios of approximately 2 and 51, respectively, along with endurance switching cycles exceeding 50 and 100 DC cycles. The bilayer device attained stable RS characteristics over 120 DC endurance switching cycles and increased on/off ratio ∼2.97 × 102. Additionally, the ZrO2/SnO2 bilayer bipolar switching mechanism was explained by considering the Gibbs free energy (ΔG o) difference in the ZrO2 and SnO2 layers, where the formation and rupture of conductive filaments were caused by oxygen vacancies. The disparity in the concentration of oxygen vacancies, as indicated by the Gibbs free energy difference between ZrO2 (ΔG o = −1100 kJ mol−1) and SnO2 (ΔG o = −842.91 kJ mol−1) implied that ZrO2 exhibited a higher abundance of oxygen vacancies compared to SnO2, resulting in improved endurance and on/off ratio. X-ray photoelectron spectroscopy analyzed oxygen vacancies in ZrO2 and SnO2 thin films. The resistance switching characteristics were improved due to the bilayer structure, which combines a higher oxygen vacancy concentration in one layer with a lower oxygen vacancy concentration in the switching layer. This configuration reduces the escape of oxygen vacancies to the electrode during RS.

Impact of air exposure on growth rate and electrical properties of SnO2 thin films by atmospheric pressure spatial atomic layer deposition

SnO2 thin film is one of the most studied transparent conductive materials that can be deposited using vacuum-free techniques such as atmospheric pressure spatial atomic layer deposition (AP-SALD). This work studies SnO2 thin films prepared from tin(II) acetylacetonate and water vapor, with a particular focus on the impact of air exposure during the AP-SALD process on the growth rate and electrical properties of the films. In-situ resistance measurements and ex-situ Hall effect characterization demonstrated that longer exposure time of the growing film surface to the open air (t air) at 240 °C led to conductivity degradation, while the film thickness decreases. The theoretical calculations show that −OH and (oxygen molecule adsorbed on the five-coordinated Sn atom, also called O2 dimer) are the two most stable surface structures. The formation of is shown as the most thermodynamically favorable oxygen-related species on SnO2(110) surface formed when the film is exposed to the open air, giving rise to both the decrease of film thickness (associated with the desorption of −OH surface groups) and the increase of film resistivity versus t air. The optimized polycrystalline SnO2 sample demonstrated relatively good electrical performance, including an electrical resistivity of 9.3 × 10−3 Ω.cm, carrier density of 9.2 × 1019 cm−3, and Hall mobility of 7.3 cm2 V−1 s−1 at a growth temperature as low as 240 °C. Our findings reveal the critical impact of processing in the open air on the electrical conductivity of the obtained SnO2 films by AP-SALD coating technology.

Atmospheric Pressure Solvothermal Synthesis of Nanoscale SnO2 and Its Application in Microextrusion Printing of a Thick-Film Chemosensor Material for Effective Ethanol Detection.

The atmospheric pressure solvothermal (APS) synthesis of nanocrystalline SnO2 (average size of coherent scattering regions (CSR)-7.5 ± 0.6 nm) using tin acetylacetonate as a precursor was studied. The resulting nanopowder was used as a functional ink component in microextrusion printing of a tin dioxide thick film on the surface of a Pt/Al2O3/Pt chip. Synchronous thermal analysis shows that the resulting semiproduct is transformed completely into tin dioxide nanopowder at 400 °C within 1 h. The SnO2 powder and the resulting film were shown to have a cassiterite-type structure according to X-ray diffraction analysis, and IR spectroscopy was used to establish the set of functional groups in the material composition. The microstructural features of the tin dioxide powder were analyzed using scanning (SEM) and transmission (TEM) electron microscopy: the average size of the oxide powder particles was 8.2 ± 0.7 nm. Various atomic force microscopy (AFM) techniques were employed to investigate the topography of the oxide film and to build maps of surface capacitance and potential distribution. The temperature dependence of the electrical conductivity of the printed SnO2 film was studied using impedance spectroscopy. The chemosensory properties of the formed material when detecting H2, CO, NH3, C6H6, C3H6O and C2H5OH, including at varying humidity, were also examined. It was demonstrated that the obtained SnO2 film has an increased sensitivity (the sensory response value was 1.4-63.5) and selectivity for detection of 4-100 ppm C2H5OH at an operating temperature of 200 °C.

