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A sensing layer for a chemically sensitive field-effect transistor (CHEMFET) based on a composite of camphorsulfonic acid (CSA)-doped polyaniline (PANI) and the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethanesuffonyl)-imide, BMI([Tf.sub.2]N), has been developed and characterized for the sensing of ammonia gas. The work function responses of the cast films with and without IL were analyzed by 'stepwise' changes of ammonia gas concentration from 0.5 to 694 ppm in air as a function of the mole fraction of IL to PANI. The PANI. CSA/BMI([Tf.sub.2]N) layers showed enhanced sensitivities, lower detection limits, and shorter response times. There is experimental evidence that PANI forms a charge-transfer complex with imidazolium cation.

Two-dimensional simulations of an ambipolar organic heterostructure field-effect transistor (FET) with a bottom Au contact and an Mg top contact are presented. The simulated current-voltage characteristics of the heterostructure have featured all specific characteristics arising from the ambipolar operation in the case of more realistic material parameters.

The role of interface chemistry on the effective work function and device characteristics of metal gate electrodes on hafnium dioxide (Hf[O.sub.2]) gate dielectrics in metal oxide semiconductor field effect transistors is examined. The results have shown that the effective work function and device threshold voltage are reduced when the less electronegative carbon atom is substituted for the more electronegative nitrogen atom.

Direct oxidation by an ultraviolet (UV) and ozone process and oxinitridation (plasma nitridation after oxidation) GaAs surfaces were used to form nanometer-scale gate insulating layers for depletion-type recessed gate GaAs-MISFETS. The oxinitrided gate device (GaAs-MISFET) exhibited smaller leakage current than the simple oxide gate device.

Fabrication and characterization of the crystalline self-assembled monolayers (SAMs) of organosilane compounds such as octadecyltrimethoxysilane (OTMS) and octadecyltrichlorosilane (OTCS) deposited by a simple, spin-casting technique onto Si/Si[O.sub.2] substrates is demonstrated. The characterization showed the monolayers to exhibit a well-packed crystalline phase and a remarkably high degree of smoothness.

A series of novel electroactive and photoactive conjugated copolymers based on N-alkyl dithioeno[3,2-b:2',3'-d]pyrroles (DTP) and thiophene (TH) units (DTP-co-THs) are prepared by using a Stille coupling reaction. The results have shown that the presence of highly ordered microcrystalline structures in thin films of organic semiconductors is not necessary for excellent performance of organic transistors.

A new model is described for calculating Coulomb perturbation potentials in bidimensional semiconductor structures. The results have shown that lower Coulomb perturbation potentials are expected due to the charges if the interfacial layer is eliminated or reduced.

Organic thin film field-effect transistors (OTFTs) with mobility up to 1.0 [cm.sup.2] [V.sup.-1] [s.sup.-1] and on/off ratio of [10.sup.6]-[10.sup.8] as well as good environmental stability are shown by using vanadyl phthalocyanine (VOPc), a pyramid-like compound with an ultra closely [pi]-stacked structure. The results have shown that the oxygen doping has exerted essential effect on the field-effect property of VOPc, which is distinct from that seen for pentacene-based PFETs.

The detection of glucose based on a liquid-ion gated field-effect transistor configuration is described, where the enzyme-functionalized polypyrrole nanotubes are used as the conductive channel. The enzymatic reaction product, hydrogen peroxide, has played a major role in modulating the charge transport of carboxylated polypyrrole nanotubes.

The first field-effect transistor (FET) device with thin films of old polycyclic aromatic hydrocarbon, picene, is described. The FET properties are improved under air/[O.sub.2] conditions, indicating that the picene FET is an air (or [O.sub.2])-assisted device.

The synthesis and characterization of new electron-depleted N-alkyl-2,2'-bithiophene-3,3'-dicarboximide-based [pi]-conjugated homopolymers and copolymers containing the 2,2'-bithiophene unit are described. The excellent figures of merit of the new class of polymeric semiconductors have disclosed the efficacy of this novel and computationally aided materials design strategy.

A new family of air-stable sulfur-hetero oligoarenes based on the benzo[k]fluoranthene unit is developed as the active materials for thin organic field-effect transistors. The performance of thin film transistors is improved by using the thermal annealing developed by the group, which has provided a new possibility for fabricating organic field-effect transistor (OFET) devices.

A comprehensive set of two-dimensional (2D) inversion layer piezoelectric coefficients is measured by using four-point and concentric-ring wafer bending setups on the (001) and (110) surface and n- and p-type silicon (Si) metal-oxide-semiconductor field-effect transistors (MOSFETs). The studies have shown that for the (001) p-MOSFETs, the longitudinal uniaxial stress has the highest [pi]-coefficient that has little dependence on transverse electric field and is hence most advantageous stress for p-MOSFETs.

The article discusses the ultrathin gate oxide integrity as observed in the Si-channel metal oxide silicon effect transistors (MOSFETs), which are grown on thin virtual substrates. The stress-induced leakage current and oxide reliability are shown to be highly improved by the strain-induced leakage reductions.

The affect of the bias stress effect on the stability of ChemFETs is examined. Results conclude that by utilizing the pulsed gate techniques, the organic thin-film transistor chemical sensors can be used as low drift sensing elements in e-noses.

The synthesis of new hydroxy-terminated, semiconductor-based organic field-effect transistors (OFETs) for phosphonate vapor detection is being described. OFETs are shown to exhibit higher sensitivity and enhanced performance because of its improved chemical properties.

The self-assembly process and the correlation with device performance are studied through ZnO nanorods. It is seen that uniform ZnO nanorod films with defined nanorod alignment can be solution-deposited over large areas by controlling the surface energy of the nanorods through the choice of suitable ligands and by the fluid flow direction during growth.

The observation of 1/f noise in carbon nanotube field-effect transistors is reported as a function of gate potential. The measurements are conducted out in conducting liquid in order to avoid additional low frequency noise contribution from SiO2-nanotube interactions and the results have concluded that the number of carrier fluctuations is the source of the 1/f noise.

The dopant density and the bulk charge-carrier mobility by using concentric device geometry can simultaneously be estimated from the transfer characteristics of a single disordered organic transistor is demonstrated. Doping due to air exposure takes place already in the dark, demonstrating that photoinduced oxygen doping is not the complete picture is observed.