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Abstract: An effective dedoping method for organic semiconductors using tetrakisdimethylaminoethylene (TDAE) was demonstrated using poly(3-hexylthiophene) thin film transistors in top gate configuration. Devices were treated after production and showed improved on/off ratios of up to 105 with little change in the field effect mobility. [Copyright &y& Elsevier]

The microstructure of pulsed-laser-deposited SrRuO[sub 3] films on Si(001) with SrO buffer layers has been studied by means of high-resolution electron microscopy and energy-dispersive X-ray spectroscopy. It was found that good epitaxial growths of the SrO buffer layers and the subsequent SrRuO[sub 3] films were achieved on the Si(001) substrates. Multiple domains were formed in the SrRuO[sub 3] films with domain boundaries nearly perpendicular to the interface between the SrRuO[sub 3] films and the SrO buffer layers. A high density of planar defects, such as twins, stacking faults and antiphase boundaries, were formed along the (022) lattice plane of the SrRuO[sub 3] films. Lattice strains in the constituting layers were investigated by means of fast Fourier transformation of local regions in the highresolution images. It was found that, close to the interface between the SrRuO[sub 3] films and the SrO buffer layers, both the layers were elastically strained in the opposite sense. The structure of coherent twin boundary in the SrRuO[sub 3] films was determined using a computer-aided high-resolution image simulation method. The comparison between the simulated and the experimental images indicated that the Sr-O plane constituted the twin boundary. [ABSTRACT FROM AUTHOR]

In this letter the authors describe the fabrication of high performance polymer thin film transistors using an aqueous based silver colloid to form source and drain electrodes patterned by brush painting. The electrode dimensions were controlled by a surface energy pattern defined by soft contact printing of a self-assembled monolayer 1H,1H,2H,2H-perfluorodecyl-trichlorosilane on a SiO2 surface which acted as a dewetting layer for the painted silver particle suspension. Another self-assembled monolayer of 1H,1H,2H,2H-perfluorodecanethiol was also used to increase the work function of the patterned silver electrodes in order to decrease the barrier for charge injection into the polymer semiconductor. The field-effect mobility of the thin film transistors fabricated by this method approached 0.02 cm2 V-1 s-1 with an on/off current ratio of 105. The relative high mobility may be influenced by the ordering of the poly(3-hexylthiophene) semiconductor layer by the self-assembled monolayer used to define the source and drain electrodes. [ABSTRACT FROM AUTHOR]

A method to fabricate polymer field-effect transistors with submicron channel lengths is described. A thin polymer film is spin coated on a prepatterned resist with a low resolution to create a thickness contrast in the overcoated polymer layer. After plasma and solvent etching, a submicron-sized line structure, which templates the contour of the prepattern, is obtained. A further lift-off process is applied to define source-drain electrodes of transistors. With a combination of ink-jet printing, transistors with channel length down to 400 nm have been fabricated by this method. We show that drive current density increases as expected, while the on/off current ratio 106 is achieved. [ABSTRACT FROM AUTHOR]

We show that there exists a nondispersive (or elastic) capacitance component Cnon which is independent of frequency f, ac amplitude VOSC, and dc bias voltage Vdc, in the frequency range of 0.063 Hz–1 MHz. It can be separated from the total capacitance Ct of ferroelectric thin films by using either the C(Vdc,f)-C[Vdc,f(r)](VOSC=const) or C(f,VOSC)-C[f,VOSC(r)](Vdc=const) plot, where f(r) and VOSC(r) are the referenced frequency and ac amplitude, respectively. Our results suggest that the dispersive and nondispersive capacitance components may originate from different dielectric relaxation mechanisms. The extracted nondispersive Cnon can be a useful physical parameter in evaluating maximum dielectric tunability for the phase-shift application of ferroelectric thin films in microwave devices and characterizing phase-transition temperature in a multilayered 0.2Pb(Zn1/3Nb2/3)O3–0.8BaTiO3/Pb(Mg1/3Nb2/3)O3 relaxor. [ABSTRACT FROM AUTHOR]

The transient drain current of the single-grain silicon thin-film transistor with gate oxide deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition has been measured by applying a square signal on the gate and a constant low voltage between source and drain. Switch-on undershoot current has been observed, which can be attributed to the motion of space charge in gate oxide. Assuming there are some mobile ions in the gate oxide, we find the drift kinetics of the ions is quite similar to the mobile protons in SiO2, as reported in the literature. [ABSTRACT FROM AUTHOR]

Frequency dependence of the dielectric properties of La-doped lead zirconate titanate thin films with Pt and Ir electrodes and two different La doping levels is studied by impedance spectrometry between 10[sup -3] and 10[sup 4] Hz. A constant phase element with an impedance of Z=A[sub 0](jω)[sup -α] is introduced into the equivalent circuit, which fits very well both the real and imaginary components of the measured impedance over the full frequency range, including the resonance, using a single α (0«α<1). Our analysis shows that α is not related to the ferroelectric properties of the films, but it has a monotonic correlation with the real dielectric constant. The close resemblance to the well-known butterfly-shaped C–V curve shown by α with the applied dc bias (α-V) suggests that α may be affected by the density of the domain walls in the film, in addition to various dielectric relaxation processes. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The effect of substrate temperatures on the structure of self-assembled monolayers (SAs) of organosilane (CH 3 )(CH 2 ) 17 Si(OC 2 H 5 ) 3 on SiO 2 substrates were investigated by X-ray reflectometry and water contact angle measurements. (CH 3 )(CH 2 ) 17 Si(OC 2 H 5 ) 3 SAMs were fabricated by a chemical vapor deposition process for two hours, and the substrate temperature was varied between 80 and 170°C. The angular dependence of the specular X-ray reflectivity was measured, and thickness, density, surface roughness and interface roughness of SAMs were determined by fitting the observed curves to model calculations. It was clarified that the thickness, density and water contact angles of SAMs increased lineally with increasing temperature, and saturated at temperatures higher than 140°C. [ABSTRACT FROM AUTHOR]

The ohmic conductivity of the sol–gel derived Pb[sub 1+y](Zr[sub 0.3]Ti[sub 0.7])O[sub 3] thin films (with the excess lead y=0.0 to 0.4) are investigated using low frequency small signal ac and dc methods. Its temperature dependence shows two activation energies of 0.26 and 0.12 eV depending on temperature range and excess Pb levels. The former is associated with Pb[sup 3+] acceptor centers, while the latter could be due to a different defect level yet to be identified. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report upon the measurement and simulation of the switch-on transient of polycrystalline silicon (poly-Si) thin-film transistors. The measurement of the switch-on transient reveals an unexpectedly long transient that cannot be explained by the theory adopted for single-crystal silicon-on-insulator (SOI) devices. Contrary to the SOI case, the transient is seen to increase with source-drain voltage. In order to explain the experimental findings, we have performed simulations of the transient and found that the results are heavily dependent upon the density of states in the band gap and their capture cross sections. Only when energy-dependent cross sections are adopted do the calculations correctly reproduce the steady-state and overshoot currents, and also the transient duration. A physical interpretation of this phenomenon is presented. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]