Ionic Liquid-Mediated Route to Atomic Layer Deposition of Tin(II) Oxide via a C-C Bond Cleavage Ligand Modification Mechanism.

Atomic layer deposition (ALD) is a technologically important method to grow thin films with high conformality and excellent thickness control from vapor phase precursors. The development of new thermal ALD processes can be limited by precursor reactivity and stability: reaction temperature and precursor design are among the few variables available to achieve higher reactivity in gas-phase reactions, unlike in solution synthesis, where the use of solvent and/or a catalyst can promote a desired reaction. To bridge this synthesis gap between vapor-phase and solution-phase, we demonstrate the use of an ultrathin coating layer of a vapor phase-compatible solvent─an ionic liquid (IL)─on our growth substrate to perform ALD of SnO. Successful SnO deposition is achieved using tin acetylacetonate and water, a process that otherwise would require a stronger counter-reactant such as ozone. The presence of the layer of IL allows a solvent-mediated reaction mechanism to take place on the growth substrate surface. We report a growth per cycle of 0.67 Å/cycle at a deposition temperature of 100 °C in an IL comprising 1-ethyl-3-methylimidazolium hydrogen sulfate. Characterization of the ALD films confirms the SnO film composition, and 1H and 13C NMR are used to probe the solvent-mediated ALD reaction, suggesting a solvent-mediated addition-elimination-type mechanism which breaks a C-C bond in acetylacetonate to form acetone and acetate. Density functional theory calculations show that the IL solvent is beneficial to the proposed solvent-mediated mechanism by lowering the C-C bond cleavage energetics of acetylacetonate compared to the vapor phase. A general class of ligand modification reactions for thermal ALD is thus introduced in this work.

Atmospheric atomic layer deposition of SnO2 thin films with tin(II) acetylacetonate and water.

Due to its unique optical, electrical, and chemical properties, tin dioxide (SnO2) thin films attract enormous attention as a potential material for gas sensors, catalysis, low-emissivity coatings for smart windows, transparent electrodes for low-cost solar cells, etc. However, the low-cost and high-throughput fabrication of SnO2 thin films without producing corrosive or toxic by-products remains challenging. One appealing deposition technique, particularly well-adapted to films presenting nanometric thickness is atomic layer deposition (ALD). In this work, several metalorganic tin-based complexes, namely, tin(IV) tert-butoxide, bis[bis(trimethylsilyl)amino] tin(II), dibutyltin diacetate, tin(II) acetylacetonate, tetrakis(dimethylamino) tin(IV), and dibutyltin bis(acetylacetonate), were explored thanks to DFT calculations. Our theoretical calculations suggest that the three last precursors are very appealing for ALD of SnO2 thin films. The potential use of these precursors for atmospheric-pressure spatial atomic layer deposition (AP-SALD) is also discussed. For the first time, we experimentally demonstrate the AP-SALD growth of SnO2 thin films using tin(II) acetylacetonate (Sn(acac)2) and water. We observe that Sn(acac)2 exhibits efficient ALD activity with a relatively large ALD temperature window (140-200 °C), resulting in a growth rate of 0.85 ± 0.03 Å per cyc. XPS analyses show a single Sn 3d5/2 characteristic peak for Sn4+ at 486.8 ± 0.3 eV, indicating that a pure SnO2 phase is obtained within the ALD temperature window. The as-deposited SnO2 thin films are in all cases amorphous, and film conductivity increases with the deposition temperature. Hall effect measurements confirm the n-type nature of SnO2 with a free electron density of about 8 × 1019 cm-3, electron mobility up to 11.2 cm2 V-1 s-1, and resistivity of 7 × 10-3 Ω cm for samples deposited at 270 °C.

Tin(II) Acetylacetonate as a New Type of Tin Compensator Additive for Tin-Based Perovskite Solar Cells.

Tin (Sn)-based perovskite is one of the most promising candidates for lead (Pb)-free perovskite light-absorbing materials applied in solar cells. However, the intrinsic Sn vacancy (VSn) defects seriously hinder the device performance, making the reported maximum power efficiency (PCE) of Sn-based perovskite solar cells (PSCs) far behind those of Pb-based ones. During the study, SnF2 has been demonstrated as an indispensable Sn compensator additive to improve the device performance. Considering that the default use of SnF2 and the selection of a Sn compensator has also been limited to tin(II) halides, i.e., SnCl2, SnBr2, and SnI2, the role and work mechanism of the Sn compensator have not yet been clarified clearly. Herein, a new type of Sn compensator, tin(II) acetylacetonate [Sn (acac)2], is introduced into Sn-based PSCs. It is found that in addition to tin compensation, the organic ligand acac- can coordinate with Sn2+ in the precursor solution and improve the crystallization process of perovskites. Consequently, the maximum PCE of formamidinium tin triiodide (FASnI3) solar cells is enhanced from 3.88 to 7.27% using Sn (acac)2 as the Sn compensator.

