The structure-property relationship of polymer/layered silicate nanocomposites was investigated in this study. Polymer nanocomposites based on completely amorphous poly(hexamethylene isophthalamide) with exfoliated, intercalated, or agglomerated nanoclay morphology were produced and analyzed by X-ray diffraction and transmission electron microscopy. Differential scanning calorimetry measurements were used to characterize the glass-transition behavior. Dynamic mechanical analysis was performed to investigate the nature of the constrained region as the reinforcement mechanism. The modulus enhancement of the organoclay nanocomposites was found to have good linear correlation with the volume of the constrained region. The type of polymer-nanofiller interaction strongly influences the amount and modulus of the constrained region, and both of the latter contribute to the enhancement in the storage modulus of the polymer nanocomposite. The mechanical properties of the constrained region are temperature-dependent. Constrained region models for polymer nanocomposites were proposed on the basis of these results. The constrained volume in amorphous polymer nanocomposites was found to be much less than that in semicrystalline systems.

A novel amorphous polyamide/montmorillonite nanocomposite based on poly(hexamethylene isophthalamide) was successfully prepared by melt intercalation. Wide angle X-ray diffraction and transmission electron microscopy showed that organoclay containing quaternary amine surfactants with phenyl and hydroxyl groups was delaminated in the polymer matrix resulting in well-exfoliated morphologies even at high montmorillonite content. Differential scanning calorimetry results indicated that clay platelets did not induce the formation of a crystalline phase in this amorphous polymer. Tensile tests demonstrated that the addition of nanoclay caused a dramatic increase in Young's modulus (almost twofold) and yield strength of the nanocomposites compared with the homopolymer. The nanocomposites exhibited ductile behavior up to 5 wt % of nanoclay. The improvement in Young's modulus is comparable with semicrystalline aliphatic nylon 6 nanocomposites. Both the main chain amide groups and the amorphous nature of the polyamide are responsible for enhancing the dispersion of the nanofillers, thereby, leading to improved properties of the nanocomposites. The structure-property relationship for these nanocomposites was also explored.

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A self-aligned Ni-InGaAs metallic source and drain ͑S/D͒ technology for In 0.7 Ga 0.3 As channel n-MOSFETs ͑metal-oxidesemiconductor field-effect transistors͒ is reported. A process was developed for selective contact metallization on InGaAs, comprising a reaction of Ni with In x Ga 1−x As to form a metallic Ni-InGaAs material, and a selective removal of excess Ni using a wet etch. Ni-InGaAs has low sheet resistance, is ohmic on n-In x Ga 1−x As, and forms a Schottky contact on p-In x Ga 1−x As. A selfaligned salicidelike integration scheme was used to realize In 0.7 Ga 0.3 As n-MOSFETs with self-aligned Ni-InGaAs metal S/D. n-MOSFETs with a gate length of 1 m shows good transfer characteristics with an on-state/off-state drain current ratio of ϳ10 3 and peak transconductance G m of 74 S/m. III-V materials such as indium gallium arsenide ͑InGaAs͒ have significantly higher electron mobility than silicon ͑Si͒ and have been explored as alternative channel materials in field effect transistors ͑FETs͒ for logic applications. 1-11 One of the challenges for achieving high drain current I DS performance is the realization of low source and drain ͑S/D͒ series resistance R S/D , which includes metalsemiconductor contact resistance. 12-16 Achieving high S/D doping concentration by ion implantation and annealing is difficult for some III-V materials. To realize low R S/D in III-V FETs, selective growth of in situ doped S/D materials 17-19 and self-aligned contacts are needed. 15,16,19,20 Forming metallic S/D is another attractive option. 21,22 The metallic S/D should preferably be self-aligned. However, a nickel-salicidelike process involving direct reaction of a nongold metal with III-V material for the formation of self-aligned metal S/D has not been demonstrated.In this work, we report a new salicidelike self-aligned NiInGaAs metallization technology and its integration in In 0.7 Ga 0.3 As channel n-MOSFETs ͑metal-oxide-semiconductor field effect transistors͒ to form metal source/drain.

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The structural, compositional, and electrical properties of epitaxial Ni4InGaAs2 (denoted as Ni-InGaAs) film formed by annealing sputtered Ni film on InGaAs were investigated. It was found that Ni-InGaAs adopts a NiAs (B8) structure with lattice parameters of a = 0.396 ± 0.002 nm and c = 0.516 ± 0.002 nm, and exhibits an epitaxial relationship with InGaAs, with orientations given by Ni-InGaAs[1¯10]//InGaAs[001] and Ni-InGaAs[110]//InGaAs[110]. The epitaxial Ni4InGaAs2 film has bulk electrical resistivity of ∼102 μΩ·cm, which increases as the film thickness scales below 10 nm. The results of this work would be useful for the development of contact metallization for high mobility InGaAs metal-oxide-semiconductor field-effect transistors.