Nanostructured Tin Oxide Thin Films Research Articles

Self-Assembled Nanostructured Tin Oxide Thin Films at the Air–Water Interface for Selective H2S Detection

Simple, inexpensive and scalable strategies for metal oxide thin film growth are critical for potential applications in the field of gas sensing. Here, we report a general method for the synthesis ...

Synthesis of nano-structured tin oxide thin films with faster response to LPG and ammonia by spray pyrolysis

Nanostructured SnO2 thin film have been efficiently fabricated by spray pyrolysis using atomizers of different types. The structure and morphology of as-prepared samples are investigated by techniques such as x-ray diffraction, and field-emission scanning electron microscopy. Significant morphological changes are observed in films by modifying the precursor atomization as a result of change of spray device. The optical characterization indicates that change in atomization, affects the absorbance and the band gap, following the varied crystallite size. Gas sensing investigations on ultrasonically prepared tin oxide films show NH3 response at operating temperatures lower down to 50 °C. For 1000 ppm of LPG the response at 350 °C for air blast atomizer film is about 99%, with short response and recovery times. The photoluminescence emmision spectra reveal the correlation between atomization process and the quantity of oxygen vacancies present in the samples. The favorable size reduction in microstructure with good crystallinity with slight change in lattice properties suggest their scope in gas sensing applications. On the basis of these characterizations, the mechanism of LPG and NH3 gas sensing of nanostructured SnO2 thin films has been proposed.

Wet chemical synthesis of quantum confined nanostructured tin oxide thin films by successive ionic layer adsorption and reaction technique

Quantum confined nanostructured SnO2 thin films were synthesized at 353K using ammonium chloride (NH4Cl) and other chemicals by successive ionic layer adsorption and reaction technique. Film formation mechanism is discussed. Structural, morphological, optical and electrical properties were investigated and compared with the as-grown and annealed films fabricated without NH4Cl solution. SnO2 films were polycrystalline with crystallites of tetragonal structure with grain sizes lie in the 5–8nm range. Films with snow like crystallite morphology offer high specific surface area. The blue-shifted value of band gap of as-grown films confirmed the quantum confinement effect of grains. Refractive index of the films lies in the 2.1–2.3 range. Films prepared with NH4Cl exhibit relatively lower resistivity of the order of 100–10−1Ωcm. The present synthesis has advantages such as low cost, low temperature and green friendly, which yields small particle size, large surface–volume ratio, and high crystallinity SnO2 films.

Spray Pyrolysis Deposition of Nanostructured Tin Oxide Thin Films

Nanostructured SnO2 thin films were grown by the chemical spray pyrolysis (CSP) method. Homemade spray pyrolysis technique is employed to prepare thin films. SnO2 is wide bandgap semiconductor material whose film is deposited on glass substrate using aqueous solution of SnCl4·5H2O as a precursor. XRD (X-ray diffraction), UV (ultraviolet visible spectroscopy), FESEM (field emission scanning electron microscopy), and EDS (energy dispersive spectroscopy) analysis are done for structural, optical, surface morphological, and compositional analysis. XRD analysis shows polycrystalline nature of samples with pure phase formation. Crystallite size calculated from diffraction peaks is 29.92 nm showing nanostructured thin films. FESEM analysis shows that SnO2 thin film contains voids with nanoparticles. EDS analysis confirms the composition of deposited thin film on glass substrate. UV-visible absorption spectra show that the bandgap of SnO2 thin film is 3.54 eV. Bandgap of SnO2 thin film can be tuned that it can be used in optical devices.

Influence of deposition temperature on structure and morphology of nanostructured SnO 2 films synthesized by pulsed laser deposition

Nanostructured tin oxide thin films were deposited on the Si (100) substrate using the pulsed laser deposition technique at different substrate temperatures (300, 450 and 600 °C) in an oxygen atmosphere. The structure and morphology of the as-deposited films indicate that the film crystallinity and surface topography are influenced by the deposition temperature by changing from an almost amorphous to crystalline microstructure and smoother topography at a higher substrate temperature. The photoluminescence measurement of the SnO 2 films shows three stable emission peaks centered at respective wavelengths of 591, 554 and 560 nm with increasing deposition temperature, contributed by the oxygen vacancies.

Nanostructured Columnar Tin Oxide Thin Film Electrode for Lithium Ion Batteries

Nanostructured tin oxide thin films with columnar grains were deposited on gold-coated silicon substrates using the combustion chemical vapor deposition method. Microscopy revealed that the columnar grains were covered by nanoparticles of less than 20 nm. The electrochemical behavior of the as-prepared thin film electrodes was examined against a lithium counter electrode. These thin film electrodes exhibited high specific capacity and good capacity retention. The capacity increased from an initial value of about 353 (μA h)/(cm2 μm) gradually to a maximum value of ∼490 (μA h)/(cm2 μm) during cycling. The reversible capacity was about 460 (μA h)/(cm2 μm) after 80 cycles at a charge/discharge rate of 0.3 mA/cm2. When the electrodes were discharged at 0.9 mA/cm2, the capacity retention obtained was about 64% of the capacity at 0.3 mA/cm2. The good electrochemical performance is attributed to the unique nanostructure with longitudinal and radial connectivity of active materials.

Microstructure and physical properties of nanostructured tin oxide thin films grown by means of pulsed laser deposition

The pulsed laser deposition (PLD) of tin oxide (SnO 2) thin films onto both alumina and quartz substrates have been achieved by ablating poly-SnO 2 pellets with a KrF excimer laser. At a laser fluence of ∼ 4.6 J/cm 2, the effect of both background pressure (vacuum and 150 mTorr of oxygen) and deposition temperature ( T d ranging from 20 to 600 °C) were investigated. While all the films deposited under 150 mTorr of oxygen consisted of pure polycrystalline SnO 2 phase and were almost stoichiometric ([O]/[Sn] ∼1.9) even for T d as low as 20 °C, those deposited under vacuum were found to be composed of both amorphous SnO and poly-SnO 2 phases. Scanning and transmission electron microscopy observations have revealed that the micro-/nano-structure of the PLD SnO 2 films changes from a relatively porous fine-grained to a completely columnar microstructure as T d is raised from 20 to 600 °C. In particular, the average diameter of the SnO 2 nanograins was found to increase markedly (from 4 to ∼12 nm) when T d is increased from 20 to 450 °C and above. On the other hand, the resistivity (ρ) of the PLD SnO 2 films, deposited under 150 mTorr of oxygen, was found to decrease significantly from 200 to ∼2 Ω cm when T d is increased from 150 to 450 °C. The optical band gap ( E g) of the PLD SnO 2 films increased from ∼2.6 to ∼4.0 eV when the deposition environment is changed from vacuum to 150 mTorr of oxygen while it is slightly affected by the variation of T d. The observed variations of ρ and E g are correlated to nanograin size variation and oxygen vacancies concentration in the films, respectively.