Substrate Effects on Crystal Phase in Atomic Layer Deposition of Tin Monosulfide

Obtaining single-phase tin monosulfide (SnS) films at low temperatures is challenging since cubic (π-SnS) and orthorhombic (α-SnS) polymorphs have similar energies of formation and grow under similar conditions. Here, we show that in atomic layer deposition (ALD) of polycrystalline SnS using tin(II) acetylacetonate and H2S precursors, the substrate surface greatly influences the SnS phase evolution. For example, a silicon (100) substrate, with a highly hydroxylated surface, favors the growth of α-SnS. Meanwhile, ozone treatment or preannealing of the same substrate leads to mainly π-SnS. Just a few ALD cycles of another oxide or sulfide can even more substantially alter the outcome. Substrates that favor α-SnS growth typically produce initially enhanced growth rates, while those promoting π-SnS are partially surface-poisoned by the acetylacetonate precursor ligands. Growth of either polymorph is self-sustained after its initiation, and the sustaining factor appears to be the surface–ligand interaction; π-SnS preferentially evolves on substrates and π-SnS surfaces that are rich in highly reactive dangling bonds, while chemically inert substrates and α-SnS surfaces promote α-SnS. While lattice matching is less central, the role of ligand bonding in SnS ALD also helps explain the previously reported phase dependence on growth temperature and H2S precursor dose and shows promise for area-selective ALD of SnS.

Resistive switching characteristics of UV-assisted room-temperature-fabricated top-electrode-free SnOx ReRAM

We investigated the resistive switching characteristics of a top-electrode-free SnOx-based resistive switching random access memory (ReRAM) which was fabricated at room temperature. The resistive switching layer was deposited by assistance of UV irradiation after two instances of spin coating of the Tin(II) acetylacetonate (Sn(AcAc)2) precursor. To minimize the coffee ring effect, the mixture of 2-methoxyethanol and ethanol was used as a solvent of the precursor. The resistive switching characteristics of the top-electrode-free device was measured by direct contact of a tungsten probe tip on the SnOx thin film in reference to the bottom ITO electrode. The device fabricated with 8 h of UV irradiation showed stable resistive switching characteristics even after repeating DC sweep switching cycles 200 times. The retention of the fabricated device was over 104 s. It was found that the Ohmic conduction is dominant in the low resistive state and the space charge limited conduction is dominant in the high resistive state. The resistive switching mechanism of this device was proposed as the tin ion-based filament-type ReRAM. The UV irradiation effects on the SnOx thin film were examined by x-ray photoelectron spectroscopy and the SnOx film thickness depending on the time of UV irradiation was measured by a field emission scanning electron microscope.

Microemulsion Synthesis of SnO2 Spheres Using Tin Acetylacetonate as a Precursor

The process for preparing SnO2 nanocrystalline microspheres via synthesis in microemulsions combined with hydrothermal treatment of the resulting suspensions was studied. Tin acetylacetonate, whose n‑butanol solution is more convenient for use compared to classical reagents, was shown to have a promise for use as a precursor. Simultaneous thermal analysis and IR spectroscopy showed the transformation of a hydrated powder under heating to yield anhydrous tin dioxide. SEM analysis of the prepared SnO2 powder microstructure elucidated a two-level organization of oxide particles—nanoparticles with a size of about 25 nm were hierarchically organized in the form of medium-sized microspheres of about 1.5 µm, were formed during microemulsion synthesis upon tin acetylacetonate hydrolysis.

Stable perovskite solar cells using tin acetylacetonate based electron transporting layers

High performing planar-type perovskite solar cells and mini-modules are fabricated by incorporating passivated tin oxide based on non-colloidal acetylacetonate precursors.

Thermal Atomic Layer Etching of Silica and Alumina Thin Films Using Trimethylaluminum with Hydrogen Fluoride or Fluoroform.

