No abstract

In this study, we investigate the growth and internal properties of polyelectrolyte multilayer films made of poly(l-lysine) and hyaluronan (PLL/HA) under pH-amplified conditions, that is, by alternate deposition of PLL at high pH and HA at low pH. We focus especially on the influence of the molecular weight of HA in this process as well as on its concentration in solution. Film growth was followed by quartz crystal microbalance and by infrared spectroscopy to quantify the deposited mass and to characterize the internal properties of the films, including the presence of hydrogen bonds and the ionization degree of HA in the films. Film growth was significantly faster for HA of high molecular weight (1300 kDa) as compared with 400 and 200 kDa. PLL was found to exhibit a random structure once deposited in the films. Furthermore, we found that PLL-ending films are more stable when they are placed in PBS than their HA counterparts. This was explained on the basis of more cohesive interactions in the films for PLL-ending films. Finally, we quantified PLL(FITC) diffusion into the films and observed that PLL diffusion is enhanced when PLL is paired with the HA of high MW. All together, these results suggest that besides purely physicochemical parameters such as variation in pH, the molecular weight of HA, its concentration in solution, and the possibility to form intermolecular HA association play important roles in film growth, internal cohesion, and stability.

Abstract. Chemical deposition methods like MOD and MOCVD are promising approaches for coated conductors (CCs) due to their reduced cost and easy scaling.High quality La2Zr2O7 (LZO) buffer layers were prepared by MOD on Ni-5%at.W (NiW) RABiTS and subsequent YBCO layers (450 to 800 nm thick) were deposited by pulsed injection MOCVD, leading to a simple low cost architecture NiWRABiTS/LZOMOD/YBCOMOCVD. In this novel combination of MOD and MOCVD approach, a single LZOMOD buffer layer is sufficient to ensure structural compatibility between YBCO and NiW, and protect the substrate from oxidation during YBCO MOCVD. YBCO films were epitaxially grown on LZO and exhibited critical current densities Jc close to 1 MA/cm2 at 77 K with a critical temperature Tc = 91 K and ∆Tc < 1 K.

No abstract

Thin films of HfO 2 were deposited on (100)Si/SiO 2 by liquid-injection metal-organic (MO)CVD using [Hf(O t Bu) 2 (mmp) 2 ] dissolved in octane as the precursor. A precise thickness control on the nanometer scale was obtained by controlling the volume of injected precursor solution. Films of thickness below 10 nm were studied by means of X-ray reflectometry (XRR), attenuated total reflection infrared spectroscopy (ATR), and atomic force microscopy (AFM). Films are amorphous for deposition temperatures below 350°C; they are polycrystalline at deposition temperature of 360°C and above, except for ultrathin films. Under the deposition conditions used, the main crystalline phase is the monoclinic phase as shown by ATR. AFM reveals smooth surfaces for both amorphous and polycrystalline films. The equivalent oxide thickness measured in MOS structures depends linearly on the film's thickness, and a relative dielectric permittivity e r of 19 is obtained, which is consistent with that expected for the monoclinic phase of bulk HfO 2 . Leakage current densities of the order of 1×10 -4 A cm -2 for films with a physical thickness of 3.1 nm are obtained. Rapid thermal annealing under ammonia reduces the fixed charges in the oxide (Q ox < 1×10 11 cm -2 ) as well as the interfacial charge density (D it peak = 8×10 10 eV -1 cm -2).

No abstract

No abstract

No abstract