Thin films spin coating

Interest in the synthesis and processing of mesoporous silica materials has grown extensively since their discovery in 1992, and the exciting potential that these films hold in low-k dielectrics, sensors, nanowire fabrication, catalysis, membrane separations, and many other applications will continue to fuel academic and industrial interest in these films. While there are many new synthesis routes for processing mesoporous silica thin films, spin coating and dip coating remain the most facile methods available. These methods deliver high quality reproducible films that can be used for any of the variety of applications. 

Time-resolved PL measurements were also performed using time-correlated single-photon counting (TCSPC) and photoluminescence upconversion (PLUC) spectroscopies. Descriptions of the setups can be found in refs. [14, 65], respectively. All measurements were taken in continuous-flow He cryostats (Oxford Instruments OptistatCF) under inert conditions. Finally, PL efficiency measurements were performed on simple polymer thin films spin coated on Spectrosil substrates using an integrating sphere coupled to an Oriel InstaSpec IV spectrograph and excitation with the same Ar+ laser as above. 

Fig. 1.13 a Structures of bi-UPy photochromic dithienylethene 45 and mono-UPy-terminated fluorescent dye FI b Depiction of the energy transfer (ET) process of the thin film spin coated from solutions of 97 3 4S-F1 under UVA is irradiation, (green open form of 45 purple closed form of 45 yellow FI) Reproduced from Ref. [112] by permission of John Wiley Sons Ltd... 

Fig. 1.17 CD spectra of PMBET recorded at room temperature from thin films spin-coated onto glass plates after fast (a) and slow (b) cooling from 200°C to 20°C. Adapted from Bou-man et al. [47] with permission from Wiley-VCH.

Huang, X. Pelegri, A. A. Nanoindentation Measurements on Low-k Porous Silica Thin Films Spin Coated on Silicon Substrates. Journal of Engineering Materials and Technology 125, 361-367 (2003). 

Fig. 2.5 Normalized UV-vir absorption spectra of a IID-Se b IID-NDT c IIDDT-Me and d IID-T3 in CHCI3 (1 x 10 M), in thin film (spin-coated from TCE solution, 1 mg/mL), and in annealed film (at 150 °C for 30 min)...

Thin films spin-coated from diluted BMBF solution onto precleaned Si wafer were prepared with different thickness and different 5/molar ratio, as well. The films were stepwise annealed, fast cooled, and examined offline. Figure 11.20 shows the XR-curves obtained on copolymer samples with different sfMA concentration and film thickness. It gives an impression about the influences on the structure formation in thin films, that is, in confined space dimensions. Most important influences are the kind of substrate and surface, preparation, annealing and cooling conditions, as well as the film thickness. 

The electronic absorption spectra of dilute (typically 5-10 mg/1) solutions of poly(9,9-dialkyl-fluorenes) show a sharp peak with Amax 385-390 nm (3.2 eV) of tt-tt electronic transition. Thin solid films (spin coated from 15 to 20mg/ml solutions) reveal similar absorption with a slightly red-shifted ( 10 nm) and relatively broader peak (due to intermolecular interaction) (Figure 2.9) [246],... 

Fig. 2 A schematic for spin coating thin films. The coating solution is either (A) dripped on the substrate while it is at rest or (B) dripped on while the substrate is spinning (C) spin-off stage, forming a thin liquid coating on the substrate (D) solvent evaporation results in self-assembly and thin film formation.

Thin film dielectrics are usually deposited using chemical vapor deposition (CVD). A variation of CVD utilizing a plasma discharge is called plasma-enhanced CVD (PECVD) and is the standard in IC fabrication for the deposition of dielectric films. Plasma-enhanced CVD involves the formation of a solid film in a substrate surface from volatile precursors (vapor or gas) in a plasma discharge. The precursors are chosen to contain the constituent elements of the final film and chemical reactions in the gas phase are encouraged. They are condensed in a substrate that is heated or cooled. It will be shown later that porosity can be introduced in the PECVD films. Spin coating is another preparation technique and a popular choice... 

Figure 21.6 Cls XPS spectra of a P(VDF-TrFE) film, spin-coated onto an Al/Si substrate (bottom electrode structure). Thick solid curve just after spin coating. Dashed curve after thermal armeahng at 135 °C for 2 h. The concentration for spin coating is 0.1 wt% P(VDF-TrFE) in 2-butanone. Spectra are corrected for 0.4 eV and normalised with reference to the bulk film, also shown (thin solid curve).

Tetrathiafulvalene (TTE) has also been used in electrochromic devices. TTE-based polymers spin-coated onto transparent electrode surfaces form stable thin films with reproducible electrochromic properties (100). The slow response of these devices has been attributed to the rate of ion movement through the polymer matrix. 

Solution Deposition of Thin Films. Chemical methods of preparation may also be used for the fabrication of ceramic thin films (qv). MetaHo-organic precursors, notably metal alkoxides (see Alkoxides, metal) and metal carboxylates, are most frequently used for film preparation by sol-gel or metallo-organic decomposition (MOD) solution deposition processes (see Sol-GEL technology). These methods involve dissolution of the precursors in a mutual solvent control of solution characteristics such as viscosity and concentration, film deposition by spin-casting or dip-coating, and heat treatment to remove volatile organic species and induce crystaHhation of the as-deposited amorphous film into the desired stmcture. 

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