Thermal atomic layer etching (ALE) is an emerging technique that involves the sequential removal of monolayers of a film by alternating self-limiting reactions, some of which generate volatile products. Although traditional ALE processes rely on the use of plasma, several thermal ALE processes have recently been developed using hydrogen fluoride (HF) with precursors such as trimethylaluminum (TMA) or tin acetylacetonate. While HF is currently the most effective reagent for ALE, its potential hazards and corrosive nature have motivated searches for alternative chemicals. Herein, we investigate the feasibility of using fluoroform (CHF3) with TMA for the thermal ALE of SiO2 and Al2O3 surfaces and compare it to the established TMA/HF process. A fundamental mechanistic understanding is derived by combining in situ Fourier transform infrared spectroscopy, ex situ X-ray photoemission spectroscopy, ex situ low-energy ion scattering, and ex situ spectroscopic ellipsometry. Specifically, we determine the role of TMA, the dependence of the etch rate on precursor gas pressure, and the formation of a residual fluoride layer. Although CHF3 reacts with TMA-treated oxide surfaces, etching is hindered by the concurrent deposition of a fluorine-containing layer, which makes it unfavorable for etching. Moreover, since fluorine contamination can be deleterious to device performance and its presence in thin films is an inherent problem for established ALE processes using HF, we present a novel method to remove the residual fluorine accumulated during the ALE process by exposure to water vapor. XPS analysis herein reveals that an Al2O3 film etched using TMA/HF at 325 °C contains 25.4 at. % fluorine in the surface region. In situ exposure of this film to water vapor at 325 °C results in ∼90% removal of the fluorine. This simple approach for fluorine removal can easily be applied to ALE-treated films to mitigate contamination and retain surface stoichiometry.

Tin Acetylacetonate as a Precursor for Producing Gas-Sensing SnO2 Thin Films

To expand the range of precursors used in the sol–gel technology for applying nanostructured SnO2 thin films promising as components of semiconductor chemical gas sensors, the efficiency of using tin acetylacetonate solutions with various precursor concentrations was demonstrated. It was determined that finely divided SnO2 with a crystallite size of 3–4 nm (cassiterite) can be obtained by hydrolysis by atmospheric moisture in the course of solvent evaporation at room temperature. Using tin acetylacetonate solutions with various precursor concentrations for applying SnO2 thin films by dip coating to the surface of rough ceramic Al2O3-based substrates with platinum interdigital electrodes and a microheater resulted in significant differences in microstructure, continuity, thickness, and porosity of the produced coatings. In a lower-concentration (0.13 mol/L) tin acetylacetonate solution, a multilayer dense continuous SnO2 coating was applied, whereas in a higher-concentration (0.25 mol/L) solution, the formed layer comprised aggregated nanoparticles 30–60 nm in size and had much more defects and higher porosity. The sensitivity of the obtained thin-film nanostructures to the most practically important gaseous analytes: CO, H2, CH4, CO2, and NO2. The produced two-dimensional nanomaterials were shown to be promising for detecting carbon monoxide at 200–300°C in dry air.

Selectivity in Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange Reactions

Atomic layer etching (ALE) can result from sequential, self-limiting thermal reactions. The reactions during thermal ALE are defined by fluorination followed by ligand exchange using metal precursors. The metal precursors introduce various ligands that may transfer during ligand exchange. If the transferred ligands produce stable and volatile metal products, then the metal products may leave the surface and produce etching. In this work, selectivity in thermal ALE was examined by exploring tin(II) acetylacetonate (Sn(acac)2), trimethylaluminum (TMA), dimethylaluminum chloride (DMAC), and SiCl4 as the metal precursors. These metal precursors provide acac, methyl, and chloride ligands for ligand exchange. HF-pyridine was employed as the fluorination reagent. Spectroscopic ellipsometry was used to measure the etch rates of Al2O3, HfO2, ZrO2, SiO2, Si3N4, and TiN thin films on silicon wafers. The spectroscopic ellipsometry measurements revealed that HfO2 was etched by all of the metal precursors. Al2O3 was et...

