## 3 Fluorine Materials and Polymers
This resulted in significant improvement of the effective channel mobility (\(\upmu_{\text{eff}}\)), transconductance (G\({}_{\text{m}}\)), drive current (Id), and sub-threshold swing (SS). With F incorporation, they have successfully developed excellent interface quality of HfO\({}_{2}\) directly on In0\({}_{.53}\)Ga0\({}_{.47}\)As without using interface passivation layer. Fluorinated samples exhibit low interface trap density (Dit) of 4.9 \(\times\) 10\({}^{11}\) cm\({}^{-2}\)eV\({}^{-1}\), which is the lowest value compared to prior reported HfO\({}_{2}\)/In0\({}_{.53}\)Ga0\({}_{.47}\)As gate stacks. Incidentally, [PERSON] and coworkers [9] have reported a simple technique to synthesize highly crystalline InGaAs NWs by a novel two-step chemical vapor deposition (CVD) method with a high growth yield. The NWs exhibit impressive electrical performance with a I\({}_{\text{ON}}\)/I\({}_{\text{OFF}}\) ratio of \(\sim\)10\({}^{5}\) and field-effect mobility of \(\sim\)2,700 cm\({}^{2}\)/(V\(\cdot\)s) when configured in the back-gate NW field-effect transistors (FETs). [PERSON] and [PERSON] [10] in their article _Enhancement of Brillouin Scattering Signal in Perfluorinated Graded-Index Polymer Optical Fibers_ studied two methods to enhance the Brillouin Stokes signal in perfluorinated graded-index polymer optical fibers [PFGI-POFs]. The backscattered Brillouin light spectrum properties of [PFGI-POFs] with 62.5-\(\upmu\)m core diameter were investigated. The Stokes power was extremely high compared to that of a PFGI-POF with 120-\(\upmu\)m core, and the Brillouin threshold power for 5-m PFGI-POF was estimated to be 53.3 W. It was also shown that employing a PFGI-POF longer than \(\sim\)50 m is not an effective way to enhance the Stokes signal. In addition, it was theoretically found that it is difficult to reduce the Brillouin threshold power of PFGI-POFs at 1.55-\(\upmu\)m wavelength below that of long silica single-mode fibers even if their core diameter is sufficiently decreased to satisfy the single-mode condition. Finally, the Brillouin linewidth narrowing effect was confirmed. The authors conclude that these results will be a good guideline for developing practical Brillouin systems using PFGI-POFs, as well as for designing new PFGI-POF structures for Brillouin applications in future. As urea and amide derivatives are ideal functional groups for the design of low molecular weight gelators, attributed to their rigidity, strength and ability to form highly directional hydrogen bonds, [PERSON] and [PERSON] [11] in their article _Self-Assembled Fluorinated Organogelators for Surface Modification_ prepared some novel alkyl- and perfluoroalkyl-containing urea and amides from amino acid derivatives and investigated their utilization as low molecular weight organogelators. Most of these compounds showed excellent gelation behavior in organic solvents at low concentrations. A few organogelators selected from the initial screening were used for surface modification of fibrous substrates to create hydrophobic and oleophobic composites. The hydrophobic and oleophobic behaviors of these composites were ascribed to a combination of increased surface roughness and the alkyl/fluorinated functionalities present in the gelator backbone. In general the urea-amide derivatives were better gelators than the corresponding bis- or tris-amide derivatives. Analogous urea-ester derivatives failed to gel in any organic solvents, indicating a combination of urea and amide functionalities, or multiple amide groups, are desirable to induce gelation. The nonwoven surfaces impregnated with perfluoroalkyl-containing organogelators showed excellent oleophobic behavior. Superior hydrophobic and oleophobic behavior exhibited by these composites were attributed to a combination of micro-structured surface morphology created by the xerogel and the presence of fluorocarbon/hydrocarbon functionalities in the gelator backbone.