For the production of oxide nanoparticles at a commercial scale, flame spray processes are frequently used where mostly oxygen is fed to the flame if high combustion temperatures and thus small primary particle sizes are desired. To improve the understanding of these complex processes in situ, noninvasive optical measurement techniques were applied to characterize the extremely turbulent and unsteady combustion field at those positions where the particles are formed from precursor containing organic solvent droplets. This particle-forming regime was identified by laser-induced breakdown detection. The gas phase temperatures in the surrounding of droplets and particles were measured with O(2)-based pure rotational coherent anti-Stokes Raman scattering (CARS). Pure rotational CARS measurements benefit from a polarization filtering technique that is essential in particle and droplet environments for acquiring CARS spectra suitable for temperature fitting. Due to different signal disturbing processes only the minority of the collected signals could be used for temperature evaluation. The selection of these suitable signals is one of the major problems to be solved for a reliable evaluation process. Applying these filtering and signal selection steps temperature measurements have successfully been conducted. Time-resolved, single-pulse measurements exhibit temperatures between near-room and combustion temperatures due to the strongly fluctuating and flickering behavior of the particle-generating flame. The mean flame temperatures determined from the single-pulse data are decreasing with increasing particle concentrations. They indicate the dissipation of large amounts of energy from the surrounding gas phase in the presence of particles.
Photoinduced electron transfer processes in dye-semiconductor systems with different spacer groups J. Chem. Phys. 137, 22A529 (2012) Raman scattering and anti-Stokes luminescence in poly-paraphenylene vinylene/carbon nanotubes composites J. Appl. Phys. 111, 083109 (2012) Ni filled flexible multi-walled carbon nanotube-polystyrene composite films as efficient microwave absorbers Appl. Phys. Lett. 99, 113116 (2011) Organic bistable memory based on Au nanoparticle/ZnO nanorods composite embedded in poly (vinylpyrrolidone) layer Appl. Phys. Lett. 99, 023303 (2011) Organic bistable memory based on Au nanoparticle/ZnO nanorods composite embedded in poly (vinylpyrrolidone) layer APL: Org. Electron. Photonics 4, 132 (2011) Additional information on J. Appl. Phys.
Indium–zinc
oxide (IZO) films were deposited via flame spray pyrolysis (FSP) by
pulsewise shooting a Si/SiO2 substrate directly into the
combustion area of the flame. Based on UV–vis measurements
of thin-films deposited on glass substrates, the optimal deposition
parameters with respect to low haze values and film thicknesses of
around 100 nm were determined. Thermal annealing of the deposited
films at temperatures between 300 and 700 °C was carried out
and staggered bottom gate thin-film transistors (TFT) were fabricated.
The thin films were investigated by scanning electron microscopy,
atomic force microscopy, X-ray diffraction, Fourier transformed infrared
spectroscopy, and room-temperature photoluminescence measurements.
The outcome of these investigations lead to two major requirements
in order to implement a working TFT: (i) organic residues from the
deposition process need to be removed and (ii) the net free charge
carrier concentration has to be minimized by controlling the trap
states in the semiconductor. The optimal annealing temperature was
300 °C as both requirements are fulfilled best in this case.
This leads to field effect transistors with a low hysteresis, a saturation
mobility of μSat = 0.1 cm2/(V s), a threshold
voltage of V
th = −18.9 V, and an I
on/I
off ratio on
the order of 107. Depending on thermal treatment, the defect
density changes significantly strongly influencing the transfer characteristics
of the device.
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