Thermal atomic layer etching of crystalline aluminum nitride using sequential, self-limiting hydrogen fluoride and Sn(acac)2 reactions and enhancement by H2 and Ar plasmas

Thermal atomic layer etching (ALE) of crystalline aluminum nitride (AlN) films was demonstrated using sequential, self-limiting reactions with hydrogen fluoride (HF) and tin(II) acetylacetonate [Sn(acac)2] as the reactants. Film thicknesses were monitored versus number of ALE reaction cycles at 275 °C using in situ spectroscopic ellipsometry (SE). A low etch rate of ∼0.07 Å/cycle was measured during etching of the first 40 Å of the film. This small etch rate corresponded with the AlOxNy layer on the AlN film. The etch rate then increased to ∼0.36 Å/cycle for the pure AlN films. In situ SE experiments established the HF and Sn(acac)2 exposures that were necessary for self-limiting surface reactions. In the proposed reaction mechanism for thermal AlN ALE, HF fluorinates the AlN film and produces an AlF3 layer on the surface. The metal precursor, Sn(acac)2, then accepts fluorine from the AlF3 layer and transfers an acac ligand to the AlF3 layer in a ligand-exchange reaction. The possible volatile etch products are SnF(acac) and either Al(acac)3 or AlF(acac)2. Adding a H2 plasma exposure after each Sn(acac)2 exposure dramatically increased the AlN etch rate from 0.36 to 1.96 Å/cycle. This enhanced etch rate is believed to result from the ability of the H2 plasma to remove acac surface species that may limit the AlN etch rate. The active agent from the H2 plasma is either hydrogen radicals or radiation. Adding an Ar plasma exposure after each Sn(acac)2 exposure increased the AlN etch rate from 0.36 to 0.66 Å/cycle. This enhanced etch rate is attributed to either ions or radiation from the Ar plasma that may also lead to the desorption of acac surface species.

Prospects for Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange Reactions.

Thermal atomic layer etching (ALE) of Al2O3 and HfO2 using sequential, self-limiting fluorination and ligand-exchange reactions was recently demonstrated using HF and tin acetylacetonate (Sn(acac)2) as the reactants. This new thermal pathway for ALE represents the reverse of atomic layer deposition (ALD) and should lead to isotropic etching. Atomic layer deposition and ALE can together define the atomic layer growth and removal steps required for advanced semiconductor fabrication. The thermal ALE of many materials should be possible using fluorination and ligand-exchange reactions. The chemical details of ligand-exchange can lead to selective ALE between various materials. Thermal ALE could produce conformal etching in high-aspect-ratio structures. Thermal ALE could also yield ultrasmooth thin films based on deposit/etch-back methods. Enhancement of ALE rates and possible anisotropic ALE could be achieved using radicals or ions together with thermal ALE.

Mechanism of Thermal Al2O3 Atomic Layer Etching Using Sequential Reactions with Sn(acac)2 and HF

Thermal Al2O3 atomic layer etching (ALE) can be performed using sequential, self-limiting reactions with tin(II) acetylacetonate (Sn(acac)2) and HF as the reactants. To understand the reaction mech...

Atomic layer etching of Al2O3 using sequential, self-limiting thermal reactions with Sn(acac)2 and hydrogen fluoride.

The atomic layer etching (ALE) of Al2O3 was demonstrated using sequential, self-limiting thermal reactions with tin(II) acetylacetonate (Sn(acac)2) and hydrogen fluoride (HF) as the reactants. The Al2O3 samples were Al2O3 atomic layer deposition (ALD) films grown using trimethylaluminum and H2O. The HF source was HF-pyridine. Al2O3 was etched linearly with atomic level precision versus number of reactant cycles. The Al2O3 ALE was monitored at temperatures from 150 to 250 °C. Quartz crystal microbalance (QCM) studies revealed that the sequential Sn(acac)2 and HF reactions were self-limiting versus reactant exposure. QCM measurements also determined that the mass change per cycle (MCPC) increased with temperature from -4.1 ng/(cm(2) cycle) at 150 °C to -18.3 ng/(cm(2) cycle) at 250 °C. These MCPC values correspond to etch rates from 0.14 Å/cycle at 150 °C to 0.61 Å/cycle at 250 °C based on the Al2O3 ALD film density of 3.0 g/cm(3). X-ray reflectivity (XRR) analysis confirmed the linear removal of Al2O3 and measured an Al2O3 ALE etch rate of 0.27 Å/cycle at 200 °C. The XRR measurements also indicated that the Al2O3 films were smoothed by Al2O3 ALE. The overall etching reaction is believed to follow the reaction Al2O3 + 6Sn(acac)2 + 6HF → 2Al(acac)3 + 6SnF(acac) + 3H2O. In the proposed reaction mechanism, the Sn(acac)2 reactant donates acac to the substrate to produce Al(acac)3. The HF reactant allows SnF(acac) and H2O to leave as reaction products. The thermal ALE of many other metal oxides using Sn(acac)2 or other metal β-diketonates, together with HF, should be possible by a similar mechanism. This thermal ALE mechanism may also be applicable to other materials such as metal nitrides, metal phosphides, metal sulfides and metal arsenides.

