Ozone etching

Fig. 17 SEM image of a high molecular weight ozone-etched PS-PI sample that adopted the gyroid morphology. Reproduced from [69]...

Scheme 3.16 Generation of nanotextured Ag film (AFM height image, top right) from sputtering on UV-ozone etched PS-APIP MS film (AFM height image, top left). Surface-enhanced Raman spectra (SERS) (bottom) of benzenethiol on nanotextured Ag films (10 and 15 nm and respectively) and...

Figure 2.12 Preparation of free-standing platinum nanowires, (a) Cross-sectionai view of a piatinum-filled template. The copolymer template was annealed at 180°C for 35 h with an applied field of 130 V pm". [b] Free-standing platinum nanowires after UV-ozone etching of supporting PFS template. There is partial buckling of individual wires and some degree of aggregation of neighboring wires after removal of the support. Viewing angle is 45°.

Example of template filling by monitoring electrochemical current, (a] Anodic current density in a 780 nm template. The current increases by a factor of 1.8 on filling of the polymer template (accounting for the steady fall in current with a single exponential decay fit), (b) Cross section of templated array after removal of PFS matrix by UV-ozone etching shows the uniform layer of overgrowth over the template surfece. 

The cleaning protocol may include polishing, ultrasonic treatment in different solvents and solutions, plasma and UV/ozone etching, or sputtering a fresh surface from the IRE material, depending on the system under study. The surface cleanliness may be checked by comparing the ATR spectrum of the cleaned sample IRE with the spectrum of a new reference IRE. 

The low temperature nonelectrolytic nickel plating onto three types of polypropylene is carried out by substrate pretreatment with ozone. The latter modifies the polymer surface for galvanization while the combination of polar with anchor effect as a result of the ozone etching enhances the adhesive properties of the polymer surface. The washing of the material after ozonolysis is obligatory for ensuring a good adhesion of the material [117]. 

An ozone treatment (10 minutes at room temperature) of the HF-etched SiC surface before the metallization step was introduced as a very convenient processing step to produce Schottky diode gas sensors with an increased stability and reproducibility. The use of spectroscopic ellipsometry analysis and also photoelectron spectroscopy using synchrotron radiation showed that an oxide, 1-nm in thickness, was formed by the ozone exposure [74, 75]. The oxide was also found to be close to stochiometric SiO in composition. This thin oxide increased the stability of the SiC Schottky diodes considerably, without the need for any further interfacial layer such as Ta or TaSi which have been frequently used. Schottky diodes employing a porous Pt gate electrode and the ozone-produced interfacial layer have been successfully operated in both diesel exhausts and flue gases [76, 77]. 

The SiC Schottky diodes and capacitors that have been processed by the authors were processed on either 6H or 4H substrates (n-type, about 1 x 10 cm ) with a 5-10- m n-type epilayer (2-6 x lO cm" ) [123, 124]. A thermal oxide was grown and holes were etched for the metal contacts. In the case of the Schottky sensors, the SiC surface was exposed to ozone for 10 minutes before deposition of the contact metal. This ozone treatment produces a native silicon dioxide of 10 1 A, as measured by ellipsometry [74, 75]. The MISiC-FET sensors (Figure 2.9) were processed on 4H-SiC, as previously described [125]. The catalytic metal contacts consisted of 10-nm TaSiyiOO-nm Pt, porous Pt, or porous Ir deposited by sputtering or by e-gun. 

Only recently first reports appeared describing the potential of the nanostructured thin block copolymer films for lithographic etching. A thin film of polystyrene-block-polybutadiene with a hexagonal cylindrical morphology where the poly-(butadiene) cylinders were oriented perpendicular to the substrate was deposited on a silicon wafer and selectively decomposed by treatment with ozone or converted with osmium tetroxide. By a subsequent reactive ion etching process the pattern could be inscribed into the surface of the silicon wafer yielding small holes or islands with a lattice constant of 27 nm and hole/island sizes of 13 nm [305,312]. 

Other Methods Examples for other methods include co-casting of a hydrophobic and a hydrophilic polymer that contains amine, imine, hydroxyl, or carboxyl groups [61,89] surface modification by oxidation with ozone or by exposure to an electron or ion-beam ultrasonic etching and UV or laser irradiation [90-92]. A variety of functional groups have been also introduced onto the membrane surfaces by applying the gas discharge techniques (plasma treatment) operated at low or ambient pressure [93,94]. 

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