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Low Substrate Temperature (low + substrate_temperature)
Selected AbstractsPreparation of undoped and indium doped ZnO thin films by pulsed laser deposition methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2005B. Kotlyarchuk Abstract An original modification of the standard Pulse Laser Deposition (PLD) method for preparing both undoped and indium doped zinc oxide (ZnO:In) thin films at low substrate temperature is proposed. This preparation method does not demand any further post-deposition annealing treatment of the grown films. The developed method allows to grow thin films at low substrate temperature that prevents them from the considerable loss of their intrinsic electrical and optical properties. The influence of deposition parameters on the electrical and optical parameters of the undoped and the indium doped ZnO thin films is also analysed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Role of polymers in CVD growth of nanocrystalline diamond films on foreign substratesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009A. Kromka Abstract Spin coating of PVA polymer with fine grained diamond powder is used as the nucleation treatment for achieving growth of nanocrystalline diamond (NCD) thin films. The growth is realized by standard microwave plasma chemical vapor deposition (CVD). The morphology and character of deposited NCD film is strongly related to the growth temperature. The low temperature process (430°C) results in a growth of well-faceted continuous films. The high temperature process (830,°C) results in voids and openings in the layer. Addition of PVA as the interlayer between the substrate and the seeding polymer composite leads to more openings. The effect is the most pronounced at 830,°C. This is assigned to thermal instability of PVA and oxygen chemistry present in the early beginning of the CVD growth. An optimized seeding process based on the polymer composite procedure at low substrate temperature and low PVA amount allows the diamond growth on extremely soft substrates. [source] Study on the excimer laser annealed amorphous hydrogenated silicon carbon films deposited by PECVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010G. Ambrosone Abstract Hydrogenated amorphous silicon carbon films of different carbon content were deposited by plasma enhanced chemical vapour deposition at low substrate temperature (200 °C) and were subjected to excimer laser annealing. X-ray diffraction spectra and field emission scanning electron microscopy images demonstrate that carbon content plays an important role in facilitating the crystallization process induced by the excimer laser treatment (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Production of B4C coatings by CVD method in a dual impinging-jet reactor: Chemical yield, morphology, and hardness analysisAICHE JOURNAL, Issue 11 2009Mustafa Karaman Abstract ,-rhombohedral boron carbide (B4C) was deposited on a tungsten substrate from a BCl3H2CH4 gas mixture in a dual impinging-jet chemical vapor deposition reactor. On-line FTIR analysis of the product stream proved the formation of BHCl2 and HCl as by products, in a competing parallel reaction. A maximum of 13% chemical yield of boron carbide was observed, and the yield was found to have increasing trend with an increase in temperature. XRD analysis proved the existence of rhombohedral B4C phase at 1300°C without any other B4C phases or impurities. At this temperature, the formation of 5-fold icosahedral boron carbide crystals up to 30 micron sizes was observed. Such highly symmetric crystalline regions were observed to have a very high hardness value of 4750 kg/mm2 as revealed from the microhardness analysis. The change in product morphology at low substrate temperatures resulted in a decrease in the hardness values. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Challenges of introducing quantitative elementary reactions in multiscale models of thin film depositionPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2010Alessandro Barbato Abstract The implementation of detailed surface kinetic mechanisms describing the thin film growth dynamics into models of chemical vapor deposition (CVD) reactors has been a challenge for many years. In this article we review the literature concerning the study of the dynamics of the Si(100)2,×,1 surface and introduce a multiscale model that captures the main features of its reactivity. The model combines the results of ab initio calculations with an atomistic description of the Si surface, obtained using a 3D-kinetic Monte Carlo (KMC) model that explicitly accounts for the 2,×,1 surface reconstruction and the formation and diffusion of Si dimers on a hydrogenated surface. At the atomistic scale, we determined pre-exponential factors and activation energies of hydrogen desorption reactions proceeding through the 2H, 3H, and 4H mechanisms. The calculated kinetic constants were embedded in the KMC model and used to simulate literature TPD experimental data. The simulations were used to fit the activation energies of hydrogen desorption reactions, which showed that DFT calculations performed with B3LYP functionals are likely to overestimate hydrogen desorption energies by up to 9,kcal,mol,1, which was confirmed by successive ab initio calculations. Two examples of the solution of the KMC model in conjunction with a reactor scale model are provided, in which the coupling was performed adopting both a hierarchic and a two-way coupling strategy. We found that in the plasma deposition of nanocrystalline silicon performed at low substrate temperatures the growth proceeds through a layer-by-layer mechanism on a surface almost completely covered by hydrogen. The application of the same model to the simulation of the thermal CVD of Si showed that at intermediate growth temperatures, when the hydrogen surface concentration is high, a new hydrogen desorption mechanism, in which Si adatoms play an important role, is active. Length scales encountered in multiscale modeling of thin films deposition. [source] Low-temperature MBE-grown GaBiAs layers for terahertz optoelectronic applicationsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2009Vaidas Pa, ebutas Abstract Gallium bismide arsenide epitaxial layers were grown by molecular-beam-epitaxy at low substrate temperatures and investigated for their suitability in terahertz optoelectronic applications. Optical pump-terahertz probe measurements on these layers have shown that carrier dynamics can be described using two characteristic times. The faster decay component has characteristic times shorter than 1 ps, whereas the slower component decays in several tens of picoseconds. Fitting the electron lifetimes dependence on optical excitation level the electron trapping cross-section and trap density were determined. The possible mechanism of carrier recombination was discussed. The photoconductive terahertz emitters and detectors made from GaBiAs layers have been manufactured and used in time-domain spectroscopy system with a signal bandwidth larger than 4.5 THz. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||