Atomic Layer Etching of HfO2 Using Sequential, Self-Limiting Thermal Reactions with Sn(acac)2 and HF

The atomic layer etching (ALEt) of HfO2 was performed using sequential, self-limiting thermal reactions with tin(II) acetylacetonate (Sn(acac)2) and HF as the reactants. The HF source was a HF-pyridine solution. The etching of HfO2 was linear with atomic level control versus number of Sn(acac)2 and HF reaction cycles. The HfO2 ALEt was measured at temperatures from 150–250°C. Quartz crystal microbalance (QCM) measurements determined that the mass change per cycle (MCPC) increased with temperature from −6.7 ng/(cm2 cycle) at 150°C to −11.2 ng/(cm2 cycle) at 250°C. These MCPC values correspond to etch rates from 0.070 Å/cycle at 150°C to 0.117 Å/cycle at 250°C. X-ray reflectivity analysis confirmed the linear removal of HfO2 and measured an HfO2 ALEt etch rate of 0.11 Å/cycle at 200°C. Fourier transform infrared (FTIR) spectroscopy measurements also observed HfO2 ALEt using the infrared absorbance of the Hf-O stretching vibration. FTIR analysis also revealed absorbance features consistent with HfF4 or HfFx surface species as a reaction intermediate. The HfO2 etching is believed to follow the reaction: HfO2 + 4Sn(acac)2 + 4HF → Hf(acac)4 + 4SnF(acac) + 2H2O. In the proposed reaction mechanism, Sn(acac)2 donates acac to the substrate to produce Hf(acac)4. HF allows SnF(acac) and H2O to leave as reaction products. The thermal ALEt of many other metal oxides, as well as metal nitrides, phosphides, sulfides and arsenides, should be possible by a similar mechanism.

Growth behavior and properties of atomic layer deposited tin oxide on silicon from novel tin(II)acetylacetonate precursor and ozone

In this work, a novel liquid tin(II) precursor, tin(II)acetylacetonate [Sn(acac)2], was used to deposit tin oxide films on Si(100) substrate, using a custom-built hot wall atomic layer deposition (ALD) reactor. Three different oxidizers, water, oxygen, and ozone, were tried. Resulting growth rates were studied as a function of precursor dosage, oxidizer dosage, reactor temperature, and number of ALD cycles. The film growth rate was found to be 0.1 ± 0.01 nm/cycle within the wide ALD temperature window of 175–300 °C using ozone; no film growth was observed with water or oxygen. Characterization methods were used to study the composition, interface quality, crystallinity, microstructure, refractive index, surface morphology, and resistivity of the resulting films. X-ray photoelectron spectra showed the formation of a clean SnOx–Si interface. The resistivity of the SnOx films was calculated to be 0.3 Ω cm. Results of this work demonstrate the possibility of introducing Sn(acac)2 as tin precursor to deposit conducting ALD SnOx thin films on a silicon surface, with clean interface and no formation of undesired SiO2 or other interfacial reaction products, for transparent conducting oxide applications.

Microstructural, electrical and optical properties of indium tin oxide (ITO) nanoparticles synthesized by co-precipitation method

In the present study, the synthesis of Tin doped indium oxide (ITO) nanopowder at different compositions (In/Sn=0, 5, 10, 15at %) was carried out by co-precipitation method. The decomposition of precipitated indium tin acetylacetonate precursor to form In2O3–SnO2 (Sn1−xInxO2) at 400°C was confirmed by the thermal and FTIR studies. The changes in strain and grain size of the synthesized particle with respect to dopant concentration were determined from the X-ray diffraction (XRD) analysis. Transmission electron microscopy (TEM) images support to confirm the grain size. The optical properties on ITO nanoparticles were analyzed with UV–visible spectroscopy, and band gap was found to vary from 3.62 to 3.89eV with Sn dopant concentration. This variation was ascribed to the quantum confinement effect.